MX-5 Miata NB1 1999-00 (BP-4W) → Haltech Nexus S3 HT-213000 (auto)
MX-5 Miata NB1 1999-00 (BP-4W) — Haltech — Nexus S3
Drawn by Michael Gnankou · Rev 0 · proposal · 2026-10-04
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-3-W | — | — | — |
| 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-1-S | — | — | — |
| 13 | Ignition switch input | — | — | — | — | — | — | — | — |
| 14 | DPO 3 | — | W27 | — | 0.5 | OEM-3-N | — | — | — |
| 15 | DPO 4 | — | W29 | — | 0.5 | OEM-3-V | — | — | — |
| 16 | DPO 5 | — | W30 | — | 0.5 | OEM-3-O | — | — | — |
| 17 | DPO 6 | — | W31 | — | 0.5 | OEM-1-E | — | — | — |
| 18 | +12V switched input | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 19 | HBO 1 | — | W36 | — | 0.5 | OEM-2-O | — | — | — |
| 2 | Injector 2 | — | W21 | — | 0.5 | OEM-3-X | — | — | — |
| 20 | HBO 2 | — | W37 | — | 0.5 | OEM-2-P | — | — | — |
| 21 | HBO 3 | — | W38 | — | 0.5 | OEM-3-L | — | — | — |
| 22 | HBO 4 | — | W39 | — | 0.5 | OEM-3-Q | — | — | — |
| 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-1-I | — | — | — |
| 27 | Ignition 1 | — | W18 | — | 0.5 | OEM-3-G | — | — | — |
| 28 | Ignition 2 | — | W19 | — | 0.5 | OEM-3-H | — | — | — |
| 29 | Ignition 3 | — | — | — | — | — | — | — | — |
| 3 | Injector 3 | — | W22 | — | 0.5 | OEM-3-Y | — | — | — |
| 30 | Ignition 4 | — | — | — | — | — | — | — | — |
| 31 | Ignition 5 | — | — | — | — | — | — | — | — |
| 32 | Ignition 6 | — | — | — | — | — | — | — | — |
| 33 | Ignition 7 | — | — | — | — | — | — | — | — |
| 34 | Ignition 8 | — | — | — | — | — | — | — | — |
| 4 | Injector 4 | — | W23 | — | 0.5 | OEM-3-Z | — | — | — |
| 5 | Injector 5 | — | W32 | — | 0.5 | OEM-1-O | — | — | — |
| 6 | Injector 6 | — | W33 | — | 0.5 | OEM-1-Q | — | — | — |
| 7 | Injector 7 | — | W34 | — | 0.5 | OEM-2-M | — | — | — |
| 8 | Injector 8 | — | W35 | — | 0.5 | OEM-2-N | — | — | — |
| 9 | DPO 1 | — | W25 | — | 0.5 | OEM-1-R | — | — | — |
NEXUSS3-C
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Trigger + | — | W13 | — | 0.5 | OEM-2-J | — | — | — |
| 10 | AVI 1 | — | W40 | — | 0.5 | OEM-2-L | — | — | — |
| 11 | AVI 2 | — | W41 | — | 0.5 | OEM-3-E | — | — | — |
| 12 | AVI 3 | — | W42 | — | 0.5 | OEM-2-C | — | — | — |
| 13 | AVI 4 | — | W43 | — | 0.5 | OEM-3-J | — | — | — |
| 14 | AVI 5 | — | W44 | — | 0.5 | OEM-2-E | — | — | — |
| 15 | AVI 6 | — | W45 | — | 0.5 | OEM-2-B | — | — | — |
| 16 | AVI 7 | — | W46 | — | 0.5 | OEM-2-A | — | — | — |
| 17 | AVI 8 | — | W47 | — | 0.5 | OEM-3-K | — | — | — |
| 18 | AVI 9 | — | W48 | — | 0.5 | OEM-3-S | — | — | — |
| 19 | SPI 5 | — | W53 | — | 0.5 | OEM-1-V | — | — | — |
| 2 | Trigger - | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| 20 | SPI 6 | — | W54 | — | 0.5 | OEM-3-I | — | — | — |
| 21 | CAN 2 High | — | — | — | — | — | — | — | — |
| 22 | CAN 2 Low | — | — | — | — | — | — | — | — |
| 23 | Knock 1 | — | W17 | — | 0.5 | OEM-2-F | — | — | — |
| 24 | Knock 2 | — | — | — | — | — | — | — | — |
| 25 | +5V | — | W12 | — | 0.5 | OEM-2-I | — | — | — |
| 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-2-H | — | — | — |
| 30 | WBI 1 Input | — | — | — | — | — | — | — | — |
| 31 | WBI 1 Pump | — | — | — | — | — | — | — | — |
| 32 | WBI 1 Nernst | — | — | — | — | — | — | — | — |
| 33 | WBI 1 Heater - | — | W28 | — | 0.5 | OEM-1-U | — | — | — |
| 34 | WBI 1 Cal | — | — | — | — | — | — | — | — |
| 4 | Home - | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 5 | SPI 1 | — | W49 | — | 0.5 | OEM-2-D | — | — | — |
| 6 | SPI 2 | — | W50 | — | 0.5 | OEM-1-F | — | — | — |
| 7 | SPI 3 | — | W51 | — | 0.5 | OEM-1-G | — | — | — |
| 8 | SPI 4 | — | W52 | — | 0.5 | OEM-1-P | — | — | — |
| 9 | +8V | — | — | — | — | — | — | — | — |
OEM-1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Constant +12V | — | — | — | — | — | — | — | — |
| B | ECU power +14V (main relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| E | Malfunction indicator lamp (MIL) | — | W31 | — | 0.5 | NEXUSS3-A-17 | — | — | — |
| F | Brake switch | — | W50 | — | 0.5 | NEXUSS3-C-6 | — | — | — |
| G | Power steering pressure switch | — | W51 | — | 0.5 | NEXUSS3-C-7 | — | — | — |
| I | Condenser fan relay | — | W24 | — | 0.5 | NEXUSS3-A-26 | — | — | — |
| O | Alternator control | — | W32 | — | 0.5 | NEXUSS3-A-5 | — | — | — |
| P | A/C request | — | W52 | — | 0.5 | NEXUSS3-C-8 | — | — | — |
| Q | Charge lamp | — | W33 | — | 0.5 | NEXUSS3-A-6 | — | — | — |
| R | Cooling fan relay | — | W25 | — | 0.5 | NEXUSS3-A-9 | — | — | — |
| S | A/C clutch relay | — | W26 | — | 0.5 | NEXUSS3-A-12 | — | — | — |
| U | Front O2 heater | — | W28 | — | 0.5 | NEXUSS3-C-33 | — | — | — |
| V | Neutral switch | — | W53 | — | 0.5 | NEXUSS3-C-19 | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Fuel tank pressure | — | W46 | — | 0.5 | NEXUSS3-C-16 | — | — | — |
| B | Intake air temperature (IAT) | — | W45 | — | 0.5 | NEXUSS3-C-15 | — | — | — |
| C | Front O2 signal | — | W42 | — | 0.5 | NEXUSS3-C-12 | — | — | — |
| D | Vehicle speed | — | W49 | — | 0.5 | NEXUSS3-C-5 | — | — | — |
| E | Coolant temperature (ECT) | — | W44 | — | 0.5 | NEXUSS3-C-14 | — | — | — |
| F | Knock sensor | — | W17 | — | 0.5 | NEXUSS3-C-23 | — | — | — |
| H | Cam position (CMP) | — | W15 | — | 0.5 | NEXUSS3-C-3 | — | — | — |
| I | +5V sensor supply | — | W12 | — | 0.5 | NEXUSS3-C-25 | — | — | — |
| J | Crank position (CKP) | — | W13 | — | 0.5 | NEXUSS3-C-1 | — | — | — |
| K | Tachometer output | — | — | — | — | — | — | — | — |
| L | Mass air flow (MAF) | — | W40 | — | 0.5 | NEXUSS3-C-10 | — | — | — |
| M | EGR valve | — | W34 | — | 0.5 | NEXUSS3-A-7 | — | — | — |
| N | EGR valve | — | W35 | — | 0.5 | NEXUSS3-A-8 | — | — | — |
| O | EGR valve | — | W36 | — | 0.5 | NEXUSS3-A-19 | — | — | — |
| P | EGR valve | — | 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 | — | — | — |
| C | Power ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| E | Throttle position (TPS) | — | W41 | — | 0.5 | NEXUSS3-C-11 | — | — | — |
| F | Signal ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| G | Ignition 1 (coils 1+4, wasted spark) | — | W18 | — | 0.5 | NEXUSS3-A-27 | — | — | — |
| H | Ignition 2 (coils 2+3, wasted spark) | — | W19 | — | 0.5 | NEXUSS3-A-28 | — | — | — |
| I | Clutch switch | — | W54 | — | 0.5 | NEXUSS3-C-20 | — | — | — |
| J | Rear O2 signal | — | W43 | — | 0.5 | NEXUSS3-C-13 | — | — | — |
| K | Fuel level | — | W47 | — | 0.5 | NEXUSS3-C-17 | — | — | — |
| L | Evap purge solenoid | — | W38 | — | 0.5 | NEXUSS3-A-21 | — | — | — |
| M | ISC valve +14V feed | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| N | Fuel pump relay | — | W27 | — | 0.5 | NEXUSS3-A-14 | — | — | — |
| O | ISC valve low side | — | W30 | — | 0.5 | NEXUSS3-A-16 | — | — | — |
| Q | VICS solenoid (intake butterflies) | — | W39 | — | 0.5 | NEXUSS3-A-22 | — | — | — |
| S | EGR boost sensor | — | W48 | — | 0.5 | NEXUSS3-C-18 | — | — | — |
| T | EGR boost solenoid | — | — | — | — | — | — | — | — |
| U | Canister drain cut valve (CDCV) | — | — | — | — | — | — | — | — |
| V | Rear O2 heater | — | W29 | — | 0.5 | NEXUSS3-A-15 | — | — | — |
| W | Injector 1 | — | W20 | — | 0.5 | NEXUSS3-A-1 | — | — | — |
| X | Injector 2 | — | W21 | — | 0.5 | NEXUSS3-A-2 | — | — | — |
| Y | Injector 3 | — | W22 | — | 0.5 | NEXUSS3-A-3 | — | — | — |
| Z | Injector 4 | — | W23 | — | 0.5 | NEXUSS3-A-4 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W10 | — | 0.5 | OEM-3-F | — | — | — |
| 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-1-B | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-3-M | — | — | — |
| 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-3-C | — | — | — |
| 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-1-A | Constant +12V | power_in | — | — | — | single_source | |
| OEM-1-B | ECU power +14V (main relay) | power_in | NEXUSS3-A-18 + NEXUSS3-A-25 | +12V switched input + +12V switched input | power_in | single_source | |
| OEM-1-E | Malfunction indicator lamp (MIL) | low_side_out | NEXUSS3-A-17 | DPO 6 | low_side_out | single_source | |
| OEM-1-F | Brake switch | digital_in | NEXUSS3-C-6 | SPI 2 | digital_in | single_source | |
| OEM-1-G | Power steering pressure switch | digital_in | NEXUSS3-C-7 | SPI 3 | digital_in | single_source | |
| OEM-1-I | Condenser fan relay | low_side_out | NEXUSS3-A-26 | ECR output | low_side_out | single_source | |
| OEM-1-O | Alternator control | low_side_out | NEXUSS3-A-5 | Injector 5 | injector_out | single_source | |
| OEM-1-P | A/C request | digital_in | NEXUSS3-C-8 | SPI 4 | digital_in | single_source | |
| OEM-1-Q | Charge lamp | low_side_out | NEXUSS3-A-6 | Injector 6 | injector_out | single_source | |
| OEM-1-R | Cooling fan relay | low_side_out | NEXUSS3-A-9 | DPO 1 | low_side_out | single_source | |
| OEM-1-S | A/C clutch relay | low_side_out | NEXUSS3-A-12 | DPO 2 | low_side_out | single_source | |
| OEM-1-U | Front O2 heater | low_side_out | NEXUSS3-C-33 | WBI 1 Heater - | low_side_out | single_source | |
| OEM-1-V | Neutral switch | digital_in | NEXUSS3-C-19 | SPI 5 | digital_in | single_source | |
| OEM-2-A | Fuel tank pressure | analog_in | NEXUSS3-C-16 | AVI 7 | analog_in | single_source | |
| OEM-2-B | Intake air temperature (IAT) | temp_in | NEXUSS3-C-15 | AVI 6 | analog_in | single_source | |
| OEM-2-C | Front O2 signal | lambda_nb_in | NEXUSS3-C-12 | AVI 3 | analog_in | single_source | |
| OEM-2-D | Vehicle speed | digital_in | NEXUSS3-C-5 | SPI 1 | digital_in | single_source | |
| OEM-2-E | Coolant temperature (ECT) | temp_in | NEXUSS3-C-14 | AVI 5 | analog_in | single_source | |
| OEM-2-F | Knock sensor | knock_in | NEXUSS3-C-23 | Knock 1 | knock_in | single_source | |
| OEM-2-H | Cam position (CMP) | trigger_in | NEXUSS3-C-3 | Home + | trigger_in | single_source | |
| OEM-2-I | +5V sensor supply | vref | NEXUSS3-C-25 | +5V | vref | single_source | |
| OEM-2-J | Crank position (CKP) | trigger_in | NEXUSS3-C-1 | Trigger + | trigger_in | single_source | |
| OEM-2-K | Tachometer output | tacho_out | — | — | — | single_source | |
| OEM-2-L | Mass air flow (MAF) | analog_in | NEXUSS3-C-10 | AVI 1 | analog_in | single_source | |
| OEM-2-M | EGR valve | low_side_out | NEXUSS3-A-7 | Injector 7 | injector_out | single_source | |
| OEM-2-N | EGR valve | low_side_out | NEXUSS3-A-8 | Injector 8 | injector_out | single_source | |
| OEM-2-O | EGR valve | low_side_out | NEXUSS3-A-19 | HBO 1 | hbridge_out | single_source | |
| OEM-2-P | EGR valve | 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-C | Power ground | ground | NEXUSS3-A-10 + NEXUSS3-A-11 | Battery ground + Battery ground | ground | single_source | |
| OEM-3-E | Throttle position (TPS) | analog_in | NEXUSS3-C-11 | AVI 2 | analog_in | single_source | |
| OEM-3-F | Signal ground | sensor_ground | NEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4 | Trigger - + Signal ground + Home - | sensor_ground + trigger_in | single_source | |
| OEM-3-G | Ignition 1 (coils 1+4, wasted spark) | ignition_out | NEXUSS3-A-27 | Ignition 1 | ignition_out | single_source | |
| OEM-3-H | Ignition 2 (coils 2+3, wasted spark) | ignition_out | NEXUSS3-A-28 | Ignition 2 | ignition_out | single_source | |
| OEM-3-I | Clutch switch | digital_in | NEXUSS3-C-20 | SPI 6 | digital_in | single_source | |
| OEM-3-J | Rear O2 signal | lambda_nb_in | NEXUSS3-C-13 | AVI 4 | analog_in | single_source | |
| OEM-3-K | Fuel level | analog_in | NEXUSS3-C-17 | AVI 8 | analog_in | single_source | |
| OEM-3-L | Evap purge solenoid | low_side_out | NEXUSS3-A-21 | HBO 3 | hbridge_out | single_source | |
| OEM-3-M | ISC valve +14V feed | power_in | NEXUSS3-A-18 + NEXUSS3-A-25 | +12V switched input + +12V switched input | power_in | single_source | |
| OEM-3-N | Fuel pump relay | low_side_out | NEXUSS3-A-14 | DPO 3 | low_side_out | single_source | |
| OEM-3-O | ISC valve low side | low_side_out | NEXUSS3-A-16 | DPO 5 | low_side_out | single_source | |
| OEM-3-Q | VICS solenoid (intake butterflies) | low_side_out | NEXUSS3-A-22 | HBO 4 | hbridge_out | single_source | |
| OEM-3-S | EGR boost sensor | analog_in | NEXUSS3-C-18 | AVI 9 | analog_in | single_source | |
| OEM-3-T | EGR boost solenoid | low_side_out | — | — | — | single_source | |
| OEM-3-U | Canister drain cut valve (CDCV) | low_side_out | — | — | — | single_source | |
| OEM-3-V | Rear O2 heater | low_side_out | NEXUSS3-A-15 | DPO 4 | low_side_out | single_source | |
| OEM-3-W | Injector 1 | injector_out | NEXUSS3-A-1 | Injector 1 | injector_out | single_source | |
| OEM-3-X | Injector 2 | injector_out | NEXUSS3-A-2 | Injector 2 | injector_out | single_source | |
| OEM-3-Y | Injector 3 | injector_out | NEXUSS3-A-3 | Injector 3 | injector_out | single_source | |
| OEM-3-Z | Injector 4 | injector_out | NEXUSS3-A-4 | Injector 4 | injector_out | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-1-B | SP-14V-1 | 0.85 | no route | ECU power +14V (main relay) | — | |
| W2 | OEM-3-M | SP-14V-1 | 0.85 | no route | ISC valve +14V feed | — | |
| 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-3-C | 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-3-F | SP-0V-1 | 0.5 | no route | Signal ground | — | |
| W11 | SP-0V-1 | NEXUSS3-C-26 | 0.5 | no route | Signal ground | — | |
| W12 | OEM-2-I | NEXUSS3-C-25 | 0.5 | no route | +5V sensor supply | — | |
| W13 | OEM-2-J | NEXUSS3-C-1 | 0.5 | no route | Crank position (CKP) | — | |
| W14 | SP-0V-1 | NEXUSS3-C-2 | 0.5 | no route | Trigger - | — | |
| W15 | OEM-2-H | NEXUSS3-C-3 | 0.5 | no route | Cam position (CMP) | — | |
| W16 | SP-0V-1 | NEXUSS3-C-4 | 0.5 | no route | Home - | — | |
| W17 | OEM-2-F | NEXUSS3-C-23 | 0.5 | no route | Knock sensor | — | |
| W18 | OEM-3-G | NEXUSS3-A-27 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W19 | OEM-3-H | NEXUSS3-A-28 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W20 | OEM-3-W | NEXUSS3-A-1 | 0.5 | no route | Injector 1 | — | |
| W21 | OEM-3-X | NEXUSS3-A-2 | 0.5 | no route | Injector 2 | — | |
| W22 | OEM-3-Y | NEXUSS3-A-3 | 0.5 | no route | Injector 3 | — | |
| W23 | OEM-3-Z | NEXUSS3-A-4 | 0.5 | no route | Injector 4 | — | |
| W24 | OEM-1-I | NEXUSS3-A-26 | 0.5 | no route | Condenser fan relay | — | |
| W25 | OEM-1-R | NEXUSS3-A-9 | 0.5 | no route | Cooling fan relay | — | |
| W26 | OEM-1-S | NEXUSS3-A-12 | 0.5 | no route | A/C clutch relay | — | |
| W27 | OEM-3-N | NEXUSS3-A-14 | 0.5 | no route | Fuel pump relay | — | |
| W28 | OEM-1-U | NEXUSS3-C-33 | 0.5 | no route | Front O2 heater | — | |
| W29 | OEM-3-V | NEXUSS3-A-15 | 0.5 | no route | Rear O2 heater | — | |
| W30 | OEM-3-O | NEXUSS3-A-16 | 0.5 | no route | ISC valve low side | — | |
| W31 | OEM-1-E | NEXUSS3-A-17 | 0.5 | no route | Malfunction indicator lamp (MIL) | — | |
| W32 | OEM-1-O | NEXUSS3-A-5 | 0.5 | no route | Alternator control | — | |
| W33 | OEM-1-Q | NEXUSS3-A-6 | 0.5 | no route | Charge lamp | — | |
| W34 | OEM-2-M | NEXUSS3-A-7 | 0.5 | no route | EGR valve | — | |
| W35 | OEM-2-N | NEXUSS3-A-8 | 0.5 | no route | EGR valve | — | |
| W36 | OEM-2-O | NEXUSS3-A-19 | 0.5 | no route | EGR valve | — | |
| W37 | OEM-2-P | NEXUSS3-A-20 | 0.5 | no route | EGR valve | — | |
| W38 | OEM-3-L | NEXUSS3-A-21 | 0.5 | no route | Evap purge solenoid | — | |
| W39 | OEM-3-Q | NEXUSS3-A-22 | 0.5 | no route | VICS solenoid (intake butterflies) | — | |
| W40 | OEM-2-L | NEXUSS3-C-10 | 0.5 | no route | Mass air flow (MAF) | — | |
| W41 | OEM-3-E | NEXUSS3-C-11 | 0.5 | no route | Throttle position (TPS) | — | |
| W42 | OEM-2-C | NEXUSS3-C-12 | 0.5 | no route | Front O2 signal | — | |
| W43 | OEM-3-J | NEXUSS3-C-13 | 0.5 | no route | Rear O2 signal | — | |
| W44 | OEM-2-E | NEXUSS3-C-14 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W45 | OEM-2-B | NEXUSS3-C-15 | 0.5 | no route | Intake air temperature (IAT) | — | |
| W46 | OEM-2-A | NEXUSS3-C-16 | 0.5 | no route | Fuel tank pressure | — | |
| W47 | OEM-3-K | NEXUSS3-C-17 | 0.5 | no route | Fuel level | — | |
| W48 | OEM-3-S | NEXUSS3-C-18 | 0.5 | no route | EGR boost sensor | — | |
| W49 | OEM-2-D | NEXUSS3-C-5 | 0.5 | no route | Vehicle speed | — | |
| W50 | OEM-1-F | NEXUSS3-C-6 | 0.5 | no route | Brake switch | — | |
| W51 | OEM-1-G | NEXUSS3-C-7 | 0.5 | no route | Power steering pressure switch | — | |
| W52 | OEM-1-P | NEXUSS3-C-8 | 0.5 | no route | A/C request | — | |
| W53 | OEM-1-V | NEXUSS3-C-19 | 0.5 | no route | Neutral switch | — | |
| W54 | OEM-3-I | NEXUSS3-C-20 | 0.5 | no route | Clutch 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 (13)
| Severity | Code | Subject | Message |
|---|---|---|---|
| warn | LOAD_UNKNOWN | NEXUSS3-A-26 | NEXUSS3-A-26 "ECR output" drives OEM-1-I Condenser fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | NET_FAMILY | OEM-2-O ↔ NEXUSS3-A-19 | OEM-2-O "EGR valve" [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-P ↔ NEXUSS3-A-20 | OEM-2-P "EGR valve" [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-L ↔ NEXUSS3-A-21 | OEM-3-L "Evap purge 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-Q ↔ NEXUSS3-A-22 | OEM-3-Q "VICS solenoid (intake butterflies)" [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. |
| 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-1-O ↔ NEXUSS3-A-5 | OEM-1-O "Alternator control" [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-1-Q ↔ NEXUSS3-A-6 | OEM-1-Q "Charge lamp" [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-B ↔ NEXUSS3-C-15 | OEM-2-B "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-2-E ↔ NEXUSS3-C-14 | OEM-2-E "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-M ↔ NEXUSS3-A-7 | OEM-2-M "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-N ↔ NEXUSS3-A-8 | OEM-2-N "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 | UNMAPPED | OEM | 3 optional OEM pins are not mapped: OEM-2-K Tachometer output; OEM-3-T EGR boost solenoid; OEM-3-U Canister drain cut valve (CDCV) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-1-A | 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 2026-10-04. Review every wire against both manuals before building. Not wired: - OEM-1 A: Constant +12V: Haltech Nexus S3 has no battery-constant input; not needed - OEM-3 T: EGR boost solenoid: no free low_side/ls_hs/injector/hbridge on Haltech Nexus S3 - OEM-3 U: Canister drain cut valve (CDCV): no free low_side/ls_hs/injector/hbridge on Haltech Nexus S3 - OEM-2 K: 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 |
|---|---|---|---|
| 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/ |
| 4 | vendor_doc | Haltech: Nexus S3/S2 ECU Overview (QSG) — specifications | https://store.haltech.com/product/ht-213000-nexus-s3-ecu-only/ |
| 4 | vendor_doc | Link G4X MX5NB1X install manual (NB1 1999-00) | https://linkecu.com/documentation/MX5XNB1.pdf |