Toyota Supra A70 1986-92 (7M-GTE) → Haltech Nexus S3 HT-213000 (auto)
Toyota Supra A70 1986-92 (7M-GTE) — Haltech — Nexus S3
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-12
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 | draft · not yet verified: nobody has reported building and running this harness |
|---|---|
| Open errors | 2: read the Findings page before cutting any wire |
| Size of the job | 14 wires · 7 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-A-26 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-B-9 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-A-12 | NEXUSS3-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-A-11 | NEXUSS3-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-A-25 | NEXUSS3-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-B-11 | NEXUSS3-C-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-B-4 | NEXUSS3-C-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-B-2 | NEXUSS3-C-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-B-6 | NEXUSS3-C-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-B-3 | NEXUSS3-C-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-D-9 | NEXUSS3-C-6 | 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 |
|---|---|---|---|---|---|
| No supply/ground nets found to cross-check. | |||||
If any reading doesn't match, stop and get help before powering up.
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 | — | W6 | — | 0.5 | OEM-A-12 | — | — | — |
| 10 | Battery ground | — | W2 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | Battery ground | — | W3 | — | 0.85 | SP-GND-1 | — | — | — |
| 12 | DPO 2 | — | — | — | — | — | — | — | — |
| 13 | Ignition switch input | — | — | — | — | — | — | — | — |
| 14 | DPO 3 | — | — | — | — | — | — | — | — |
| 15 | DPO 4 | — | — | — | — | — | — | — | — |
| 16 | DPO 5 | — | — | — | — | — | — | — | — |
| 17 | DPO 6 | — | — | — | — | — | — | — | — |
| 18 | +12V switched input | — | — | — | — | — | — | — | — |
| 19 | HBO 1 | — | — | — | — | — | — | — | — |
| 2 | Injector 2 | — | W7 | — | 0.5 | OEM-A-11 | — | — | — |
| 20 | HBO 2 | — | — | — | — | — | — | — | — |
| 21 | HBO 3 | — | — | — | — | — | — | — | — |
| 22 | HBO 4 | — | — | — | — | — | — | — | — |
| 23 | CAN 1 High | — | — | — | — | — | — | — | — |
| 24 | CAN 1 Low | — | — | — | — | — | — | — | — |
| 25 | +12V switched input | — | — | — | — | — | — | — | — |
| 26 | ECR output | — | — | — | — | — | — | — | — |
| 27 | Ignition 1 | — | — | — | — | — | — | — | — |
| 28 | Ignition 2 | — | — | — | — | — | — | — | — |
| 29 | Ignition 3 | — | — | — | — | — | — | — | — |
| 3 | Injector 3 | — | W8 | — | 0.5 | OEM-A-25 | — | — | — |
| 30 | Ignition 4 | — | — | — | — | — | — | — | — |
| 31 | Ignition 5 | — | — | — | — | — | — | — | — |
| 32 | Ignition 6 | — | — | — | — | — | — | — | — |
| 33 | Ignition 7 | — | — | — | — | — | — | — | — |
| 34 | Ignition 8 | — | — | — | — | — | — | — | — |
| 4 | Injector 4 | — | — | — | — | — | — | — | — |
| 5 | Injector 5 | — | — | — | — | — | — | — | — |
| 6 | Injector 6 | — | — | — | — | — | — | — | — |
| 7 | Injector 7 | — | — | — | — | — | — | — | — |
| 8 | Injector 8 | — | — | — | — | — | — | — | — |
| 9 | DPO 1 | — | — | — | — | — | — | — | — |
NEXUSS3-C
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Trigger + | — | — | — | — | — | — | — | — |
| 10 | AVI 1 | — | W9 | — | 0.5 | OEM-B-11 | — | — | — |
| 11 | AVI 2 | — | W10 | — | 0.5 | OEM-B-4 | — | — | — |
| 12 | AVI 3 | — | W12 | — | 0.5 | OEM-B-6 | — | — | — |
| 13 | AVI 4 | — | W13 | — | 0.5 | OEM-B-3 | — | — | — |
| 14 | AVI 5 | — | — | — | — | — | — | — | — |
| 15 | AVI 6 | — | — | — | — | — | — | — | — |
| 16 | AVI 7 | — | — | — | — | — | — | — | — |
| 17 | AVI 8 | — | — | — | — | — | — | — | — |
| 18 | AVI 9 | — | — | — | — | — | — | — | — |
| 19 | SPI 5 | — | — | — | — | — | — | — | — |
| 2 | Trigger - | — | — | — | — | — | — | — | — |
| 20 | SPI 6 | — | — | — | — | — | — | — | — |
| 21 | CAN 2 High | — | — | — | — | — | — | — | — |
| 22 | CAN 2 Low | — | — | — | — | — | — | — | — |
| 23 | Knock 1 | — | — | — | — | — | — | — | — |
| 24 | Knock 2 | — | — | — | — | — | — | — | — |
| 25 | +5V | — | — | — | — | — | — | — | — |
| 26 | Signal ground | — | W5 | — | 0.5 | SP-0V-1 | — | — | — |
| 27 | AVI 10 | — | — | — | — | — | — | — | — |
| 28 | AVI 11 | — | — | — | — | — | — | — | — |
| 29 | WBI 1 Heater + | — | — | — | — | — | — | — | — |
| 3 | Home + | — | — | — | — | — | — | — | — |
| 30 | WBI 1 Input | — | — | — | — | — | — | — | — |
| 31 | WBI 1 Pump | — | — | — | — | — | — | — | — |
| 32 | WBI 1 Nernst | — | — | — | — | — | — | — | — |
| 33 | WBI 1 Heater - | — | — | — | — | — | — | — | — |
| 34 | WBI 1 Cal | — | — | — | — | — | — | — | — |
| 4 | Home - | — | — | — | — | — | — | — | — |
| 5 | SPI 1 | — | W11 | — | 0.5 | OEM-B-2 | — | — | — |
| 6 | SPI 2 | — | W14 | — | 0.5 | OEM-D-9 | — | — | — |
| 7 | SPI 3 | — | — | — | — | — | — | — | — |
| 8 | SPI 4 | — | — | — | — | — | — | — | — |
| 9 | +8V | — | — | — | — | — | — | — | — |
OEM-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 11 | Injectors 2 & 6 (No.20) | — | W7 | — | 0.5 | NEXUSS3-A-2 | — | — | — |
| 12 | Injectors 1 & 4 (No.10) | — | W6 | — | 0.5 | NEXUSS3-A-1 | — | — | — |
| 25 | Injectors 3 & 5 (No.30) | — | W8 | — | 0.5 | NEXUSS3-A-3 | — | — | — |
| 26 | Power ground (E01/E02) | — | W1 | — | 0.85 | SP-GND-1 | — | — | — |
OEM-B
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 11 | Throttle position sensor (VTA) | — | W9 | — | 0.5 | NEXUSS3-C-10 | — | — | — |
| 2 | Karman-vortex AFM signal (KS) | — | W11 | — | 0.5 | NEXUSS3-C-5 | — | — | — |
| 3 | Intake air temp (THA) | — | W13 | — | 0.5 | NEXUSS3-C-13 | — | — | — |
| 4 | Coolant temp (THW) | — | W10 | — | 0.5 | NEXUSS3-C-11 | — | — | — |
| 6 | Primary O2 sensor (OX1) | — | W12 | — | 0.5 | NEXUSS3-C-12 | — | — | — |
| 9 | Sensor ground (E2) | — | W4 | — | 0.5 | SP-0V-1 | — | — | — |
OEM-D
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 9 | Vehicle speed sensor (SPD) | — | W14 | — | 0.5 | NEXUSS3-C-6 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.5 | OEM-B-9 | — | — | — |
| 1 | — | — | W5 | — | 0.5 | NEXUSS3-C-26 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-A-26 | — | — | — |
| 1 | — | — | W2 | — | 0.85 | NEXUSS3-A-10 | — | — | — |
| 1 | — | — | W3 | — | 0.85 | NEXUSS3-A-11 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-A-11 | Injectors 2 & 6 (No.20) | injector_out | NEXUSS3-A-2 | Injector 2 | injector_out | corroborated | |
| OEM-A-12 | Injectors 1 & 4 (No.10) | injector_out | NEXUSS3-A-1 | Injector 1 | injector_out | corroborated | |
| OEM-A-25 | Injectors 3 & 5 (No.30) | injector_out | NEXUSS3-A-3 | Injector 3 | injector_out | corroborated | |
| OEM-A-26 | Power ground (E01/E02) | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | corroborated | |
| OEM-B-11 | Throttle position sensor (VTA) | analog_in | NEXUSS3-C-10 | AVI 1 | analog_in | corroborated | |
| OEM-B-2 | Karman-vortex AFM signal (KS) | digital_in | NEXUSS3-C-5 | SPI 1 | digital_in | corroborated | |
| OEM-B-3 | Intake air temp (THA) | temp_in | NEXUSS3-C-13 | AVI 4 | analog_in | corroborated | |
| OEM-B-4 | Coolant temp (THW) | temp_in | NEXUSS3-C-11 | AVI 2 | analog_in | corroborated | |
| OEM-B-6 | Primary O2 sensor (OX1) | lambda_nb_in | NEXUSS3-C-12 | AVI 3 | analog_in | corroborated | |
| OEM-B-9 | Sensor ground (E2) | sensor_ground | NEXUSS3-C-26 | Signal ground | sensor_ground | corroborated | |
| OEM-D-9 | Vehicle speed sensor (SPD) | digital_in | NEXUSS3-C-6 | SPI 2 | digital_in | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-A-26 | SP-GND-1 | 0.85 | no route | Power ground (E01/E02) | — | |
| W2 | SP-GND-1 | NEXUSS3-A-10 | 0.85 | no route | Battery ground | — | |
| W3 | SP-GND-1 | NEXUSS3-A-11 | 0.85 | no route | Battery ground | — | |
| W4 | OEM-B-9 | SP-0V-1 | 0.5 | no route | Sensor ground (E2) | — | |
| W5 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | no route | Signal ground | — | |
| W6 | OEM-A-12 | NEXUSS3-A-1 | 0.5 | no route | Injectors 1 & 4 (No.10) | — | |
| W7 | OEM-A-11 | NEXUSS3-A-2 | 0.5 | no route | Injectors 2 & 6 (No.20) | — | |
| W8 | OEM-A-25 | NEXUSS3-A-3 | 0.5 | no route | Injectors 3 & 5 (No.30) | — | |
| W9 | OEM-B-11 | NEXUSS3-C-10 | 0.5 | no route | Throttle position sensor (VTA) | — | |
| W10 | OEM-B-4 | NEXUSS3-C-11 | 0.5 | no route | Coolant temp (THW) | — | |
| W11 | OEM-B-2 | NEXUSS3-C-5 | 0.5 | no route | Karman-vortex AFM signal (KS) | — | |
| W12 | OEM-B-6 | NEXUSS3-C-12 | 0.5 | no route | Primary O2 sensor (OX1) | — | |
| W13 | OEM-B-3 | NEXUSS3-C-13 | 0.5 | no route | Intake air temp (THA) | — | |
| W14 | OEM-D-9 | NEXUSS3-C-6 | 0.5 | no route | Vehicle speed sensor (SPD) | — |
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 (5)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | PHYS_REQUIRED_OPEN | NEXUSS3-A-18 | NEXUSS3-A-18 "+12V switched input" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | NEXUSS3-A-25 | NEXUSS3-A-25 "+12V switched input" is required but not wired. |
| warn | NO_FUEL_PUMP | fuel pump | This engine harness has no fuel-pump control path: no fuel-pump relay output is wired to the new ECU. If the stock car switches the pump outside the ECU (an airflow-meter contact or a separate module), the standalone must drive the pump relay itself — see the install notes for this car. |
| info | NET_FAMILY | OEM-B-3 ↔ NEXUSS3-C-13 | OEM-B-3 "Intake air temp (THA)" [temp_in] is wired to NEXUSS3-C-13 "AVI 4" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | NET_FAMILY | OEM-B-4 ↔ NEXUSS3-C-11 | OEM-B-4 "Coolant temp (THW)" [temp_in] is wired to NEXUSS3-C-11 "AVI 2" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
Accepted (0)
| Code | Subject | Reason | By |
|---|
Notes
Auto-mapped by auto_map() from the library pin data on 2026-10-11. Review every wire against both manuals before building. Open items: - Main-relay feed: no ecu_main_power pin on the stock or the new ECU - NEXUSS3-A 18: +12V switched input: required by Haltech Nexus S3 but no stock pin feeds it; wire by hand - NEXUSS3-A 25: +12V switched input: required by Haltech Nexus S3 but no stock pin feeds it; wire by hand - Fuel-pump control: Haltech Nexus S3 needs to drive the fuel pump, but the stock ECU has no fuel-pump output (an airflow-meter contact or a separate module runs it). Add a fuel-pump relay on a spare low-side output — see the install notes for this car. Not wired: - 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 | Toyota 7M-GTE EFI manual — "Terminals of ECU" (complete terminal list, no pin numbers) | http://shoarmateam.nl/upload/Toyota-Other/Cressida/MX83/efi%20system%20+%20WIRING/toyota-7m-manual-efi-fi%5b1%5d.pdf | — | — | — |
| 2 | forum | AllPinouts: 1989–1992 Toyota Supra ECU | https://allpinouts.org/pinouts/connectors/car/1989-1992-toyota-supra-ecu/ | — | — | — |