Mazda RX-7 FC 1986-92 (13B-T Turbo II) → Haltech Nexus S3 HT-213000 (auto)
Mazda RX-7 FC 1986-92 (13B-T Turbo II) — 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 | 50 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-3-I | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | SP-14V-1 | NEXUSS3-A-18 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | NEXUSS3-A-25 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-2-R | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-3-G | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-1-P | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-1-Q | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-2-C | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-2-A | NEXUSS3-C-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-1-T | NEXUSS3-C-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-1-N | NEXUSS3-C-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-1-R | NEXUSS3-C-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-1-U | NEXUSS3-A-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-1-V | NEXUSS3-A-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-1-X | NEXUSS3-A-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-3-E | NEXUSS3-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-3-H | NEXUSS3-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-3-C | NEXUSS3-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-3-F | NEXUSS3-A-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-1-F | NEXUSS3-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-3-D | NEXUSS3-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-1-C | NEXUSS3-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-1-S | NEXUSS3-A-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-2-K | NEXUSS3-A-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-2-M | NEXUSS3-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-2-N | NEXUSS3-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-2-O | NEXUSS3-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-2-P | NEXUSS3-A-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-2-Q | NEXUSS3-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-2-E | NEXUSS3-C-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-2-B | NEXUSS3-C-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-2-G | NEXUSS3-C-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-2-D | NEXUSS3-C-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-2-I | NEXUSS3-C-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-2-J | NEXUSS3-C-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-2-L | NEXUSS3-C-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-2-F | NEXUSS3-C-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W44 | OEM-2-H | NEXUSS3-C-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W45 | OEM-1-O | NEXUSS3-C-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W46 | OEM-1-E | NEXUSS3-C-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W47 | OEM-1-G | NEXUSS3-C-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W48 | OEM-1-H | NEXUSS3-C-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W49 | OEM-1-L | NEXUSS3-C-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W50 | OEM-3-B | NEXUSS3-C-20 | 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-C-25 | NEXUSS3-A-10 | open (OL) | 5 V sensor reference must not touch power ground | |
| 2 | NEXUSS3-A-10 | NEXUSS3-A-18 | open (OL) | power ground must not touch +12 V supply | |
| 3 | NEXUSS3-C-2 | NEXUSS3-A-18 | open (OL) | sensor ground must not touch +12 V supply | |
| 4 | NEXUSS3-C-2 | NEXUSS3-C-25 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 5 | NEXUSS3-C-25 | NEXUSS3-A-18 | open (OL) | 5 V sensor reference must not touch +12 V supply |
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 | — | W22 | — | 0.5 | OEM-3-E | — | — | — |
| 10 | Battery ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | Battery ground | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 12 | DPO 2 | — | W28 | — | 0.5 | OEM-1-C | — | — | — |
| 13 | Ignition switch input | — | — | — | — | — | — | — | — |
| 14 | DPO 3 | — | W29 | — | 0.5 | OEM-1-S | — | — | — |
| 15 | DPO 4 | — | W30 | — | 0.5 | OEM-2-K | — | — | — |
| 16 | DPO 5 | — | W31 | — | 0.5 | OEM-2-M | — | — | — |
| 17 | DPO 6 | — | W32 | — | 0.5 | OEM-2-N | — | — | — |
| 18 | +12V switched input | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| 19 | HBO 1 | — | — | — | — | — | — | — | — |
| 2 | Injector 2 | — | W23 | — | 0.5 | OEM-3-H | — | — | — |
| 20 | HBO 2 | — | — | — | — | — | — | — | — |
| 21 | HBO 3 | — | — | — | — | — | — | — | — |
| 22 | HBO 4 | — | — | — | — | — | — | — | — |
| 23 | CAN 1 High | — | — | — | — | — | — | — | — |
| 24 | CAN 1 Low | — | — | — | — | — | — | — | — |
| 25 | +12V switched input | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 26 | ECR output | — | W26 | — | 0.5 | OEM-1-F | — | — | — |
| 27 | Ignition 1 | — | W19 | — | 0.5 | OEM-1-U | — | — | — |
| 28 | Ignition 2 | — | W20 | — | 0.5 | OEM-1-V | — | — | — |
| 29 | Ignition 3 | — | W21 | — | 0.5 | OEM-1-X | — | — | — |
| 3 | Injector 3 | — | W24 | — | 0.5 | OEM-3-C | — | — | — |
| 30 | Ignition 4 | — | — | — | — | — | — | — | — |
| 31 | Ignition 5 | — | — | — | — | — | — | — | — |
| 32 | Ignition 6 | — | — | — | — | — | — | — | — |
| 33 | Ignition 7 | — | — | — | — | — | — | — | — |
| 34 | Ignition 8 | — | — | — | — | — | — | — | — |
| 4 | Injector 4 | — | W25 | — | 0.5 | OEM-3-F | — | — | — |
| 5 | Injector 5 | — | W33 | — | 0.5 | OEM-2-O | — | — | — |
| 6 | Injector 6 | — | W34 | — | 0.5 | OEM-2-P | — | — | — |
| 7 | Injector 7 | — | W35 | — | 0.5 | OEM-2-Q | — | — | — |
| 8 | Injector 8 | — | — | — | — | — | — | — | — |
| 9 | DPO 1 | — | W27 | — | 0.5 | OEM-3-D | — | — | — |
NEXUSS3-C
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Trigger + | — | W14 | — | 0.5 | OEM-1-T | — | — | — |
| 10 | AVI 1 | — | W36 | — | 0.5 | OEM-2-E | — | — | — |
| 11 | AVI 2 | — | W37 | — | 0.5 | OEM-2-B | — | — | — |
| 12 | AVI 3 | — | W38 | — | 0.5 | OEM-2-G | — | — | — |
| 13 | AVI 4 | — | W39 | — | 0.5 | OEM-2-D | — | — | — |
| 14 | AVI 5 | — | W40 | — | 0.5 | OEM-2-I | — | — | — |
| 15 | AVI 6 | — | W41 | — | 0.5 | OEM-2-J | — | — | — |
| 16 | AVI 7 | — | W42 | — | 0.5 | OEM-2-L | — | — | — |
| 17 | AVI 8 | — | W43 | — | 0.5 | OEM-2-F | — | — | — |
| 18 | AVI 9 | — | W44 | — | 0.5 | OEM-2-H | — | — | — |
| 19 | SPI 5 | — | W49 | — | 0.5 | OEM-1-L | — | — | — |
| 2 | Trigger - | — | W15 | — | 0.5 | SP-0V-1 | — | — | — |
| 20 | SPI 6 | — | W50 | — | 0.5 | OEM-3-B | — | — | — |
| 21 | CAN 2 High | — | — | — | — | — | — | — | — |
| 22 | CAN 2 Low | — | — | — | — | — | — | — | — |
| 23 | Knock 1 | — | W18 | — | 0.5 | OEM-1-R | — | — | — |
| 24 | Knock 2 | — | — | — | — | — | — | — | — |
| 25 | +5V | — | W13 | — | 0.5 | OEM-2-A | — | — | — |
| 26 | Signal ground | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 27 | AVI 10 | — | — | — | — | — | — | — | — |
| 28 | AVI 11 | — | — | — | — | — | — | — | — |
| 29 | WBI 1 Heater + | — | — | — | — | — | — | — | — |
| 3 | Home + | — | W16 | — | 0.5 | OEM-1-N | — | — | — |
| 30 | WBI 1 Input | — | — | — | — | — | — | — | — |
| 31 | WBI 1 Pump | — | — | — | — | — | — | — | — |
| 32 | WBI 1 Nernst | — | — | — | — | — | — | — | — |
| 33 | WBI 1 Heater - | — | — | — | — | — | — | — | — |
| 34 | WBI 1 Cal | — | — | — | — | — | — | — | — |
| 4 | Home - | — | W17 | — | 0.5 | SP-0V-1 | — | — | — |
| 5 | SPI 1 | — | W45 | — | 0.5 | OEM-1-O | — | — | — |
| 6 | SPI 2 | — | W46 | — | 0.5 | OEM-1-E | — | — | — |
| 7 | SPI 3 | — | W47 | — | 0.5 | OEM-1-G | — | — | — |
| 8 | SPI 4 | — | W48 | — | 0.5 | OEM-1-H | — | — | — |
| 9 | +8V | — | — | — | — | — | — | — | — |
OEM-1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| C | Air bypass solenoid | — | W28 | — | 0.5 | NEXUSS3-A-12 | — | — | — |
| E | A/C request | — | W46 | — | 0.5 | NEXUSS3-C-6 | — | — | — |
| F | A/C clutch relay | — | W26 | — | 0.5 | NEXUSS3-A-26 | — | — | — |
| G | Neutral switch | — | W47 | — | 0.5 | NEXUSS3-C-7 | — | — | — |
| H | Water temperature switch | — | W48 | — | 0.5 | NEXUSS3-C-8 | — | — | — |
| L | Clutch switch | — | W49 | — | 0.5 | NEXUSS3-C-19 | — | — | — |
| M | Ignition feedback (tacho) | — | — | — | — | — | — | — | — |
| N | CAS 2-tooth (G, cam) | — | W16 | — | 0.5 | NEXUSS3-C-3 | — | — | — |
| O | Vehicle speed (mileage sensor) | — | W45 | — | 0.5 | NEXUSS3-C-5 | — | — | — |
| P | CAS ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| Q | CAS ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| R | Knock input | — | W18 | — | 0.5 | NEXUSS3-C-23 | — | — | — |
| S | Port air valve | — | W29 | — | 0.5 | NEXUSS3-A-14 | — | — | — |
| T | CAS 24-tooth (NE, crank) | — | W14 | — | 0.5 | NEXUSS3-C-1 | — | — | — |
| U | Ignition select (trailing rotor) | — | W19 | — | 0.5 | NEXUSS3-A-27 | — | — | — |
| V | Ignition leading | — | W20 | — | 0.5 | NEXUSS3-A-28 | — | — | — |
| X | Ignition trailing | — | W21 | — | 0.5 | NEXUSS3-A-29 | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | 5V sensor supply | — | W13 | — | 0.5 | NEXUSS3-C-25 | — | — | — |
| B | MAP (pressure) signal | — | W37 | — | 0.5 | NEXUSS3-C-11 | — | — | — |
| C | Sensor ground | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| D | O2 sensor signal | — | W39 | — | 0.5 | NEXUSS3-C-13 | — | — | — |
| E | Airflow signal (AFM) | — | W36 | — | 0.5 | NEXUSS3-C-10 | — | — | — |
| F | Variable resistor (tuning) | — | W43 | — | 0.5 | NEXUSS3-C-17 | — | — | — |
| G | Throttle position (TPS) | — | W38 | — | 0.5 | NEXUSS3-C-12 | — | — | — |
| H | Atmospheric pressure (ATP) | — | W44 | — | 0.5 | NEXUSS3-C-18 | — | — | — |
| I | Coolant temperature (ECT) | — | W40 | — | 0.5 | NEXUSS3-C-14 | — | — | — |
| J | Inlet air temperature (IAT) | — | W41 | — | 0.5 | NEXUSS3-C-15 | — | — | — |
| K | Turbo control valve (boost) | — | W30 | — | 0.5 | NEXUSS3-A-15 | — | — | — |
| L | Manifold air temperature (MAT) | — | W42 | — | 0.5 | NEXUSS3-C-16 | — | — | — |
| M | Pressure regulator control valve | — | W31 | — | 0.5 | NEXUSS3-A-16 | — | — | — |
| N | EGR valve | — | W32 | — | 0.5 | NEXUSS3-A-17 | — | — | — |
| O | Switching valve | — | W33 | — | 0.5 | NEXUSS3-A-5 | — | — | — |
| P | Relief valve | — | W34 | — | 0.5 | NEXUSS3-A-6 | — | — | — |
| Q | Idle control (BAC) | — | W35 | — | 0.5 | NEXUSS3-A-7 | — | — | — |
| R | Power ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| B | Starter input | — | W50 | — | 0.5 | NEXUSS3-C-20 | — | — | — |
| C | Primary injector 2 | — | W24 | — | 0.5 | NEXUSS3-A-3 | — | — | — |
| D | Starter inhibit / fuel pump control | — | W27 | — | 0.5 | NEXUSS3-A-9 | — | — | — |
| E | Primary injector 1 | — | W22 | — | 0.5 | NEXUSS3-A-1 | — | — | — |
| F | Secondary injector 2 | — | W25 | — | 0.5 | NEXUSS3-A-4 | — | — | — |
| G | Power ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| H | Secondary injector 1 | — | W23 | — | 0.5 | NEXUSS3-A-2 | — | — | — |
| I | Ignition power (+12V via main relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| J | Battery constant (+12V) | — | — | — | — | — | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W9 | — | 0.5 | OEM-1-P | — | — | — |
| 1 | — | — | W10 | — | 0.5 | OEM-1-Q | — | — | — |
| 1 | — | — | W11 | — | 0.5 | OEM-2-C | — | — | — |
| 1 | — | — | W12 | — | 0.5 | NEXUSS3-C-26 | — | — | — |
| 1 | — | — | W15 | — | 0.5 | NEXUSS3-C-2 | — | — | — |
| 1 | — | — | W17 | — | 0.5 | NEXUSS3-C-4 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-3-I | — | — | — |
| 1 | — | — | W2 | — | 0.85 | NEXUSS3-A-18 | — | — | — |
| 1 | — | — | W3 | — | 0.85 | NEXUSS3-A-25 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.85 | OEM-2-R | — | — | — |
| 1 | — | — | W5 | — | 0.85 | OEM-3-A | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-3-G | — | — | — |
| 1 | — | — | W7 | — | 0.85 | NEXUSS3-A-10 | — | — | — |
| 1 | — | — | W8 | — | 0.85 | NEXUSS3-A-11 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-1-C | Air bypass solenoid | low_side_out | NEXUSS3-A-12 | DPO 2 | low_side_out | single_source | |
| OEM-1-E | A/C request | digital_in | NEXUSS3-C-6 | SPI 2 | digital_in | single_source | |
| OEM-1-F | A/C clutch relay | low_side_out | NEXUSS3-A-26 | ECR output | low_side_out | single_source | |
| OEM-1-G | Neutral switch | digital_in | NEXUSS3-C-7 | SPI 3 | digital_in | corroborated | |
| OEM-1-H | Water temperature switch | digital_in | NEXUSS3-C-8 | SPI 4 | digital_in | corroborated | |
| OEM-1-L | Clutch switch | digital_in | NEXUSS3-C-19 | SPI 5 | digital_in | single_source | |
| OEM-1-M | Ignition feedback (tacho) | tacho_out | — | — | — | single_source | |
| OEM-1-N | CAS 2-tooth (G, cam) | trigger_in | NEXUSS3-C-3 | Home + | trigger_in | corroborated | |
| OEM-1-O | Vehicle speed (mileage sensor) | digital_in | NEXUSS3-C-5 | SPI 1 | digital_in | single_source | |
| OEM-1-P | CAS ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-1-Q | CAS ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | corroborated | |
| OEM-1-R | Knock input | knock_in | NEXUSS3-C-23 | Knock 1 | knock_in | corroborated | |
| OEM-1-S | Port air valve | low_side_out | NEXUSS3-A-14 | DPO 3 | low_side_out | single_source | |
| OEM-1-T | CAS 24-tooth (NE, crank) | trigger_in | NEXUSS3-C-1 | Trigger + | trigger_in | corroborated | |
| OEM-1-U | Ignition select (trailing rotor) | ignition_out | NEXUSS3-A-27 | Ignition 1 | ignition_out | corroborated | |
| OEM-1-V | Ignition leading | ignition_out | NEXUSS3-A-28 | Ignition 2 | ignition_out | corroborated | |
| OEM-1-X | Ignition trailing | ignition_out | NEXUSS3-A-29 | Ignition 3 | ignition_out | single_source | |
| OEM-2-A | 5V sensor supply | vref | NEXUSS3-C-25 | +5V | vref | single_source | |
| OEM-2-B | MAP (pressure) signal | analog_in | NEXUSS3-C-11 | AVI 2 | analog_in | single_source | |
| OEM-2-C | Sensor ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | single_source | |
| OEM-2-D | O2 sensor signal | lambda_nb_in | NEXUSS3-C-13 | AVI 4 | analog_in | single_source | |
| OEM-2-E | Airflow signal (AFM) | analog_in | NEXUSS3-C-10 | AVI 1 | analog_in | single_source | |
| OEM-2-F | Variable resistor (tuning) | analog_in | NEXUSS3-C-17 | AVI 8 | analog_in | single_source | |
| OEM-2-G | Throttle position (TPS) | analog_in | NEXUSS3-C-12 | AVI 3 | analog_in | single_source | |
| OEM-2-H | Atmospheric pressure (ATP) | analog_in | NEXUSS3-C-18 | AVI 9 | analog_in | single_source | |
| OEM-2-I | Coolant temperature (ECT) | temp_in | NEXUSS3-C-14 | AVI 5 | analog_in | single_source | |
| OEM-2-J | Inlet air temperature (IAT) | temp_in | NEXUSS3-C-15 | AVI 6 | analog_in | single_source | |
| OEM-2-K | Turbo control valve (boost) | low_side_out | NEXUSS3-A-15 | DPO 4 | low_side_out | single_source | |
| OEM-2-L | Manifold air temperature (MAT) | temp_in | NEXUSS3-C-16 | AVI 7 | analog_in | single_source | |
| OEM-2-M | Pressure regulator control valve | low_side_out | NEXUSS3-A-16 | DPO 5 | low_side_out | single_source | |
| OEM-2-N | EGR valve | low_side_out | NEXUSS3-A-17 | DPO 6 | low_side_out | single_source | |
| OEM-2-O | Switching valve | low_side_out | NEXUSS3-A-5 | Injector 5 | injector_out | single_source | |
| OEM-2-P | Relief valve | low_side_out | NEXUSS3-A-6 | Injector 6 | injector_out | single_source | |
| OEM-2-Q | Idle control (BAC) | low_side_out | NEXUSS3-A-7 | Injector 7 | injector_out | single_source | |
| OEM-2-R | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-A | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-B | Starter input | digital_in | NEXUSS3-C-20 | SPI 6 | digital_in | single_source | |
| OEM-3-C | Primary injector 2 | injector_out | NEXUSS3-A-3 | Injector 3 | injector_out | single_source | |
| OEM-3-D | Starter inhibit / fuel pump control | low_side_out | NEXUSS3-A-9 | DPO 1 | low_side_out | single_source | |
| OEM-3-E | Primary injector 1 | injector_out | NEXUSS3-A-1 | Injector 1 | injector_out | single_source | |
| OEM-3-F | Secondary injector 2 | injector_out | NEXUSS3-A-4 | Injector 4 | injector_out | single_source | |
| OEM-3-G | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-H | Secondary injector 1 | injector_out | NEXUSS3-A-2 | Injector 2 | injector_out | single_source | |
| OEM-3-I | Ignition power (+12V via main relay) | power_in | NEXUSS3-A-18 + NEXUSS3-A-25 | +12V switched input + +12V switched input | power_in | single_source | |
| OEM-3-J | Battery constant (+12V) | power_in | — | — | — | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-3-I | SP-14V-1 | 0.85 | no route | Ignition power (+12V via main relay) | — | |
| W2 | SP-14V-1 | NEXUSS3-A-18 | 0.85 | no route | +12V switched input | — | |
| W3 | SP-14V-1 | NEXUSS3-A-25 | 0.85 | no route | +12V switched input | — | |
| W4 | OEM-2-R | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W6 | OEM-3-G | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W7 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | no route | Battery ground | — | |
| W8 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | no route | Battery ground | — | |
| W9 | OEM-1-P | SP-0V-1 | 0.5 | no route | CAS ground | — | |
| W10 | OEM-1-Q | SP-0V-1 | 0.5 | no route | CAS ground | — | |
| W11 | OEM-2-C | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W12 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | no route | Signal ground | — | |
| W13 | OEM-2-A | NEXUSS3-C-25 | 0.5 | no route | 5V sensor supply | — | |
| W14 | OEM-1-T | NEXUSS3-C-1 | 0.5 | no route | CAS 24-tooth (NE, crank) | — | |
| W15 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | no route | Trigger - | — | |
| W16 | OEM-1-N | NEXUSS3-C-3 | 0.5 | no route | CAS 2-tooth (G, cam) | — | |
| W17 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | no route | Home - | — | |
| W18 | OEM-1-R | NEXUSS3-C-23 | 0.5 | no route | Knock input | — | |
| W19 | OEM-1-U | NEXUSS3-A-27 | 0.5 | no route | Ignition select (trailing rotor) | — | |
| W20 | OEM-1-V | NEXUSS3-A-28 | 0.5 | no route | Ignition leading | — | |
| W21 | OEM-1-X | NEXUSS3-A-29 | 0.5 | no route | Ignition trailing | — | |
| W22 | OEM-3-E | NEXUSS3-A-1 | 0.5 | no route | Primary injector 1 | — | |
| W23 | OEM-3-H | NEXUSS3-A-2 | 0.5 | no route | Secondary injector 1 | — | |
| W24 | OEM-3-C | NEXUSS3-A-3 | 0.5 | no route | Primary injector 2 | — | |
| W25 | OEM-3-F | NEXUSS3-A-4 | 0.5 | no route | Secondary injector 2 | — | |
| W26 | OEM-1-F | NEXUSS3-A-26 | 0.5 | no route | A/C clutch relay | — | |
| W27 | OEM-3-D | NEXUSS3-A-9 | 0.5 | no route | Starter inhibit / fuel pump control | — | |
| W28 | OEM-1-C | NEXUSS3-A-12 | 0.5 | no route | Air bypass solenoid | — | |
| W29 | OEM-1-S | NEXUSS3-A-14 | 0.5 | no route | Port air valve | — | |
| W30 | OEM-2-K | NEXUSS3-A-15 | 0.5 | no route | Turbo control valve (boost) | — | |
| W31 | OEM-2-M | NEXUSS3-A-16 | 0.5 | no route | Pressure regulator control valve | — | |
| W32 | OEM-2-N | NEXUSS3-A-17 | 0.5 | no route | EGR valve | — | |
| W33 | OEM-2-O | NEXUSS3-A-5 | 0.5 | no route | Switching valve | — | |
| W34 | OEM-2-P | NEXUSS3-A-6 | 0.5 | no route | Relief valve | — | |
| W35 | OEM-2-Q | NEXUSS3-A-7 | 0.5 | no route | Idle control (BAC) | — | |
| W36 | OEM-2-E | NEXUSS3-C-10 | 0.5 | no route | Airflow signal (AFM) | — | |
| W37 | OEM-2-B | NEXUSS3-C-11 | 0.5 | no route | MAP (pressure) signal | — | |
| W38 | OEM-2-G | NEXUSS3-C-12 | 0.5 | no route | Throttle position (TPS) | — | |
| W39 | OEM-2-D | NEXUSS3-C-13 | 0.5 | no route | O2 sensor signal | — | |
| W40 | OEM-2-I | NEXUSS3-C-14 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W41 | OEM-2-J | NEXUSS3-C-15 | 0.5 | no route | Inlet air temperature (IAT) | — | |
| W42 | OEM-2-L | NEXUSS3-C-16 | 0.5 | no route | Manifold air temperature (MAT) | — | |
| W43 | OEM-2-F | NEXUSS3-C-17 | 0.5 | no route | Variable resistor (tuning) | — | |
| W44 | OEM-2-H | NEXUSS3-C-18 | 0.5 | no route | Atmospheric pressure (ATP) | — | |
| W45 | OEM-1-O | NEXUSS3-C-5 | 0.5 | no route | Vehicle speed (mileage sensor) | — | |
| W46 | OEM-1-E | NEXUSS3-C-6 | 0.5 | no route | A/C request | — | |
| W47 | OEM-1-G | NEXUSS3-C-7 | 0.5 | no route | Neutral switch | — | |
| W48 | OEM-1-H | NEXUSS3-C-8 | 0.5 | no route | Water temperature switch | — | |
| W49 | OEM-1-L | NEXUSS3-C-19 | 0.5 | no route | Clutch switch | — | |
| W50 | OEM-3-B | NEXUSS3-C-20 | 0.5 | no route | Starter 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 (9)
| Severity | Code | Subject | Message |
|---|---|---|---|
| warn | LOAD_UNKNOWN | NEXUSS3-A-26 | NEXUSS3-A-26 "ECR output" drives OEM-1-F A/C clutch relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| info | NET_FAMILY | NEXUSS3-C-26 ↔ NEXUSS3-C-4 | NEXUSS3-C-26 "Signal 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-2-I ↔ NEXUSS3-C-14 | OEM-2-I "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 | NET_FAMILY | OEM-2-J ↔ NEXUSS3-C-15 | OEM-2-J "Inlet 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-2-L ↔ NEXUSS3-C-16 | OEM-2-L "Manifold air temperature (MAT)" [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 | NET_FAMILY | OEM-2-O ↔ NEXUSS3-A-5 | OEM-2-O "Switching 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-P ↔ NEXUSS3-A-6 | OEM-2-P "Relief 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-Q ↔ NEXUSS3-A-7 | OEM-2-Q "Idle control (BAC)" [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 | UNMAPPED | OEM | 1 optional OEM pins are not mapped: OEM-1-M Ignition feedback (tacho) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-3-J | 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-3 J: Battery constant (+12V): Haltech Nexus S3 has no battery-constant input; not needed - OEM-1 M: Ignition feedback (tacho): 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 | Adaptronic: Select RX7 Series 4 FC Turbo plug-in pinout | https://www.rx7club.com/attachments/adaptronic-engine-mgmt-aus-311/543323d1411579751-need-pin-out-diagram-s5-pnp-rx7_s4_sel_pinout.pdf | — | — | — |
| 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 |
| 2 | forum | MSExtra: FC3S CAS wiring (NE/G) | https://www.msextra.com/forums/viewtopic.php?p=279694 | — | — | — |
| 2 | forum | NoPistons: S4 Turbo II main harness wiring (ECU plug, colours only) | https://www.nopistons.com/1st-generation-specific-16/thinking-putting-89-13bt-sa22-66354/page2/ | — | — | — |