VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW → Haltech Nexus S3 HT-213000 (auto)
VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW — Haltech — Nexus S3
Drawn by Michael Gnankou · Rev 0 · proposal · 2026-10-23
Before you start
Not confident with automotive wiring? Have a professional harness builder or tuner do it, or check your work before first power-up. A wiring mistake can damage the ECU, the engine or the car, or start a fire.
| Status | proposal · not yet verified: nobody has reported building and running this harness |
|---|---|
| Open errors | none |
| Size of the job | 74 wires · 10 connectors · 0 part lines |
| Tools | Crimp and extraction tools for each terminal family (see Connectors) · wire strippers · multimeter · heat gun + heat-shrink |
| Order of work | 1. Check every part against the parts list. 2. Cut and label every wire (labels: Export → Wire labels). 3. Crimp and pin connector by connector, ticking the build checklist. 4. Run the bench test with nothing plugged in and the battery disconnected. 5. Only then connect the ECU and power up. |
Build checklist
Tick each box as you go. Continuity: meter from end to end, expect under 1 Ω.
| Wire | From | To | Gauge | Colour | Cut | Label | Crimp A | Crimp B | Pin A | Pin B | Continuity |
|---|---|---|---|---|---|---|---|---|---|---|---|
| W1 | OEM-T121-121 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-T121-21 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-T121-3 | MAIN-R-COIL+ | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | NEW-BATT-1 | MAIN-R-IN | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | MAIN-R-COIL- | SP-GND-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | MAIN-R-OUT | NEXUSS3-A-18 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | MAIN-R-OUT | NEXUSS3-A-25 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-T121-1 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-T121-2 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-T121-108 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-T121-29 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-T121-34 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-T121-36 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-T121-90 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-T121-91 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-T121-72 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-T121-73 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-T121-83 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-T121-98 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-T121-99 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | SP-5V1-1 | NEXUSS3-C-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-T121-82 | NEXUSS3-C-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-T121-86 | NEXUSS3-C-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-T121-106 | NEXUSS3-C-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-T121-107 | NEXUSS3-C-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-T121-102 | NEXUSS3-A-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-T121-95 | NEXUSS3-A-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-T121-103 | NEXUSS3-A-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-T121-94 | NEXUSS3-A-30 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-T121-96 | NEXUSS3-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-T121-89 | NEXUSS3-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-T121-97 | NEXUSS3-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-T121-88 | NEXUSS3-A-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-T121-118 | NEXUSS3-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-T121-117 | NEXUSS3-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-T121-53 | NEXUSS3-C-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-T121-101 | NEXUSS3-C-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-T121-33 | NEXUSS3-C-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W44 | OEM-T121-84 | NEXUSS3-C-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W45 | OEM-T121-35 | NEXUSS3-C-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W46 | OEM-T121-92 | NEXUSS3-C-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W47 | OEM-T121-93 | NEXUSS3-C-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W48 | OEM-T121-65 | NEXUSS3-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W49 | OEM-T121-66 | NEXUSS3-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W50 | OEM-T121-5 | NEXUSS3-C-33 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W51 | OEM-T121-63 | NEXUSS3-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W52 | OEM-T121-25 | NEXUSS3-A-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W53 | OEM-T121-80 | NEXUSS3-A-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W54 | OEM-T121-104 | NEXUSS3-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W55 | OEM-T121-105 | NEXUSS3-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W56 | OEM-T121-115 | NEXUSS3-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W57 | OEM-T121-22 | NEXUSS3-A-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W58 | OEM-T121-47 | NEXUSS3-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W59 | OEM-T121-48 | NEXUSS3-A-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W60 | OEM-T121-51 | NEXUSS3-C-31 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W61 | OEM-T121-70 | NEXUSS3-C-32 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W62 | OEM-T121-68 | NEXUSS3-C-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W63 | OEM-T121-69 | NEXUSS3-C-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W64 | OEM-T121-85 | NEXUSS3-C-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W65 | OEM-T121-54 | NEXUSS3-C-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W66 | OEM-T121-28 | NEXUSS3-C-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W67 | OEM-T121-38 | NEXUSS3-C-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W68 | OEM-T121-39 | NEXUSS3-C-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W69 | OEM-T121-40 | NEXUSS3-C-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W70 | OEM-T121-41 | NEXUSS3-C-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W71 | OEM-T121-49 | NEXUSS3-C-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W72 | OEM-T121-60 | NEXUSS3-A-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W73 | OEM-T121-58 | NEXUSS3-A-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W74 | NEW-KEYON-1 | NEXUSS3-A-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ |
Bench test (before first power-up)
Battery disconnected, ECU and every sensor unplugged. Meter on resistance. Each pair below must read open (OL): a reading means a pinched wire, a stray strand or a mis-pinned cavity. Then check continuity of every wire (last column of the build checklist).
| # | Probe A | Probe B | Expect | Why | Reading |
|---|---|---|---|---|---|
| 1 | MAIN-R-COIL+ | NEXUSS3-C-25 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 2 | MAIN-R-COIL- | MAIN-R-COIL+ | open (OL) | power ground must not touch +12 V supply | |
| 3 | MAIN-R-COIL- | MAIN-R-OUT | open (OL) | power ground must not touch +12 V supply | |
| 4 | MAIN-R-COIL- | NEW-BATT-1 | open (OL) | power ground must not touch +12 V supply | |
| 5 | MAIN-R-COIL- | NEXUSS3-C-25 | open (OL) | power ground must not touch 5 V sensor reference | |
| 6 | MAIN-R-COIL- | OEM-T121-121 | open (OL) | power ground must not touch +12 V supply | |
| 7 | NEXUSS3-C-2 | MAIN-R-COIL+ | open (OL) | sensor ground must not touch +12 V supply | |
| 8 | NEXUSS3-C-2 | MAIN-R-OUT | open (OL) | sensor ground must not touch +12 V supply | |
| 9 | NEXUSS3-C-2 | NEW-BATT-1 | open (OL) | sensor ground must not touch +12 V supply | |
| 10 | NEXUSS3-C-2 | NEXUSS3-C-25 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 11 | NEXUSS3-C-2 | OEM-T121-121 | open (OL) | sensor ground must not touch +12 V supply | |
| 12 | NEXUSS3-C-25 | MAIN-R-OUT | open (OL) | 5 V sensor reference must not touch +12 V supply | |
| 13 | NEXUSS3-C-25 | NEW-BATT-1 | open (OL) | 5 V sensor reference must not touch +12 V supply | |
| 14 | OEM-T121-121 | NEXUSS3-C-25 | open (OL) | +12 V supply must not touch 5 V sensor reference |
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
MAIN-R
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| COIL+ | Relay coil positive (ignition-switched +12V) | — | W3 | — | 0.5 | OEM-T121-3 | — | — | — |
| COIL- | Relay coil negative (ECU low-side driver) | — | W5 | — | 0.5 | SP-GND-1 | — | — | — |
| IN | Relay contact input (battery + via main fuse) | — | W4 | — | 0.85 | NEW-BATT-1 | — | — | — |
| OUT | Relay contact output (switched +12V bus) | — | W6 | — | 0.85 | NEXUSS3-A-18 | — | — | — |
| OUT | Relay contact output (switched +12V bus) | — | W7 | — | 0.85 | NEXUSS3-A-25 | — | — | — |
NEW-BATT
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.85 | MAIN-R-IN | — | — | — |
NEW-KEYON
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W74 | — | 0.5 | NEXUSS3-A-13 | — | — | — |
NEXUSS3-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injector 1 | — | W35 | — | 0.5 | OEM-T121-96 | — | — | — |
| 10 | Battery ground | — | W10 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | Battery ground | — | W11 | — | 0.85 | SP-GND-1 | — | — | — |
| 12 | DPO 2 | — | W51 | — | 0.5 | OEM-T121-63 | — | — | — |
| 13 | Ignition switch input | — | W74 | — | 0.5 | NEW-KEYON-1 | — | — | — |
| 14 | DPO 3 | — | W52 | — | 0.5 | OEM-T121-25 | — | — | — |
| 15 | DPO 4 | — | W53 | — | 0.5 | OEM-T121-80 | — | — | — |
| 16 | DPO 5 | — | W54 | — | 0.5 | OEM-T121-104 | — | — | — |
| 17 | DPO 6 | — | W55 | — | 0.5 | OEM-T121-105 | — | — | — |
| 18 | +12V switched input | — | W6 | — | 0.85 | MAIN-R-OUT | — | — | — |
| 19 | HBO 1 | — | W40 | — | 0.5 | OEM-T121-117 | — | — | — |
| 2 | Injector 2 | — | W36 | — | 0.5 | OEM-T121-89 | — | — | — |
| 20 | HBO 2 | — | W39 | — | 0.5 | OEM-T121-118 | — | — | — |
| 21 | HBO 3 | — | — | — | — | — | — | — | — |
| 22 | HBO 4 | — | — | — | — | — | — | — | — |
| 23 | CAN 1 High | — | W72 | — | 0.5 | OEM-T121-60 | — | — | — |
| 24 | CAN 1 Low | — | W73 | — | 0.5 | OEM-T121-58 | — | — | — |
| 25 | +12V switched input | — | W7 | — | 0.85 | MAIN-R-OUT | — | — | — |
| 26 | ECR output | — | W48 | — | 0.5 | OEM-T121-65 | — | — | — |
| 27 | Ignition 1 | — | W31 | — | 0.5 | OEM-T121-102 | — | — | — |
| 28 | Ignition 2 | — | W32 | — | 0.5 | OEM-T121-95 | — | — | — |
| 29 | Ignition 3 | — | W33 | — | 0.5 | OEM-T121-103 | — | — | — |
| 3 | Injector 3 | — | W37 | — | 0.5 | OEM-T121-97 | — | — | — |
| 30 | Ignition 4 | — | W34 | — | 0.5 | OEM-T121-94 | — | — | — |
| 31 | Ignition 5 | — | — | — | — | — | — | — | — |
| 32 | Ignition 6 | — | — | — | — | — | — | — | — |
| 33 | Ignition 7 | — | — | — | — | — | — | — | — |
| 34 | Ignition 8 | — | — | — | — | — | — | — | — |
| 4 | Injector 4 | — | W38 | — | 0.5 | OEM-T121-88 | — | — | — |
| 5 | Injector 5 | — | W56 | — | 0.5 | OEM-T121-115 | — | — | — |
| 6 | Injector 6 | — | W57 | — | 0.5 | OEM-T121-22 | — | — | — |
| 7 | Injector 7 | — | W58 | — | 0.5 | OEM-T121-47 | — | — | — |
| 8 | Injector 8 | — | W59 | — | 0.5 | OEM-T121-48 | — | — | — |
| 9 | DPO 1 | — | W49 | — | 0.5 | OEM-T121-66 | — | — | — |
NEXUSS3-C
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Trigger + | — | W25 | — | 0.5 | OEM-T121-82 | — | — | — |
| 10 | AVI 1 | — | W41 | — | 0.5 | OEM-T121-53 | — | — | — |
| 11 | AVI 2 | — | W42 | — | 0.5 | OEM-T121-101 | — | — | — |
| 12 | AVI 3 | — | W43 | — | 0.5 | OEM-T121-33 | — | — | — |
| 13 | AVI 4 | — | W44 | — | 0.5 | OEM-T121-84 | — | — | — |
| 14 | AVI 5 | — | W45 | — | 0.5 | OEM-T121-35 | — | — | — |
| 15 | AVI 6 | — | W46 | — | 0.5 | OEM-T121-92 | — | — | — |
| 16 | AVI 7 | — | W47 | — | 0.5 | OEM-T121-93 | — | — | — |
| 17 | AVI 8 | — | W62 | — | 0.5 | OEM-T121-68 | — | — | — |
| 18 | AVI 9 | — | W63 | — | 0.5 | OEM-T121-69 | — | — | — |
| 19 | SPI 5 | — | W69 | — | 0.5 | OEM-T121-40 | — | — | — |
| 2 | Trigger - | — | W26 | — | 0.5 | SP-0V-1 | — | — | — |
| 20 | SPI 6 | — | W70 | — | 0.5 | OEM-T121-41 | — | — | — |
| 21 | CAN 2 High | — | — | — | — | — | — | — | — |
| 22 | CAN 2 Low | — | — | — | — | — | — | — | — |
| 23 | Knock 1 | — | W29 | — | 0.5 | OEM-T121-106 | — | — | — |
| 24 | Knock 2 | — | W30 | — | 0.5 | OEM-T121-107 | — | — | — |
| 25 | +5V | — | W24 | — | 0.5 | SP-5V1-1 | — | — | — |
| 26 | Signal ground | — | W18 | — | 0.5 | SP-0V-1 | — | — | — |
| 27 | AVI 10 | — | W64 | — | 0.5 | OEM-T121-85 | — | — | — |
| 28 | AVI 11 | — | W71 | — | 0.5 | OEM-T121-49 | — | — | — |
| 29 | WBI 1 Heater + | — | — | — | — | — | — | — | — |
| 3 | Home + | — | W27 | — | 0.5 | OEM-T121-86 | — | — | — |
| 30 | WBI 1 Input | — | — | — | — | — | — | — | — |
| 31 | WBI 1 Pump | — | W60 | — | 0.5 | OEM-T121-51 | — | — | — |
| 32 | WBI 1 Nernst | — | W61 | — | 0.5 | OEM-T121-70 | — | — | — |
| 33 | WBI 1 Heater - | — | W50 | — | 0.5 | OEM-T121-5 | — | — | — |
| 34 | WBI 1 Cal | — | — | — | — | — | — | — | — |
| 4 | Home - | — | W28 | — | 0.5 | SP-0V-1 | — | — | — |
| 5 | SPI 1 | — | W65 | — | 0.5 | OEM-T121-54 | — | — | — |
| 6 | SPI 2 | — | W66 | — | 0.5 | OEM-T121-28 | — | — | — |
| 7 | SPI 3 | — | W67 | — | 0.5 | OEM-T121-38 | — | — | — |
| 8 | SPI 4 | — | W68 | — | 0.5 | OEM-T121-39 | — | — | — |
| 9 | +8V | — | — | — | — | — | — | — | — |
OEM-T121
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU ground | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 101 | Boost pressure sensor (G31) | — | W42 | — | 0.5 | NEXUSS3-C-11 | — | — | — |
| 102 | Ignition coil 1 (N127) | — | W31 | — | 0.5 | NEXUSS3-A-27 | — | — | — |
| 103 | Ignition coil 3 (N158) | — | W33 | — | 0.5 | NEXUSS3-A-29 | — | — | — |
| 104 | Boost control solenoid (N75) | — | W54 | — | 0.5 | NEXUSS3-A-16 | — | — | — |
| 105 | Diverter valve (N249) | — | W55 | — | 0.5 | NEXUSS3-A-17 | — | — | — |
| 106 | Knock sensor 1 (G61) | — | W29 | — | 0.5 | NEXUSS3-C-23 | — | — | — |
| 107 | Knock sensor 2 (G66) | — | W30 | — | 0.5 | NEXUSS3-C-24 | — | — | — |
| 108 | Sensor ground | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 115 | VVT camshaft adjustment valve (N205) | — | W56 | — | 0.5 | NEXUSS3-A-5 | — | — | — |
| 117 | Throttle motor G186 (+) | — | W40 | — | 0.5 | NEXUSS3-A-19 | — | — | — |
| 118 | Throttle motor G186 (−) | — | W39 | — | 0.5 | NEXUSS3-A-20 | — | — | — |
| 121 | ECM + coil power (J271 relay feed) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| 2 | ECU ground | — | W9 | — | 0.85 | SP-GND-1 | — | — | — |
| 21 | ECM power (J271 relay feed) | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| 22 | Brake vacuum pump (V192) | — | W57 | — | 0.5 | NEXUSS3-A-6 | — | — | — |
| 25 | V144 Evaporative diagnostic pump (Pin 2) | — | W52 | — | 0.5 | NEXUSS3-A-14 | — | — | — |
| 27 | MAF sensor supply (G70) | — | — | — | — | — | — | — | — |
| 28 | Alternator DF terminal (charge warning) | — | W66 | — | 0.5 | NEXUSS3-C-6 | — | — | — |
| 29 | MAF sensor ground (G70) | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| 3 | Ignition switch +12V (term 15) | — | W3 | — | 0.5 | MAIN-R-COIL+ | — | — | — |
| 33 | Accelerator pedal position 1 (G79) | — | W43 | — | 0.5 | NEXUSS3-C-12 | — | — | — |
| 34 | Accelerator pedal position 1 ground (G79) | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| 35 | Accelerator pedal position 2 (G185) | — | W45 | — | 0.5 | NEXUSS3-C-14 | — | — | — |
| 36 | Accelerator pedal position 2 ground (G185) | — | W15 | — | 0.5 | SP-0V-1 | — | — | — |
| 37 | Engine speed signal (tacho to cluster) | — | — | — | — | — | — | — | — |
| 38 | Cruise control switch (E45) | — | W67 | — | 0.5 | NEXUSS3-C-7 | — | — | — |
| 39 | Clutch pedal switch (F36) | — | W68 | — | 0.5 | NEXUSS3-C-8 | — | — | — |
| 40 | A/C signal | — | W69 | — | 0.5 | NEXUSS3-C-19 | — | — | — |
| 41 | A/C signal | — | W70 | — | 0.5 | NEXUSS3-C-20 | — | — | — |
| 43 | K-line diagnostics (OBD pin 7) | — | — | — | — | — | — | — | — |
| 47 | Check engine light (MIL) | — | W58 | — | 0.5 | NEXUSS3-A-7 | — | — | — |
| 48 | EPC warning light | — | W59 | — | 0.5 | NEXUSS3-A-8 | — | — | — |
| 49 | Power steering pressure switch (F88) | — | W71 | — | 0.5 | NEXUSS3-C-28 | — | — | — |
| 5 | Wideband lambda heater (Z19) | — | W50 | — | 0.5 | NEXUSS3-C-33 | — | — | — |
| 50 | Power steering pressure switch supply (F88) | — | — | — | — | — | — | — | — |
| 51 | Wideband lambda pump (G39) | — | W60 | — | 0.5 | NEXUSS3-C-31 | — | — | — |
| 52 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 53 | MAF sensor signal (G70) | — | W41 | — | 0.5 | NEXUSS3-C-10 | — | — | — |
| 54 | Road speed signal (VSS) | — | W65 | — | 0.5 | NEXUSS3-C-5 | — | — | — |
| 55 | Brake pedal switch (F) | — | — | — | — | — | — | — | — |
| 56 | Brake pedal switch (F) | — | — | — | — | — | — | — | — |
| 57 | Cruise control switch (E45) | — | — | — | — | — | — | — | — |
| 58 | CAN bus low | — | W73 | — | 0.5 | NEXUSS3-A-24 | — | — | — |
| 60 | CAN bus high | — | W72 | — | 0.5 | NEXUSS3-A-23 | — | — | — |
| 62 | Battery constant +12V (term 30) | — | — | — | — | — | — | — | — |
| 63 | Post-cat lambda heater (Z29) | — | W51 | — | 0.5 | NEXUSS3-A-12 | — | — | — |
| 64 | EVAP canister valve (N80) | — | — | — | — | — | — | — | — |
| 65 | Fuel pump relay control | — | W48 | — | 0.5 | NEXUSS3-A-26 | — | — | — |
| 66 | Secondary-air pump relay (J299) | — | W49 | — | 0.5 | NEXUSS3-A-9 | — | — | — |
| 67 | Crash sensor signal | — | — | — | — | — | — | — | — |
| 68 | Post-cat lambda signal (G130) | — | W62 | — | 0.5 | NEXUSS3-C-17 | — | — | — |
| 69 | Post-cat lambda signal (G130) | — | W63 | — | 0.5 | NEXUSS3-C-18 | — | — | — |
| 70 | Wideband lambda Nernst signal (G39) | — | W61 | — | 0.5 | NEXUSS3-C-32 | — | — | — |
| 71 | Wideband lambda Nernst signal (G39) | — | — | — | — | — | — | — | — |
| 72 | Accelerator pedal position 1 5V supply (G79) | — | W19 | — | 0.5 | SP-5V1-1 | — | — | — |
| 73 | Accelerator pedal position 2 5V supply (G185) | — | W20 | — | 0.5 | SP-5V1-1 | — | — | — |
| 75 | Cruise control switch (E45) | — | — | — | — | — | — | — | — |
| 76 | Cruise control switch (E45) | — | — | — | — | — | — | — | — |
| 80 | V144 Evap Diagnostic Pump (Pin 1) | — | W53 | — | 0.5 | NEXUSS3-A-15 | — | — | — |
| 82 | Crank position sensor (G28) | — | W25 | — | 0.5 | NEXUSS3-C-1 | — | — | — |
| 83 | Throttle position sensor 5V supply (G187/G188) | — | W21 | — | 0.5 | SP-5V1-1 | — | — | — |
| 84 | Throttle position sensor 1 (G187) | — | W44 | — | 0.5 | NEXUSS3-C-13 | — | — | — |
| 85 | Intake air temperature (G42) | — | W64 | — | 0.5 | NEXUSS3-C-27 | — | — | — |
| 86 | Camshaft position sensor (G40) | — | W27 | — | 0.5 | NEXUSS3-C-3 | — | — | — |
| 88 | Injector 4 (N33) | — | W38 | — | 0.5 | NEXUSS3-A-4 | — | — | — |
| 89 | Injector 2 (N31) | — | W36 | — | 0.5 | NEXUSS3-A-2 | — | — | — |
| 9 | Secondary-air injection valve (N112) | — | — | — | — | — | — | — | — |
| 90 | Crank position sensor ground (G28) | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 91 | Throttle position sensor ground (G187/G188) | — | W17 | — | 0.5 | SP-0V-1 | — | — | — |
| 92 | Throttle position sensor 2 (G188) | — | W46 | — | 0.5 | NEXUSS3-C-15 | — | — | — |
| 93 | Engine coolant temperature (G62) | — | W47 | — | 0.5 | NEXUSS3-C-16 | — | — | — |
| 94 | Ignition coil 4 (N163) | — | W34 | — | 0.5 | NEXUSS3-A-30 | — | — | — |
| 95 | Ignition coil 2 (N128) | — | W32 | — | 0.5 | NEXUSS3-A-28 | — | — | — |
| 96 | Injector 1 (N30) | — | W35 | — | 0.5 | NEXUSS3-A-1 | — | — | — |
| 97 | Injector 3 (N32) | — | W37 | — | 0.5 | NEXUSS3-A-3 | — | — | — |
| 98 | Cam + boost sensor 5V supply (G40/G31) | — | W22 | — | 0.5 | SP-5V1-1 | — | — | — |
| 99 | Knock sensor 5V supply (G61/G66) | — | W23 | — | 0.5 | SP-5V1-1 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W12 | — | 0.5 | OEM-T121-108 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | OEM-T121-29 | — | — | — |
| 1 | — | — | W14 | — | 0.5 | OEM-T121-34 | — | — | — |
| 1 | — | — | W15 | — | 0.5 | OEM-T121-36 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | OEM-T121-90 | — | — | — |
| 1 | — | — | W17 | — | 0.5 | OEM-T121-91 | — | — | — |
| 1 | — | — | W18 | — | 0.5 | NEXUSS3-C-26 | — | — | — |
| 1 | — | — | W26 | — | 0.5 | NEXUSS3-C-2 | — | — | — |
| 1 | — | — | W28 | — | 0.5 | NEXUSS3-C-4 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-T121-121 | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-T121-21 | — | — | — |
SP-5V1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W19 | — | 0.5 | OEM-T121-72 | — | — | — |
| 1 | — | — | W20 | — | 0.5 | OEM-T121-73 | — | — | — |
| 1 | — | — | W21 | — | 0.5 | OEM-T121-83 | — | — | — |
| 1 | — | — | W22 | — | 0.5 | OEM-T121-98 | — | — | — |
| 1 | — | — | W23 | — | 0.5 | OEM-T121-99 | — | — | — |
| 1 | — | — | W24 | — | 0.5 | NEXUSS3-C-25 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W5 | — | 0.5 | MAIN-R-COIL- | — | — | — |
| 1 | — | — | W8 | — | 0.85 | OEM-T121-1 | — | — | — |
| 1 | — | — | W9 | — | 0.85 | OEM-T121-2 | — | — | — |
| 1 | — | — | W10 | — | 0.85 | NEXUSS3-A-10 | — | — | — |
| 1 | — | — | W11 | — | 0.85 | NEXUSS3-A-11 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-T121-1 | ECU ground | ground | MAIN-R-COIL- + NEXUSS3-A-10 + NEXUSS3-A-11 | Relay coil negative (ECU low-side driver) + Battery ground + Battery ground | ground + load | corroborated | |
| OEM-T121-101 | Boost pressure sensor (G31) | analog_in | NEXUSS3-C-11 | AVI 2 | analog_in | corroborated | |
| OEM-T121-102 | Ignition coil 1 (N127) | ignition_out | NEXUSS3-A-27 | Ignition 1 | ignition_out | corroborated | |
| OEM-T121-103 | Ignition coil 3 (N158) | ignition_out | NEXUSS3-A-29 | Ignition 3 | ignition_out | corroborated | |
| OEM-T121-104 | Boost control solenoid (N75) | low_side_out | NEXUSS3-A-16 | DPO 5 | low_side_out | corroborated | |
| OEM-T121-105 | Diverter valve (N249) | low_side_out | NEXUSS3-A-17 | DPO 6 | low_side_out | corroborated | |
| OEM-T121-106 | Knock sensor 1 (G61) | knock_in | NEXUSS3-C-23 | Knock 1 | knock_in | corroborated | |
| OEM-T121-107 | Knock sensor 2 (G66) | knock_in | NEXUSS3-C-24 | Knock 2 | knock_in | corroborated | |
| OEM-T121-108 | Sensor ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-115 | VVT camshaft adjustment valve (N205) | low_side_out | NEXUSS3-A-5 | Injector 5 | injector_out | corroborated | |
| OEM-T121-117 | Throttle motor G186 (+) | hbridge_out | NEXUSS3-A-19 | HBO 1 | hbridge_out | corroborated | |
| OEM-T121-118 | Throttle motor G186 (−) | hbridge_out | NEXUSS3-A-20 | HBO 2 | hbridge_out | corroborated | |
| OEM-T121-121 | ECM + coil power (J271 relay feed) | power_in | — | — | — | corroborated | |
| OEM-T121-2 | ECU ground | ground | MAIN-R-COIL- + NEXUSS3-A-10 + NEXUSS3-A-11 | Relay coil negative (ECU low-side driver) + Battery ground + Battery ground | ground + load | corroborated | |
| OEM-T121-21 | ECM power (J271 relay feed) | power_in | — | — | — | corroborated | |
| OEM-T121-22 | Brake vacuum pump (V192) | low_side_out | NEXUSS3-A-6 | Injector 6 | injector_out | single_source | |
| OEM-T121-25 | V144 Evaporative diagnostic pump (Pin 2) | low_side_out | NEXUSS3-A-14 | DPO 3 | low_side_out | corroborated | |
| OEM-T121-27 | MAF sensor supply (G70) | power_in | — | — | — | corroborated | |
| OEM-T121-28 | Alternator DF terminal (charge warning) | digital_in | NEXUSS3-C-6 | SPI 2 | digital_in | single_source | |
| OEM-T121-29 | MAF sensor ground (G70) | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-3 | Ignition switch +12V (term 15) | digital_in | MAIN-R-COIL+ | Relay coil positive (ignition-switched +12V) | power_in | corroborated | |
| OEM-T121-33 | Accelerator pedal position 1 (G79) | analog_in | NEXUSS3-C-12 | AVI 3 | analog_in | corroborated | |
| OEM-T121-34 | Accelerator pedal position 1 ground (G79) | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-35 | Accelerator pedal position 2 (G185) | analog_in | NEXUSS3-C-14 | AVI 5 | analog_in | corroborated | |
| OEM-T121-36 | Accelerator pedal position 2 ground (G185) | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-37 | Engine speed signal (tacho to cluster) | tacho_out | — | — | — | corroborated | |
| OEM-T121-38 | Cruise control switch (E45) | digital_in | NEXUSS3-C-7 | SPI 3 | digital_in | single_source | |
| OEM-T121-39 | Clutch pedal switch (F36) | digital_in | NEXUSS3-C-8 | SPI 4 | digital_in | single_source | |
| OEM-T121-40 | A/C signal | digital_in | NEXUSS3-C-19 | SPI 5 | digital_in | single_source | |
| OEM-T121-41 | A/C signal | digital_in | NEXUSS3-C-20 | SPI 6 | digital_in | single_source | |
| OEM-T121-43 | K-line diagnostics (OBD pin 7) | serial | — | — | — | corroborated | |
| OEM-T121-47 | Check engine light (MIL) | low_side_out | NEXUSS3-A-7 | Injector 7 | injector_out | corroborated | |
| OEM-T121-48 | EPC warning light | low_side_out | NEXUSS3-A-8 | Injector 8 | injector_out | corroborated | |
| OEM-T121-49 | Power steering pressure switch (F88) | digital_in | NEXUSS3-C-28 | AVI 11 | analog_in | single_source | |
| OEM-T121-5 | Wideband lambda heater (Z19) | low_side_out | NEXUSS3-C-33 | WBI 1 Heater - | low_side_out | corroborated | |
| OEM-T121-50 | Power steering pressure switch supply (F88) | power_in | — | — | — | single_source | |
| OEM-T121-51 | Wideband lambda pump (G39) | wb_ip | NEXUSS3-C-31 | WBI 1 Pump | wb_ip | corroborated | |
| OEM-T121-52 | Wideband lambda pump (G39) | wb_ip | — | — | — | corroborated | |
| OEM-T121-53 | MAF sensor signal (G70) | analog_in | NEXUSS3-C-10 | AVI 1 | analog_in | corroborated | |
| OEM-T121-54 | Road speed signal (VSS) | digital_in | NEXUSS3-C-5 | SPI 1 | digital_in | corroborated | |
| OEM-T121-55 | Brake pedal switch (F) | digital_in | — | — | — | single_source | |
| OEM-T121-56 | Brake pedal switch (F) | digital_in | — | — | — | single_source | |
| OEM-T121-57 | Cruise control switch (E45) | digital_in | — | — | — | single_source | |
| OEM-T121-58 | CAN bus low | can_l | NEXUSS3-A-24 | CAN 1 Low | can_l | corroborated | |
| OEM-T121-60 | CAN bus high | can_h | NEXUSS3-A-23 | CAN 1 High | can_h | corroborated | |
| OEM-T121-62 | Battery constant +12V (term 30) | power_in | — | — | — | corroborated | |
| OEM-T121-63 | Post-cat lambda heater (Z29) | low_side_out | NEXUSS3-A-12 | DPO 2 | low_side_out | corroborated | |
| OEM-T121-64 | EVAP canister valve (N80) | low_side_out | — | — | — | corroborated | |
| OEM-T121-65 | Fuel pump relay control | low_side_out | NEXUSS3-A-26 | ECR output | low_side_out | corroborated | |
| OEM-T121-66 | Secondary-air pump relay (J299) | low_side_out | NEXUSS3-A-9 | DPO 1 | low_side_out | corroborated | |
| OEM-T121-67 | Crash sensor signal | digital_in | — | — | — | single_source | |
| OEM-T121-68 | Post-cat lambda signal (G130) | lambda_nb_in | NEXUSS3-C-17 | AVI 8 | analog_in | corroborated | |
| OEM-T121-69 | Post-cat lambda signal (G130) | lambda_nb_in | NEXUSS3-C-18 | AVI 9 | analog_in | corroborated | |
| OEM-T121-70 | Wideband lambda Nernst signal (G39) | wb_vs | NEXUSS3-C-32 | WBI 1 Nernst | wb_vs | corroborated | |
| OEM-T121-71 | Wideband lambda Nernst signal (G39) | wb_vs | — | — | — | corroborated | |
| OEM-T121-72 | Accelerator pedal position 1 5V supply (G79) | vref | NEXUSS3-C-25 | +5V | vref | corroborated | |
| OEM-T121-73 | Accelerator pedal position 2 5V supply (G185) | vref | NEXUSS3-C-25 | +5V | vref | corroborated | |
| OEM-T121-75 | Cruise control switch (E45) | digital_in | — | — | — | single_source | |
| OEM-T121-76 | Cruise control switch (E45) | digital_in | — | — | — | single_source | |
| OEM-T121-80 | V144 Evap Diagnostic Pump (Pin 1) | low_side_out | NEXUSS3-A-15 | DPO 4 | low_side_out | corroborated | |
| OEM-T121-82 | Crank position sensor (G28) | trigger_in | NEXUSS3-C-1 | Trigger + | trigger_in | corroborated | |
| OEM-T121-83 | Throttle position sensor 5V supply (G187/G188) | vref | NEXUSS3-C-25 | +5V | vref | corroborated | |
| OEM-T121-84 | Throttle position sensor 1 (G187) | analog_in | NEXUSS3-C-13 | AVI 4 | analog_in | corroborated | |
| OEM-T121-85 | Intake air temperature (G42) | temp_in | NEXUSS3-C-27 | AVI 10 | analog_in | corroborated | |
| OEM-T121-86 | Camshaft position sensor (G40) | trigger_in | NEXUSS3-C-3 | Home + | trigger_in | corroborated | |
| OEM-T121-88 | Injector 4 (N33) | injector_out | NEXUSS3-A-4 | Injector 4 | injector_out | corroborated | |
| OEM-T121-89 | Injector 2 (N31) | injector_out | NEXUSS3-A-2 | Injector 2 | injector_out | corroborated | |
| OEM-T121-9 | Secondary-air injection valve (N112) | low_side_out | — | — | — | corroborated | |
| OEM-T121-90 | Crank position sensor ground (G28) | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-91 | Throttle position sensor ground (G187/G188) | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-T121-92 | Throttle position sensor 2 (G188) | analog_in | NEXUSS3-C-15 | AVI 6 | analog_in | corroborated | |
| OEM-T121-93 | Engine coolant temperature (G62) | temp_in | NEXUSS3-C-16 | AVI 7 | analog_in | corroborated | |
| OEM-T121-94 | Ignition coil 4 (N163) | ignition_out | NEXUSS3-A-30 | Ignition 4 | ignition_out | corroborated | |
| OEM-T121-95 | Ignition coil 2 (N128) | ignition_out | NEXUSS3-A-28 | Ignition 2 | ignition_out | corroborated | |
| OEM-T121-96 | Injector 1 (N30) | injector_out | NEXUSS3-A-1 | Injector 1 | injector_out | corroborated | |
| OEM-T121-97 | Injector 3 (N32) | injector_out | NEXUSS3-A-3 | Injector 3 | injector_out | corroborated | |
| OEM-T121-98 | Cam + boost sensor 5V supply (G40/G31) | vref | NEXUSS3-C-25 | +5V | vref | corroborated | |
| OEM-T121-99 | Knock sensor 5V supply (G61/G66) | vref | NEXUSS3-C-25 | +5V | vref | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-T121-121 | SP-14V-1 | 0.85 | no route | ECM + coil power (J271 relay feed) | — | |
| W2 | OEM-T121-21 | SP-14V-1 | 0.85 | no route | ECM power (J271 relay feed) | — | |
| W3 | OEM-T121-3 | MAIN-R-COIL+ | 0.5 | no route | Ignition switch +12V (term 15) | — | |
| W4 | NEW-BATT-1 | MAIN-R-IN | 0.85 | no route | Relay contact input (battery + via main fuse) | — | |
| W5 | MAIN-R-COIL- | SP-GND-1 | 0.5 | no route | Relay coil negative (ECU low-side driver) | — | |
| W6 | MAIN-R-OUT | NEXUSS3-A-18 | 0.85 | no route | Relay contact output (switched +12V bus) | — | |
| W7 | MAIN-R-OUT | NEXUSS3-A-25 | 0.85 | no route | Relay contact output (switched +12V bus) | — | |
| W8 | OEM-T121-1 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W9 | OEM-T121-2 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W10 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | no route | Battery ground | — | |
| W11 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | no route | Battery ground | — | |
| W12 | OEM-T121-108 | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W13 | OEM-T121-29 | SP-0V-1 | 0.5 | no route | MAF sensor ground (G70) | — | |
| W14 | OEM-T121-34 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 1 ground (G79) | — | |
| W15 | OEM-T121-36 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 2 ground (G185) | — | |
| W16 | OEM-T121-90 | SP-0V-1 | 0.5 | no route | Crank position sensor ground (G28) | — | |
| W17 | OEM-T121-91 | SP-0V-1 | 0.5 | no route | Throttle position sensor ground (G187/G188) | — | |
| W18 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | no route | Signal ground | — | |
| W19 | OEM-T121-72 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 1 5V supply (G79) | — | |
| W20 | OEM-T121-73 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 2 5V supply (G185) | — | |
| W21 | OEM-T121-83 | SP-5V1-1 | 0.5 | no route | Throttle position sensor 5V supply (G187/G188) | — | |
| W22 | OEM-T121-98 | SP-5V1-1 | 0.5 | no route | Cam + boost sensor 5V supply (G40/G31) | — | |
| W23 | OEM-T121-99 | SP-5V1-1 | 0.5 | no route | Knock sensor 5V supply (G61/G66) | — | |
| W24 | SP-5V1-1 | NEXUSS3-C-25 | 0.5 | no route | +5V | — | |
| W25 | OEM-T121-82 | NEXUSS3-C-1 | 0.5 | no route | Crank position sensor (G28) | — | |
| W26 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | no route | Trigger - | — | |
| W27 | OEM-T121-86 | NEXUSS3-C-3 | 0.5 | no route | Camshaft position sensor (G40) | — | |
| W28 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | no route | Home - | — | |
| W29 | OEM-T121-106 | NEXUSS3-C-23 | 0.5 | no route | Knock sensor 1 (G61) | — | |
| W30 | OEM-T121-107 | NEXUSS3-C-24 | 0.5 | no route | Knock sensor 2 (G66) | — | |
| W31 | OEM-T121-102 | NEXUSS3-A-27 | 0.5 | no route | Ignition coil 1 (N127) | — | |
| W32 | OEM-T121-95 | NEXUSS3-A-28 | 0.5 | no route | Ignition coil 2 (N128) | — | |
| W33 | OEM-T121-103 | NEXUSS3-A-29 | 0.5 | no route | Ignition coil 3 (N158) | — | |
| W34 | OEM-T121-94 | NEXUSS3-A-30 | 0.5 | no route | Ignition coil 4 (N163) | — | |
| W35 | OEM-T121-96 | NEXUSS3-A-1 | 0.5 | no route | Injector 1 (N30) | — | |
| W36 | OEM-T121-89 | NEXUSS3-A-2 | 0.5 | no route | Injector 2 (N31) | — | |
| W37 | OEM-T121-97 | NEXUSS3-A-3 | 0.5 | no route | Injector 3 (N32) | — | |
| W38 | OEM-T121-88 | NEXUSS3-A-4 | 0.5 | no route | Injector 4 (N33) | — | |
| W39 | OEM-T121-118 | NEXUSS3-A-20 | 0.5 | no route | Throttle motor G186 (−) | — | |
| W40 | OEM-T121-117 | NEXUSS3-A-19 | 0.5 | no route | Throttle motor G186 (+) | — | |
| W41 | OEM-T121-53 | NEXUSS3-C-10 | 0.5 | no route | MAF sensor signal (G70) | — | |
| W42 | OEM-T121-101 | NEXUSS3-C-11 | 0.5 | no route | Boost pressure sensor (G31) | — | |
| W43 | OEM-T121-33 | NEXUSS3-C-12 | 0.5 | no route | Accelerator pedal position 1 (G79) | — | |
| W44 | OEM-T121-84 | NEXUSS3-C-13 | 0.5 | no route | Throttle position sensor 1 (G187) | — | |
| W45 | OEM-T121-35 | NEXUSS3-C-14 | 0.5 | no route | Accelerator pedal position 2 (G185) | — | |
| W46 | OEM-T121-92 | NEXUSS3-C-15 | 0.5 | no route | Throttle position sensor 2 (G188) | — | |
| W47 | OEM-T121-93 | NEXUSS3-C-16 | 0.5 | no route | Engine coolant temperature (G62) | — | |
| W48 | OEM-T121-65 | NEXUSS3-A-26 | 0.5 | no route | Fuel pump relay control | — | |
| W49 | OEM-T121-66 | NEXUSS3-A-9 | 0.5 | no route | Secondary-air pump relay (J299) | — | |
| W50 | OEM-T121-5 | NEXUSS3-C-33 | 0.5 | no route | Wideband lambda heater (Z19) | — | |
| W51 | OEM-T121-63 | NEXUSS3-A-12 | 0.5 | no route | Post-cat lambda heater (Z29) | — | |
| W52 | OEM-T121-25 | NEXUSS3-A-14 | 0.5 | no route | V144 Evaporative diagnostic pump (Pin 2) | — | |
| W53 | OEM-T121-80 | NEXUSS3-A-15 | 0.5 | no route | V144 Evap Diagnostic Pump (Pin 1) | — | |
| W54 | OEM-T121-104 | NEXUSS3-A-16 | 0.5 | no route | Boost control solenoid (N75) | — | |
| W55 | OEM-T121-105 | NEXUSS3-A-17 | 0.5 | no route | Diverter valve (N249) | — | |
| W56 | OEM-T121-115 | NEXUSS3-A-5 | 0.5 | no route | VVT camshaft adjustment valve (N205) | — | |
| W57 | OEM-T121-22 | NEXUSS3-A-6 | 0.5 | no route | Brake vacuum pump (V192) | — | |
| W58 | OEM-T121-47 | NEXUSS3-A-7 | 0.5 | no route | Check engine light (MIL) | — | |
| W59 | OEM-T121-48 | NEXUSS3-A-8 | 0.5 | no route | EPC warning light | — | |
| W60 | OEM-T121-51 | NEXUSS3-C-31 | 0.5 | no route | Wideband lambda pump (G39) | — | |
| W61 | OEM-T121-70 | NEXUSS3-C-32 | 0.5 | no route | Wideband lambda Nernst signal (G39) | — | |
| W62 | OEM-T121-68 | NEXUSS3-C-17 | 0.5 | no route | Post-cat lambda signal (G130) | — | |
| W63 | OEM-T121-69 | NEXUSS3-C-18 | 0.5 | no route | Post-cat lambda signal (G130) | — | |
| W64 | OEM-T121-85 | NEXUSS3-C-27 | 0.5 | no route | Intake air temperature (G42) | — | |
| W65 | OEM-T121-54 | NEXUSS3-C-5 | 0.5 | no route | Road speed signal (VSS) | — | |
| W66 | OEM-T121-28 | NEXUSS3-C-6 | 0.5 | no route | Alternator DF terminal (charge warning) | — | |
| W67 | OEM-T121-38 | NEXUSS3-C-7 | 0.5 | no route | Cruise control switch (E45) | — | |
| W68 | OEM-T121-39 | NEXUSS3-C-8 | 0.5 | no route | Clutch pedal switch (F36) | — | |
| W69 | OEM-T121-40 | NEXUSS3-C-19 | 0.5 | no route | A/C signal | — | |
| W70 | OEM-T121-41 | NEXUSS3-C-20 | 0.5 | no route | A/C signal | — | |
| W71 | OEM-T121-49 | NEXUSS3-C-28 | 0.5 | no route | Power steering pressure switch (F88) | — | |
| W72 | OEM-T121-60 | NEXUSS3-A-23 | 0.5 | no route | CAN bus high | — | |
| W73 | OEM-T121-58 | NEXUSS3-A-24 | 0.5 | no route | CAN bus low | — | |
| W74 | NEW-KEYON-1 | NEXUSS3-A-13 | 0.5 | no route | Ignition switch input | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|
ECU setup sheet
| Role | Engine ref | Engine signal | Sensor | ECU point | ECU function | ECU class | Setup flag |
|---|---|---|---|---|---|---|---|
| No configured channels. | |||||||
Findings
Open (15)
| Severity | Code | Subject | Message |
|---|---|---|---|
| warn | DBW_MOTOR_CURRENT | NEXUSS3-A-19 | Cannot confirm Nexus S3 can drive the throttle motor: NEXUSS3-A-19 "HBO 1" is rated 8.0 A peak, but the motor stall current at OEM-T121-117 is unknown. Add the motor's peak current from a source, or measure the motor resistance: peak ≈ 14 V ÷ R (Hondata measured 4.9 A for a Civic Si body, 10.4 A for a ZDX body; holding current is about 1 A). |
| warn | DBW_MOTOR_CURRENT | NEXUSS3-A-20 | Cannot confirm Nexus S3 can drive the throttle motor: NEXUSS3-A-20 "HBO 2" is rated 8.0 A peak, but the motor stall current at OEM-T121-118 is unknown. Add the motor's peak current from a source, or measure the motor resistance: peak ≈ 14 V ÷ R (Hondata measured 4.9 A for a Civic Si body, 10.4 A for a ZDX body; holding current is about 1 A). |
| warn | DBW_SHARED_5V | NEXUSS3-C-25 + OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 | These 5 V supplies are separate in the stock car (OEM-T121-72 [pedal1], OEM-T121-73 [pedal2], OEM-T121-83 [tps], OEM-T121-98 [cam_boost], OEM-T121-99 [knock]) and here share one ECU 5 V (NEXUSS3-C-25). On a drive-by-wire car the OEM splits them so one short or fault can't corrupt both throttle/pedal tracks at once. Nexus S3 has 1 5 V sensor supply pin(s). All are in use, so decide: accept the shared supply (and rely on the ECU's DBW fault checks), or add a separate regulated 5 V for the sub tracks. |
| warn | LOAD_UNKNOWN | NEXUSS3-A-26 | NEXUSS3-A-26 "ECR output" drives OEM-T121-65 Fuel pump relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | NET_FAMILY | OEM-T121-49 ↔ NEXUSS3-C-28 | OEM-T121-49 "Power steering pressure switch (F88)" [digital_in] is wired to NEXUSS3-C-28 "AVI 11" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| warn | SUPPLY_GROUP | NEXUSS3-C-25 + OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 | Supplies meant to stay independent share one net: OEM-T121-72 [pedal1], OEM-T121-73 [pedal2], OEM-T121-83 [tps], OEM-T121-98 [cam_boost], OEM-T121-99 [knock]. The new ECU has no free 5 V reference, so they share one: normal on a standalone, but a short on any of these sensors drops them all. |
| info | NET_FAMILY | OEM-T121-108 ↔ NEXUSS3-C-4 | OEM-T121-108 "Sensor ground" [sensor_ground] is wired to NEXUSS3-C-4 "Home -" [trigger_in]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | NET_FAMILY | OEM-T121-115 ↔ NEXUSS3-A-5 | OEM-T121-115 "VVT camshaft adjustment valve (N205)" [low_side_out] is wired to NEXUSS3-A-5 "Injector 5" [injector_out]. Injector drivers can usually run general low-side loads; check current and PWM frequency. |
| info | NET_FAMILY | OEM-T121-22 ↔ NEXUSS3-A-6 | OEM-T121-22 "Brake vacuum pump (V192)" [low_side_out] is wired to NEXUSS3-A-6 "Injector 6" [injector_out]. Injector drivers can usually run general low-side loads; check current and PWM frequency. |
| info | NET_FAMILY | OEM-T121-3 ↔ MAIN-R-COIL+ | OEM-T121-3 "Ignition switch +12V (term 15)" [digital_in] is wired to MAIN-R-COIL+ "Relay coil positive (ignition-switched +12V)" [power_in]. Switched supply used as the ignition-on sense. |
| info | NET_FAMILY | OEM-T121-47 ↔ NEXUSS3-A-7 | OEM-T121-47 "Check engine light (MIL)" [low_side_out] is wired to NEXUSS3-A-7 "Injector 7" [injector_out]. Injector drivers can usually run general low-side loads; check current and PWM frequency. |
| info | NET_FAMILY | OEM-T121-48 ↔ NEXUSS3-A-8 | OEM-T121-48 "EPC warning light" [low_side_out] is wired to NEXUSS3-A-8 "Injector 8" [injector_out]. Injector drivers can usually run general low-side loads; check current and PWM frequency. |
| info | NET_FAMILY | OEM-T121-85 ↔ NEXUSS3-C-27 | OEM-T121-85 "Intake air temperature (G42)" [temp_in] is wired to NEXUSS3-C-27 "AVI 10" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | NET_FAMILY | OEM-T121-93 ↔ NEXUSS3-C-16 | OEM-T121-93 "Engine coolant temperature (G62)" [temp_in] is wired to NEXUSS3-C-16 "AVI 7" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | UNMAPPED | OEM | 14 optional OEM pins are not mapped: OEM-T121-27 MAF sensor supply (G70); OEM-T121-37 Engine speed signal (tacho to cluster); OEM-T121-43 K-line diagnostics (OBD pin 7); OEM-T121-50 Power steering pressure switch supply (F88); OEM-T121-52 Wideband lambda pump (G39); OEM-T121-55 Brake pedal switch (F); OEM-T121-56 Brake pedal switch (F); OEM-T121-57 Cruise control switch (E45); OEM-T121-64 EVAP canister valve (N80); OEM-T121-67 Crash sensor signal; OEM-T121-71 Wideband lambda Nernst signal (G39); OEM-T121-75 Cruise control switch (E45); OEM-T121-76 Cruise control switch (E45); OEM-T121-9 Secondary-air injection valve (N112) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-T121-62 | Battery-constant (memory) feed of the stock ECU: the new ECU has no such input, so it is not needed. | mapping-proposal |
Notes
Auto-mapped by auto_map() from the library pin data on 2026-10-23. Review every wire against both manuals before building. Not wired: - OEM-T121 62: Battery constant +12V (term 30): Haltech Nexus S3 has no battery-constant memory input; not needed - OEM-T121 64: EVAP canister valve (N80): no free low_side/relay_control/heater_low_side/ls_hs/injector on Haltech Nexus S3 - OEM-T121 9: Secondary-air injection valve (N112): no free low_side/relay_control/heater_low_side/ls_hs/injector on Haltech Nexus S3 - OEM-T121 37: Engine speed signal (tacho to cluster): no free tacho/frequency_out/low_side/ls_hs on Haltech Nexus S3 - OEM-T121 52: Wideband lambda pump (G39): no free wb_ip on Haltech Nexus S3 - OEM-T121 71: Wideband lambda Nernst signal (G39): no free wb_vs on Haltech Nexus S3 - OEM-T121 55: Brake pedal switch (F): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 56: Brake pedal switch (F): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 57: Cruise control switch (E45): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 67: Crash sensor signal: no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 75: Cruise control switch (E45): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 76: Cruise control switch (E45): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-T121 43: K-line diagnostics (OBD pin 7): no free k_line on Haltech Nexus S3 - OEM-T121 27: MAF sensor supply (G70): no rule for class sensor_supply_in; wire by hand - OEM-T121 50: Power steering pressure switch supply (F88): no rule for class sensor_supply_in; wire by hand
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | Emtron SL4/SL6/SL8 pinout pages | https://docs.emtronaustralia.com.au/engine-management/wiring/index.html | archive | 2026-10-05 | e52b3da9996a |
| 4 | vendor_doc | Haltech: Nexus S3 Plug 'n' Play adapter QSG (Subaru WRX/STI ADM, HT-186300) — ECU Connector A & C pinout | https://www.haltech.com/product/ht-186300-nexus-s3-plug-n-play-adapter-harness/ | archive | 2026-10-05 | 3cab7cd337c2 |
| 4 | vendor_doc | Haltech: Nexus S3/S2 ECU Overview (QSG) — specifications | https://store.haltech.com/product/ht-213000-nexus-s3-ecu-only/ | archive | 2026-10-05 | 388299668207 |
| 3 | community_copy | NefMoto: ME7.5 1.8t Golf AWP ECU wiring breakdown (Bentley-derived) | https://nefariousmotorsports.com/forum/index.php?topic=18710.0 | — | — | — |
| 3 | community_copy | NefMoto: ME7.5 ECU bench-flashing power/ground pins | http://nefmoto.com/wiki/index.php?title=ECU_Bench_Flashing | — | — | — |
| 3 | forum | rusEFI Mazda Miata 2002 engine wiring | https://github.com/rusefi/rusefi/wiki/Mazda-Miata-2002 | archive | 2026-10-05 | cc3cae670408 |
| 3 | community_copy | vwressources: Bosch Motronic ME7.5 (AMK/ARY/AUQ/ARX/AUM) T121 pinout | https://www.vwressources.planethoster.world/me75_pinout.html | — | — | — |