MX-5 Miata NB2 2001-05 (BP-Z3, VVT) → Haltech Nexus S3 HT-213000 (auto)
MX-5 Miata NB2 2001-05 (BP-Z3, VVT) — Haltech — Nexus S3
Drawn by Michael Gnankou · Rev 0 · proposal · 2026-10-08
Before you start
| Status | proposal · not yet verified: nobody has reported building and running this harness |
|---|---|
| Open errors | none |
| Size of the job | 54 wires · 8 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-2-P | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-4-AF | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | NEXUSS3-A-18 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | SP-14V-1 | NEXUSS3-A-25 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-3-B | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-4-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-4-O | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-4-L | NEXUSS3-C-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-3-Y | NEXUSS3-C-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-3-V | NEXUSS3-C-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-4-M | NEXUSS3-C-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-3-F | NEXUSS3-A-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-3-I | NEXUSS3-A-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-2-A | NEXUSS3-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-2-D | NEXUSS3-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-2-G | NEXUSS3-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-2-J | NEXUSS3-A-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-2-B | NEXUSS3-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-2-C | NEXUSS3-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-2-K | NEXUSS3-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-2-M | NEXUSS3-A-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-3-H | NEXUSS3-A-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-3-J | NEXUSS3-C-33 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-3-P | NEXUSS3-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-2-Q | NEXUSS3-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-2-E | NEXUSS3-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-2-F | NEXUSS3-A-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-2-H | NEXUSS3-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-2-I | NEXUSS3-A-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-2-N | NEXUSS3-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-2-R | NEXUSS3-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-3-D | NEXUSS3-A-21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-3-E | NEXUSS3-A-22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-4-X | NEXUSS3-C-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-4-V | NEXUSS3-C-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-4-AA | NEXUSS3-C-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-4-W | NEXUSS3-C-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W44 | OEM-4-P | NEXUSS3-C-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W45 | OEM-4-N | NEXUSS3-C-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W46 | OEM-4-AD | NEXUSS3-C-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W47 | OEM-3-T | NEXUSS3-C-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W48 | OEM-3-S | NEXUSS3-C-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W49 | OEM-4-B | NEXUSS3-C-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W50 | OEM-4-C | NEXUSS3-C-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W51 | OEM-4-F | NEXUSS3-C-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W52 | OEM-4-H | NEXUSS3-C-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W53 | OEM-4-I | NEXUSS3-C-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W54 | OEM-4-J | NEXUSS3-C-18 | 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 | NEXUSS3-A-18 | NEXUSS3-A-10 | open (OL) | +12 V supply must not touch power ground | |
| 2 | NEXUSS3-A-18 | NEXUSS3-C-2 | open (OL) | +12 V supply must not touch sensor ground | |
| 3 | NEXUSS3-C-25 | NEXUSS3-C-2 | open (OL) | 5 V sensor reference must not touch sensor ground | |
| 4 | NEXUSS3-A-10 | NEXUSS3-C-25 | open (OL) | power ground must not touch 5 V sensor reference | |
| 5 | NEXUSS3-A-18 | NEXUSS3-C-25 | open (OL) | +12 V supply must not touch 5 V sensor reference |
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
NEXUSS3-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injector 1 | — | W20 | — | 0.5 | OEM-2-A | — | — | — |
| 10 | Battery ground | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | Battery ground | — | W9 | — | 0.85 | SP-GND-1 | — | — | — |
| 12 | DPO 2 | — | W26 | — | 0.5 | OEM-2-K | — | — | — |
| 13 | Ignition switch input | — | — | — | — | — | — | — | — |
| 14 | DPO 3 | — | W27 | — | 0.5 | OEM-2-M | — | — | — |
| 15 | DPO 4 | — | W28 | — | 0.5 | OEM-3-H | — | — | — |
| 16 | DPO 5 | — | W30 | — | 0.5 | OEM-3-P | — | — | — |
| 17 | DPO 6 | — | W31 | — | 0.5 | OEM-2-Q | — | — | — |
| 18 | +12V switched input | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 19 | HBO 1 | — | W36 | — | 0.5 | OEM-2-N | — | — | — |
| 2 | Injector 2 | — | W21 | — | 0.5 | OEM-2-D | — | — | — |
| 20 | HBO 2 | — | W37 | — | 0.5 | OEM-2-R | — | — | — |
| 21 | HBO 3 | — | W38 | — | 0.5 | OEM-3-D | — | — | — |
| 22 | HBO 4 | — | W39 | — | 0.5 | OEM-3-E | — | — | — |
| 23 | CAN 1 High | — | — | — | — | — | — | — | — |
| 24 | CAN 1 Low | — | — | — | — | — | — | — | — |
| 25 | +12V switched input | — | W4 | — | 0.85 | SP-14V-1 | — | — | — |
| 26 | ECR output | — | W24 | — | 0.5 | OEM-2-B | — | — | — |
| 27 | Ignition 1 | — | W18 | — | 0.5 | OEM-3-F | — | — | — |
| 28 | Ignition 2 | — | W19 | — | 0.5 | OEM-3-I | — | — | — |
| 29 | Ignition 3 | — | — | — | — | — | — | — | — |
| 3 | Injector 3 | — | W22 | — | 0.5 | OEM-2-G | — | — | — |
| 30 | Ignition 4 | — | — | — | — | — | — | — | — |
| 31 | Ignition 5 | — | — | — | — | — | — | — | — |
| 32 | Ignition 6 | — | — | — | — | — | — | — | — |
| 33 | Ignition 7 | — | — | — | — | — | — | — | — |
| 34 | Ignition 8 | — | — | — | — | — | — | — | — |
| 4 | Injector 4 | — | W23 | — | 0.5 | OEM-2-J | — | — | — |
| 5 | Injector 5 | — | W32 | — | 0.5 | OEM-2-E | — | — | — |
| 6 | Injector 6 | — | W33 | — | 0.5 | OEM-2-F | — | — | — |
| 7 | Injector 7 | — | W34 | — | 0.5 | OEM-2-H | — | — | — |
| 8 | Injector 8 | — | W35 | — | 0.5 | OEM-2-I | — | — | — |
| 9 | DPO 1 | — | W25 | — | 0.5 | OEM-2-C | — | — | — |
NEXUSS3-C
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Trigger + | — | W13 | — | 0.5 | OEM-3-Y | — | — | — |
| 10 | AVI 1 | — | W40 | — | 0.5 | OEM-4-X | — | — | — |
| 11 | AVI 2 | — | W41 | — | 0.5 | OEM-4-V | — | — | — |
| 12 | AVI 3 | — | W42 | — | 0.5 | OEM-4-AA | — | — | — |
| 13 | AVI 4 | — | W43 | — | 0.5 | OEM-4-W | — | — | — |
| 14 | AVI 5 | — | W44 | — | 0.5 | OEM-4-P | — | — | — |
| 15 | AVI 6 | — | W45 | — | 0.5 | OEM-4-N | — | — | — |
| 16 | AVI 7 | — | W46 | — | 0.5 | OEM-4-AD | — | — | — |
| 17 | AVI 8 | — | W53 | — | 0.5 | OEM-4-I | — | — | — |
| 18 | AVI 9 | — | W54 | — | 0.5 | OEM-4-J | — | — | — |
| 19 | SPI 5 | — | W51 | — | 0.5 | OEM-4-F | — | — | — |
| 2 | Trigger - | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| 20 | SPI 6 | — | W52 | — | 0.5 | OEM-4-H | — | — | — |
| 21 | CAN 2 High | — | — | — | — | — | — | — | — |
| 22 | CAN 2 Low | — | — | — | — | — | — | — | — |
| 23 | Knock 1 | — | W17 | — | 0.5 | OEM-4-M | — | — | — |
| 24 | Knock 2 | — | — | — | — | — | — | — | — |
| 25 | +5V | — | W12 | — | 0.5 | OEM-4-L | — | — | — |
| 26 | Signal ground | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| 27 | AVI 10 | — | — | — | — | — | — | — | — |
| 28 | AVI 11 | — | — | — | — | — | — | — | — |
| 29 | WBI 1 Heater + | — | — | — | — | — | — | — | — |
| 3 | Home + | — | W15 | — | 0.5 | OEM-3-V | — | — | — |
| 30 | WBI 1 Input | — | — | — | — | — | — | — | — |
| 31 | WBI 1 Pump | — | — | — | — | — | — | — | — |
| 32 | WBI 1 Nernst | — | — | — | — | — | — | — | — |
| 33 | WBI 1 Heater - | — | W29 | — | 0.5 | OEM-3-J | — | — | — |
| 34 | WBI 1 Cal | — | — | — | — | — | — | — | — |
| 4 | Home - | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 5 | SPI 1 | — | W47 | — | 0.5 | OEM-3-T | — | — | — |
| 6 | SPI 2 | — | W48 | — | 0.5 | OEM-3-S | — | — | — |
| 7 | SPI 3 | — | W49 | — | 0.5 | OEM-4-B | — | — | — |
| 8 | SPI 4 | — | W50 | — | 0.5 | OEM-4-C | — | — | — |
| 9 | +8V | — | — | — | — | — | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Injector 1 | — | W20 | — | 0.5 | NEXUSS3-A-1 | — | — | — |
| B | Cooling fan relay | — | W24 | — | 0.5 | NEXUSS3-A-26 | — | — | — |
| C | Condenser fan relay | — | W25 | — | 0.5 | NEXUSS3-A-9 | — | — | — |
| D | Injector 2 | — | W21 | — | 0.5 | NEXUSS3-A-2 | — | — | — |
| E | EGR valve | — | W32 | — | 0.5 | NEXUSS3-A-5 | — | — | — |
| F | EGR valve | — | W33 | — | 0.5 | NEXUSS3-A-6 | — | — | — |
| G | Injector 3 | — | W22 | — | 0.5 | NEXUSS3-A-3 | — | — | — |
| H | EGR valve | — | W34 | — | 0.5 | NEXUSS3-A-7 | — | — | — |
| I | EGR valve | — | W35 | — | 0.5 | NEXUSS3-A-8 | — | — | — |
| J | Injector 4 | — | W23 | — | 0.5 | NEXUSS3-A-4 | — | — | — |
| K | A/C clutch relay | — | W26 | — | 0.5 | NEXUSS3-A-12 | — | — | — |
| M | Fuel pump relay | — | W27 | — | 0.5 | NEXUSS3-A-14 | — | — | — |
| N | VTCS solenoid (intake butterflies) | — | W36 | — | 0.5 | NEXUSS3-A-19 | — | — | — |
| P | ISC valve +14V feed | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| Q | ISC valve low side | — | W31 | — | 0.5 | NEXUSS3-A-17 | — | — | — |
| R | Malfunction indicator lamp (MIL) | — | W37 | — | 0.5 | NEXUSS3-A-20 | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| B | Power ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| D | EGR boost solenoid | — | W38 | — | 0.5 | NEXUSS3-A-21 | — | — | — |
| E | Charcoal canister purge | — | W39 | — | 0.5 | NEXUSS3-A-22 | — | — | — |
| F | Ignition 1 (coils 1+4, wasted spark) | — | W18 | — | 0.5 | NEXUSS3-A-27 | — | — | — |
| H | Main relay | — | W28 | — | 0.5 | NEXUSS3-A-15 | — | — | — |
| I | Ignition 2 (coils 2+3, wasted spark) | — | W19 | — | 0.5 | NEXUSS3-A-28 | — | — | — |
| J | Front O2 heater | — | W29 | — | 0.5 | NEXUSS3-C-33 | — | — | — |
| M | Alternator control | — | — | — | — | — | — | — | — |
| O | Tachometer output | — | — | — | — | — | — | — | — |
| P | Rear O2 heater | — | W30 | — | 0.5 | NEXUSS3-A-16 | — | — | — |
| S | Immobiliser | — | W48 | — | 0.5 | NEXUSS3-C-6 | — | — | — |
| T | Vehicle speed | — | W47 | — | 0.5 | NEXUSS3-C-5 | — | — | — |
| U | Charge lamp | — | — | — | — | — | — | — | — |
| V | Cam position (CMP) | — | W15 | — | 0.5 | NEXUSS3-C-3 | — | — | — |
| Y | Crank position (CKP) | — | W13 | — | 0.5 | NEXUSS3-C-1 | — | — | — |
OEM-4
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| AA | Rear O2 signal | — | W42 | — | 0.5 | NEXUSS3-C-12 | — | — | — |
| AD | Fuel level | — | W46 | — | 0.5 | NEXUSS3-C-16 | — | — | — |
| AF | ECU power +14V (main relay) | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| AG | Constant +12V | — | — | — | — | — | — | — | — |
| B | Brake switch | — | W49 | — | 0.5 | NEXUSS3-C-7 | — | — | — |
| C | Power steering pressure switch | — | W50 | — | 0.5 | NEXUSS3-C-8 | — | — | — |
| D | VVT oil-control solenoid | — | — | — | — | — | — | — | — |
| F | A/C request | — | W51 | — | 0.5 | NEXUSS3-C-19 | — | — | — |
| H | Neutral switch | — | W52 | — | 0.5 | NEXUSS3-C-20 | — | — | — |
| I | Clutch switch | — | W53 | — | 0.5 | NEXUSS3-C-17 | — | — | — |
| J | VTCS vacuum switch | — | W54 | — | 0.5 | NEXUSS3-C-18 | — | — | — |
| L | +5V sensor supply | — | W12 | — | 0.5 | NEXUSS3-C-25 | — | — | — |
| M | Knock sensor | — | W17 | — | 0.5 | NEXUSS3-C-23 | — | — | — |
| N | Intake air temperature (IAT) | — | W45 | — | 0.5 | NEXUSS3-C-15 | — | — | — |
| O | Signal ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| P | Coolant temperature (ECT) | — | W44 | — | 0.5 | NEXUSS3-C-14 | — | — | — |
| V | Throttle position (TPS) | — | W41 | — | 0.5 | NEXUSS3-C-11 | — | — | — |
| W | Front O2 signal | — | W43 | — | 0.5 | NEXUSS3-C-13 | — | — | — |
| X | Mass air flow (MAF) | — | W40 | — | 0.5 | NEXUSS3-C-10 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W10 | — | 0.5 | OEM-4-O | — | — | — |
| 1 | — | — | W11 | — | 0.5 | NEXUSS3-C-26 | — | — | — |
| 1 | — | — | W14 | — | 0.5 | NEXUSS3-C-2 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | NEXUSS3-C-4 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-2-P | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-4-AF | — | — | — |
| 1 | — | — | W3 | — | 0.85 | NEXUSS3-A-18 | — | — | — |
| 1 | — | — | W4 | — | 0.85 | NEXUSS3-A-25 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W5 | — | 0.85 | OEM-3-A | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-3-B | — | — | — |
| 1 | — | — | W7 | — | 0.85 | OEM-4-A | — | — | — |
| 1 | — | — | W8 | — | 0.85 | NEXUSS3-A-10 | — | — | — |
| 1 | — | — | W9 | — | 0.85 | NEXUSS3-A-11 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-2-A | Injector 1 | injector_out | NEXUSS3-A-1 | Injector 1 | injector_out | single_source | |
| OEM-2-B | Cooling fan relay | low_side_out | NEXUSS3-A-26 | ECR output | low_side_out | single_source | |
| OEM-2-C | Condenser fan relay | low_side_out | NEXUSS3-A-9 | DPO 1 | low_side_out | single_source | |
| OEM-2-D | Injector 2 | injector_out | NEXUSS3-A-2 | Injector 2 | injector_out | single_source | |
| OEM-2-E | EGR valve | low_side_out | NEXUSS3-A-5 | Injector 5 | injector_out | single_source | |
| OEM-2-F | EGR valve | low_side_out | NEXUSS3-A-6 | Injector 6 | injector_out | single_source | |
| OEM-2-G | Injector 3 | injector_out | NEXUSS3-A-3 | Injector 3 | injector_out | single_source | |
| OEM-2-H | EGR valve | low_side_out | NEXUSS3-A-7 | Injector 7 | injector_out | single_source | |
| OEM-2-I | EGR valve | low_side_out | NEXUSS3-A-8 | Injector 8 | injector_out | single_source | |
| OEM-2-J | Injector 4 | injector_out | NEXUSS3-A-4 | Injector 4 | injector_out | single_source | |
| OEM-2-K | A/C clutch relay | low_side_out | NEXUSS3-A-12 | DPO 2 | low_side_out | single_source | |
| OEM-2-M | Fuel pump relay | low_side_out | NEXUSS3-A-14 | DPO 3 | low_side_out | single_source | |
| OEM-2-N | VTCS solenoid (intake butterflies) | low_side_out | NEXUSS3-A-19 | HBO 1 | hbridge_out | single_source | |
| OEM-2-P | ISC valve +14V feed | power_in | NEXUSS3-A-18 + NEXUSS3-A-25 | +12V switched input + +12V switched input | power_in | single_source | |
| OEM-2-Q | ISC valve low side | low_side_out | NEXUSS3-A-17 | DPO 6 | low_side_out | single_source | |
| OEM-2-R | Malfunction indicator lamp (MIL) | low_side_out | NEXUSS3-A-20 | HBO 2 | hbridge_out | single_source | |
| OEM-3-A | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-B | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-D | EGR boost solenoid | low_side_out | NEXUSS3-A-21 | HBO 3 | hbridge_out | single_source | |
| OEM-3-E | Charcoal canister purge | low_side_out | NEXUSS3-A-22 | HBO 4 | hbridge_out | single_source | |
| OEM-3-F | Ignition 1 (coils 1+4, wasted spark) | ignition_out | NEXUSS3-A-27 | Ignition 1 | ignition_out | single_source | |
| OEM-3-H | Main relay | low_side_out | NEXUSS3-A-15 | DPO 4 | low_side_out | single_source | |
| OEM-3-I | Ignition 2 (coils 2+3, wasted spark) | ignition_out | NEXUSS3-A-28 | Ignition 2 | ignition_out | single_source | |
| OEM-3-J | Front O2 heater | low_side_out | NEXUSS3-C-33 | WBI 1 Heater - | low_side_out | single_source | |
| OEM-3-M | Alternator control | low_side_out | — | — | — | single_source | |
| OEM-3-O | Tachometer output | tacho_out | — | — | — | single_source | |
| OEM-3-P | Rear O2 heater | low_side_out | NEXUSS3-A-16 | DPO 5 | low_side_out | single_source | |
| OEM-3-S | Immobiliser | digital_in | NEXUSS3-C-6 | SPI 2 | digital_in | single_source | |
| OEM-3-T | Vehicle speed | digital_in | NEXUSS3-C-5 | SPI 1 | digital_in | single_source | |
| OEM-3-U | Charge lamp | low_side_out | — | — | — | single_source | |
| OEM-3-V | Cam position (CMP) | trigger_in | NEXUSS3-C-3 | Home + | trigger_in | single_source | |
| OEM-3-Y | Crank position (CKP) | trigger_in | NEXUSS3-C-1 | Trigger + | trigger_in | single_source | |
| OEM-4-A | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-4-AA | Rear O2 signal | lambda_nb_in | NEXUSS3-C-12 | AVI 3 | analog_in | single_source | |
| OEM-4-AD | Fuel level | analog_in | NEXUSS3-C-16 | AVI 7 | analog_in | single_source | |
| OEM-4-AF | ECU power +14V (main relay) | power_in | NEXUSS3-A-18 + NEXUSS3-A-25 | +12V switched input + +12V switched input | power_in | single_source | |
| OEM-4-AG | Constant +12V | power_in | — | — | — | single_source | |
| OEM-4-B | Brake switch | digital_in | NEXUSS3-C-7 | SPI 3 | digital_in | single_source | |
| OEM-4-C | Power steering pressure switch | digital_in | NEXUSS3-C-8 | SPI 4 | digital_in | single_source | |
| OEM-4-D | VVT oil-control solenoid | low_side_out | — | — | — | single_source | |
| OEM-4-F | A/C request | digital_in | NEXUSS3-C-19 | SPI 5 | digital_in | single_source | |
| OEM-4-H | Neutral switch | digital_in | NEXUSS3-C-20 | SPI 6 | digital_in | single_source | |
| OEM-4-I | Clutch switch | digital_in | NEXUSS3-C-17 | AVI 8 | analog_in | single_source | |
| OEM-4-J | VTCS vacuum switch | digital_in | NEXUSS3-C-18 | AVI 9 | analog_in | single_source | |
| OEM-4-L | +5V sensor supply | vref | NEXUSS3-C-25 | +5V | vref | single_source | |
| OEM-4-M | Knock sensor | knock_in | NEXUSS3-C-23 | Knock 1 | knock_in | single_source | |
| OEM-4-N | Intake air temperature (IAT) | temp_in | NEXUSS3-C-15 | AVI 6 | analog_in | single_source | |
| OEM-4-O | Signal ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | single_source | |
| OEM-4-P | Coolant temperature (ECT) | temp_in | NEXUSS3-C-14 | AVI 5 | analog_in | single_source | |
| OEM-4-V | Throttle position (TPS) | analog_in | NEXUSS3-C-11 | AVI 2 | analog_in | single_source | |
| OEM-4-W | Front O2 signal | lambda_nb_in | NEXUSS3-C-13 | AVI 4 | analog_in | single_source | |
| OEM-4-X | Mass air flow (MAF) | analog_in | NEXUSS3-C-10 | AVI 1 | analog_in | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-2-P | SP-14V-1 | 0.85 | no route | ISC valve +14V feed | — | |
| W2 | OEM-4-AF | SP-14V-1 | 0.85 | no route | ECU power +14V (main relay) | — | |
| W3 | SP-14V-1 | NEXUSS3-A-18 | 0.85 | no route | +12V switched input | — | |
| W4 | SP-14V-1 | NEXUSS3-A-25 | 0.85 | no route | +12V switched input | — | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W6 | OEM-3-B | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W7 | OEM-4-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W8 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | no route | Battery ground | — | |
| W9 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | no route | Battery ground | — | |
| W10 | OEM-4-O | SP-0V-1 | 0.5 | no route | Signal ground | — | |
| W11 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | no route | Signal ground | — | |
| W12 | OEM-4-L | NEXUSS3-C-25 | 0.5 | no route | +5V sensor supply | — | |
| W13 | OEM-3-Y | NEXUSS3-C-1 | 0.5 | no route | Crank position (CKP) | — | |
| W14 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | no route | Trigger - | — | |
| W15 | OEM-3-V | NEXUSS3-C-3 | 0.5 | no route | Cam position (CMP) | — | |
| W16 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | no route | Home - | — | |
| W17 | OEM-4-M | NEXUSS3-C-23 | 0.5 | no route | Knock sensor | — | |
| W18 | OEM-3-F | NEXUSS3-A-27 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W19 | OEM-3-I | NEXUSS3-A-28 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W20 | OEM-2-A | NEXUSS3-A-1 | 0.5 | no route | Injector 1 | — | |
| W21 | OEM-2-D | NEXUSS3-A-2 | 0.5 | no route | Injector 2 | — | |
| W22 | OEM-2-G | NEXUSS3-A-3 | 0.5 | no route | Injector 3 | — | |
| W23 | OEM-2-J | NEXUSS3-A-4 | 0.5 | no route | Injector 4 | — | |
| W24 | OEM-2-B | NEXUSS3-A-26 | 0.5 | no route | Cooling fan relay | — | |
| W25 | OEM-2-C | NEXUSS3-A-9 | 0.5 | no route | Condenser fan relay | — | |
| W26 | OEM-2-K | NEXUSS3-A-12 | 0.5 | no route | A/C clutch relay | — | |
| W27 | OEM-2-M | NEXUSS3-A-14 | 0.5 | no route | Fuel pump relay | — | |
| W28 | OEM-3-H | NEXUSS3-A-15 | 0.5 | no route | Main relay | — | |
| W29 | OEM-3-J | NEXUSS3-C-33 | 0.5 | no route | Front O2 heater | — | |
| W30 | OEM-3-P | NEXUSS3-A-16 | 0.5 | no route | Rear O2 heater | — | |
| W31 | OEM-2-Q | NEXUSS3-A-17 | 0.5 | no route | ISC valve low side | — | |
| W32 | OEM-2-E | NEXUSS3-A-5 | 0.5 | no route | EGR valve | — | |
| W33 | OEM-2-F | NEXUSS3-A-6 | 0.5 | no route | EGR valve | — | |
| W34 | OEM-2-H | NEXUSS3-A-7 | 0.5 | no route | EGR valve | — | |
| W35 | OEM-2-I | NEXUSS3-A-8 | 0.5 | no route | EGR valve | — | |
| W36 | OEM-2-N | NEXUSS3-A-19 | 0.5 | no route | VTCS solenoid (intake butterflies) | — | |
| W37 | OEM-2-R | NEXUSS3-A-20 | 0.5 | no route | Malfunction indicator lamp (MIL) | — | |
| W38 | OEM-3-D | NEXUSS3-A-21 | 0.5 | no route | EGR boost solenoid | — | |
| W39 | OEM-3-E | NEXUSS3-A-22 | 0.5 | no route | Charcoal canister purge | — | |
| W40 | OEM-4-X | NEXUSS3-C-10 | 0.5 | no route | Mass air flow (MAF) | — | |
| W41 | OEM-4-V | NEXUSS3-C-11 | 0.5 | no route | Throttle position (TPS) | — | |
| W42 | OEM-4-AA | NEXUSS3-C-12 | 0.5 | no route | Rear O2 signal | — | |
| W43 | OEM-4-W | NEXUSS3-C-13 | 0.5 | no route | Front O2 signal | — | |
| W44 | OEM-4-P | NEXUSS3-C-14 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W45 | OEM-4-N | NEXUSS3-C-15 | 0.5 | no route | Intake air temperature (IAT) | — | |
| W46 | OEM-4-AD | NEXUSS3-C-16 | 0.5 | no route | Fuel level | — | |
| W47 | OEM-3-T | NEXUSS3-C-5 | 0.5 | no route | Vehicle speed | — | |
| W48 | OEM-3-S | NEXUSS3-C-6 | 0.5 | no route | Immobiliser | — | |
| W49 | OEM-4-B | NEXUSS3-C-7 | 0.5 | no route | Brake switch | — | |
| W50 | OEM-4-C | NEXUSS3-C-8 | 0.5 | no route | Power steering pressure switch | — | |
| W51 | OEM-4-F | NEXUSS3-C-19 | 0.5 | no route | A/C request | — | |
| W52 | OEM-4-H | NEXUSS3-C-20 | 0.5 | no route | Neutral switch | — | |
| W53 | OEM-4-I | NEXUSS3-C-17 | 0.5 | no route | Clutch switch | — | |
| W54 | OEM-4-J | NEXUSS3-C-18 | 0.5 | no route | VTCS vacuum switch | — |
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 | LOAD_UNKNOWN | NEXUSS3-A-26 | NEXUSS3-A-26 "ECR output" drives OEM-2-B Cooling fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | NET_FAMILY | OEM-2-N ↔ NEXUSS3-A-19 | OEM-2-N "VTCS solenoid (intake butterflies)" [low_side_out] is wired to NEXUSS3-A-19 "HBO 1" [hbridge_out]. A half-bridge can act as a low-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-2-R ↔ NEXUSS3-A-20 | OEM-2-R "Malfunction indicator lamp (MIL)" [low_side_out] is wired to NEXUSS3-A-20 "HBO 2" [hbridge_out]. A half-bridge can act as a low-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-3-D ↔ NEXUSS3-A-21 | OEM-3-D "EGR boost solenoid" [low_side_out] is wired to NEXUSS3-A-21 "HBO 3" [hbridge_out]. A half-bridge can act as a low-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-3-E ↔ NEXUSS3-A-22 | OEM-3-E "Charcoal canister purge" [low_side_out] is wired to NEXUSS3-A-22 "HBO 4" [hbridge_out]. A half-bridge can act as a low-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-4-I ↔ NEXUSS3-C-17 | OEM-4-I "Clutch switch" [digital_in] is wired to NEXUSS3-C-17 "AVI 8" [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 | NET_FAMILY | OEM-4-J ↔ NEXUSS3-C-18 | OEM-4-J "VTCS vacuum switch" [digital_in] is wired to NEXUSS3-C-18 "AVI 9" [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. |
| info | NET_FAMILY | NEXUSS3-C-2 ↔ NEXUSS3-C-26 | NEXUSS3-C-2 "Trigger -" [trigger_in] is wired to NEXUSS3-C-26 "Signal ground" [sensor_ground]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | NET_FAMILY | OEM-2-E ↔ NEXUSS3-A-5 | OEM-2-E "EGR valve" [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-2-F ↔ NEXUSS3-A-6 | OEM-2-F "EGR valve" [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-2-H ↔ NEXUSS3-A-7 | OEM-2-H "EGR valve" [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-2-I ↔ NEXUSS3-A-8 | OEM-2-I "EGR valve" [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-4-N ↔ NEXUSS3-C-15 | OEM-4-N "Intake air temperature (IAT)" [temp_in] is wired to NEXUSS3-C-15 "AVI 6" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | NET_FAMILY | OEM-4-P ↔ NEXUSS3-C-14 | OEM-4-P "Coolant temperature (ECT)" [temp_in] is wired to NEXUSS3-C-14 "AVI 5" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | UNMAPPED | OEM | 4 optional OEM pins are not mapped: OEM-3-M Alternator control; OEM-3-O Tachometer output; OEM-3-U Charge lamp; OEM-4-D VVT oil-control solenoid |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-4-AG | 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 2026-10-06. Review every wire against both manuals before building. Not wired: - OEM-4 AG: Constant +12V: Haltech Nexus S3 has no battery-constant input; not needed - OEM-3 M: Alternator control: no free low_side/ls_hs/injector/hbridge on Haltech Nexus S3 - OEM-3 U: Charge lamp: no free low_side/ls_hs/injector/hbridge on Haltech Nexus S3 - OEM-4 D: VVT oil-control solenoid: no free low_side/ls_hs/injector/hbridge on Haltech Nexus S3 - OEM-3 O: Tachometer output: no free tacho/frequency_out/low_side/ls_hs on Haltech Nexus S3 - NEXUSS3-A 13: Ignition switch input: not fed (the stock ECU has no ignition-sense pin); feed it from a switched-ignition source
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 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 |
| 4 | vendor_doc | Link G4X MX5NB2X install manual (NB2 2001-05) | https://linkecu.com/documentation/MX5XNB2.pdf | archive | 2026-10-05 | 741efdd9f2c8 |