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Lexus SC400 1992-97 (1UZ-FE non-VVTi) → Haltech Nexus S3 HT-213000 (auto)

Lexus SC400 1992-97 (1UZ-FE non-VVTi) — Haltech — Nexus S3
Drawn by Michael Gnankou · Rev 0 · proposal · 2026-10-11

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.

Statusproposal · not yet verified: nobody has reported building and running this harness
Open errorsnone
Size of the job56 wires · 9 connectors · 0 part lines
ToolsCrimp and extraction tools for each terminal family (see Connectors) · wire strippers · multimeter · heat gun + heat-shrink
Order of work1. 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.

WireFromToGaugeColourCutLabelCrimp ACrimp BPin APin BContinuity
W1OEM-A-12SP-14V-10.85☐☐☐☐☐☐☐
W2OEM-A-13SP-14V-10.85☐☐☐☐☐☐☐
W3SP-14V-1NEXUSS3-A-180.85☐☐☐☐☐☐☐
W4SP-14V-1NEXUSS3-A-250.85☐☐☐☐☐☐☐
W5OEM-A-22SP-GND-10.85☐☐☐☐☐☐☐
W6OEM-D-13SP-GND-10.85☐☐☐☐☐☐☐
W7OEM-D-26SP-GND-10.85☐☐☐☐☐☐☐
W8SP-GND-1NEXUSS3-A-100.85☐☐☐☐☐☐☐
W9SP-GND-1NEXUSS3-A-110.85☐☐☐☐☐☐☐
W10OEM-A-18SP-0V-10.5☐☐☐☐☐☐☐
W11OEM-C-15SP-0V-10.5☐☐☐☐☐☐☐
W12OEM-C-16SP-0V-10.5☐☐☐☐☐☐☐
W13SP-0V-1NEXUSS3-C-260.5☐☐☐☐☐☐☐
W14OEM-A-11NEXUSS3-C-250.5☐☐☐☐☐☐☐
W15OEM-C-8NEXUSS3-C-10.5☐☐☐☐☐☐☐
W16SP-0V-1NEXUSS3-C-20.5☐☐☐☐☐☐☐
W17OEM-C-7NEXUSS3-C-30.5☐☐☐☐☐☐☐
W18SP-0V-1NEXUSS3-C-40.5☐☐☐☐☐☐☐
W19OEM-C-6NEXUSS3-C-50.5☐☐☐☐☐☐☐
W20OEM-C-3NEXUSS3-C-230.5☐☐☐☐☐☐☐
W21OEM-C-11NEXUSS3-C-240.5☐☐☐☐☐☐☐
W22OEM-C-5NEXUSS3-A-270.5☐☐☐☐☐☐☐
W23OEM-C-13NEXUSS3-A-280.5☐☐☐☐☐☐☐
W24OEM-D-12NEXUSS3-A-10.5☐☐☐☐☐☐☐
W25OEM-D-11NEXUSS3-A-20.5☐☐☐☐☐☐☐
W26OEM-D-24NEXUSS3-A-30.5☐☐☐☐☐☐☐
W27OEM-D-25NEXUSS3-A-40.5☐☐☐☐☐☐☐
W28OEM-A-1NEXUSS3-A-130.5☐☐☐☐☐☐☐
W29OEM-A-4NEXUSS3-C-100.5☐☐☐☐☐☐☐
W30OEM-A-5NEXUSS3-C-110.5☐☐☐☐☐☐☐
W31OEM-B-4NEXUSS3-A-260.5☐☐☐☐☐☐☐
W32OEM-B-6NEXUSS3-A-90.5☐☐☐☐☐☐☐
W33OEM-B-7NEXUSS3-A-120.5☐☐☐☐☐☐☐
W34OEM-D-19NEXUSS3-C-330.5☐☐☐☐☐☐☐
W35OEM-D-20NEXUSS3-A-140.5☐☐☐☐☐☐☐
W36OEM-D-17NEXUSS3-A-150.5☐☐☐☐☐☐☐
W37OEM-D-8NEXUSS3-A-160.5☐☐☐☐☐☐☐
W38OEM-D-7NEXUSS3-A-170.5☐☐☐☐☐☐☐
W39OEM-D-6NEXUSS3-A-50.5☐☐☐☐☐☐☐
W40OEM-D-5NEXUSS3-A-60.5☐☐☐☐☐☐☐
W41OEM-B-5NEXUSS3-A-70.5☐☐☐☐☐☐☐
W42OEM-B-8NEXUSS3-A-80.5☐☐☐☐☐☐☐
W43OEM-A-17NEXUSS3-C-120.5☐☐☐☐☐☐☐
W44OEM-A-6NEXUSS3-C-130.5☐☐☐☐☐☐☐
W45OEM-B-11NEXUSS3-C-140.5☐☐☐☐☐☐☐
W46OEM-B-24NEXUSS3-C-150.5☐☐☐☐☐☐☐
W47OEM-A-16NEXUSS3-C-160.5☐☐☐☐☐☐☐
W48OEM-A-7NEXUSS3-C-170.5☐☐☐☐☐☐☐
W49OEM-C-2NEXUSS3-C-60.5☐☐☐☐☐☐☐
W50OEM-C-10NEXUSS3-C-70.5☐☐☐☐☐☐☐
W51OEM-A-19NEXUSS3-C-80.5☐☐☐☐☐☐☐
W52OEM-A-9NEXUSS3-C-190.5☐☐☐☐☐☐☐
W53OEM-A-20NEXUSS3-C-200.5☐☐☐☐☐☐☐
W54OEM-A-14NEXUSS3-C-180.5☐☐☐☐☐☐☐
W55OEM-A-2NEXUSS3-C-270.5☐☐☐☐☐☐☐
W56OEM-B-19NEXUSS3-C-280.5☐☐☐☐☐☐☐

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 AProbe BExpectWhyReading
1NEXUSS3-A-18NEXUSS3-A-10open (OL)+12 V supply must not touch power ground
2NEXUSS3-A-18NEXUSS3-C-2open (OL)+12 V supply must not touch sensor ground
3NEXUSS3-C-25NEXUSS3-A-10open (OL)5 V sensor reference must not touch power ground
4NEXUSS3-C-25NEXUSS3-C-2open (OL)5 V sensor reference must not touch sensor ground
5NEXUSS3-C-25NEXUSS3-A-18open (OL)5 V sensor reference must not touch +12 V supply

If any reading doesn't match, stop and get help before powering up.

Revisions

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Schematic

NEXUSS3-ANEXUSS3-COEM-AOEM-BOEM-COEM-DSP-0VSP-14VSP-GND

Connectors

NEXUSS3-A

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1Injector 1—W24—0.5OEM-D-12———
10Battery ground—W8—0.85SP-GND-1———
11Battery ground—W9—0.85SP-GND-1———
12DPO 2—W33—0.5OEM-B-7———
13Ignition switch input—W28—0.5OEM-A-1———
14DPO 3—W35—0.5OEM-D-20———
15DPO 4—W36—0.5OEM-D-17———
16DPO 5—W37—0.5OEM-D-8———
17DPO 6—W38—0.5OEM-D-7———
18+12V switched input—W3—0.85SP-14V-1———
19HBO 1————————
2Injector 2—W25—0.5OEM-D-11———
20HBO 2————————
21HBO 3————————
22HBO 4————————
23CAN 1 High————————
24CAN 1 Low————————
25+12V switched input—W4—0.85SP-14V-1———
26ECR output—W31—0.5OEM-B-4———
27Ignition 1—W22—0.5OEM-C-5———
28Ignition 2—W23—0.5OEM-C-13———
29Ignition 3————————
3Injector 3—W26—0.5OEM-D-24———
30Ignition 4————————
31Ignition 5————————
32Ignition 6————————
33Ignition 7————————
34Ignition 8————————
4Injector 4—W27—0.5OEM-D-25———
5Injector 5—W39—0.5OEM-D-6———
6Injector 6—W40—0.5OEM-D-5———
7Injector 7—W41—0.5OEM-B-5———
8Injector 8—W42—0.5OEM-B-8———
9DPO 1—W32—0.5OEM-B-6———

NEXUSS3-C

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1Trigger +—W15—0.5OEM-C-8———
10AVI 1—W29—0.5OEM-A-4———
11AVI 2—W30—0.5OEM-A-5———
12AVI 3—W43—0.5OEM-A-17———
13AVI 4—W44—0.5OEM-A-6———
14AVI 5—W45—0.5OEM-B-11———
15AVI 6—W46—0.5OEM-B-24———
16AVI 7—W47—0.5OEM-A-16———
17AVI 8—W48—0.5OEM-A-7———
18AVI 9—W54—0.5OEM-A-14———
19SPI 5—W52—0.5OEM-A-9———
2Trigger -—W16—0.5SP-0V-1———
20SPI 6—W53—0.5OEM-A-20———
21CAN 2 High————————
22CAN 2 Low————————
23Knock 1—W20—0.5OEM-C-3———
24Knock 2—W21—0.5OEM-C-11———
25+5V—W14—0.5OEM-A-11———
26Signal ground—W13—0.5SP-0V-1———
27AVI 10—W55—0.5OEM-A-2———
28AVI 11—W56—0.5OEM-B-19———
29WBI 1 Heater +————————
3Home +—W17—0.5OEM-C-7———
30WBI 1 Input————————
31WBI 1 Pump————————
32WBI 1 Nernst————————
33WBI 1 Heater -—W34—0.5OEM-D-19———
34WBI 1 Cal————————
4Home -—W18—0.5SP-0V-1———
5SPI 1—W19—0.5OEM-C-6———
6SPI 2—W49—0.5OEM-C-2———
7SPI 3—W50—0.5OEM-C-10———
8SPI 4—W51—0.5OEM-A-19———
9+8V————————

OEM-A

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1Ignition switch (IGSW)—W28—0.5NEXUSS3-A-13———
11Sensor supply +5V (VC)—W14—0.5NEXUSS3-C-25———
12EFI main relay (B+)—W1—0.85SP-14V-1———
13EFI main relay (B1+)—W2—0.85SP-14V-1———
14Neutral start switch (NSW)—W54—0.5NEXUSS3-C-18———
16Intake air temperature (THA)—W47—0.5NEXUSS3-C-16———
17O2 right front (OXR1)—W43—0.5NEXUSS3-C-12———
18Sensor ground (E2)—W10—0.5SP-0V-1———
19Vehicle speed (SPD)—W51—0.5NEXUSS3-C-8———
2Starter signal (STA)—W55—0.5NEXUSS3-C-27———
20Diagnostic test 2 (TE2)—W53—0.5NEXUSS3-C-20———
22Power ground (E1)—W5—0.85SP-GND-1———
4Throttle position (VTA1)—W29—0.5NEXUSS3-C-10———
5Coolant temperature (THW)—W30—0.5NEXUSS3-C-11———
6O2 left front (OXL1)—W44—0.5NEXUSS3-C-13———
7EGR temperature sensor—W48—0.5NEXUSS3-C-17———
8Knock/shield (KS)————————
9Diagnostic test 1 (TE1)—W52—0.5NEXUSS3-C-19———

OEM-B

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
11O2 right rear (OXR2)—W45—0.5NEXUSS3-C-14———
19Stop light switch (BK)—W56—0.5NEXUSS3-C-28———
20A/T kickdown switch (KD)————————
23A/C request (AC)————————
24O2 left rear (OXL2)—W46—0.5NEXUSS3-C-15———
26Battery constant (BATT)————————
4EFI main relay control (MREL)—W31—0.5NEXUSS3-A-26———
5Check-engine lamp (W)—W41—0.5NEXUSS3-A-7———
6Fuel pump relay (FPR)—W32—0.5NEXUSS3-A-9———
7A/C clutch relay (ACMG)—W33—0.5NEXUSS3-A-12———
8Fuel pump control (FC)—W42—0.5NEXUSS3-A-8———

OEM-C

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1TPS idle switch (IDL)————————
10Igniter 2 feedback (IGF2)—W50—0.5NEXUSS3-C-7———
11Knock sensor 2 (KNK2)—W21—0.5NEXUSS3-C-24———
12Check connector VF2————————
13Ignition 2 (IGT2)—W23—0.5NEXUSS3-A-28———
15Cam sensor ground (G-)—W11—0.5SP-0V-1———
16Crank sensor - (NE-)—W12—0.5SP-0V-1———
2Igniter 1 feedback (IGF1)—W49—0.5NEXUSS3-C-6———
3Knock sensor 1 (KNK1)—W20—0.5NEXUSS3-C-23———
4Check connector VF1————————
5Ignition 1 (IGT1)—W22—0.5NEXUSS3-A-27———
6Cam sensor 2 + (G2+)—W19—0.5NEXUSS3-C-5———
7Cam sensor 1 + (G1+)—W17—0.5NEXUSS3-C-3———
8Crank sensor + (NE+)—W15—0.5NEXUSS3-C-1———

OEM-D

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
11Injector 2&8 (#20)—W25—0.5NEXUSS3-A-2———
12Injector 1&7 (#10)—W24—0.5NEXUSS3-A-1———
13Power ground (E01)—W6—0.85SP-GND-1———
17Cold start injector 1 (STJ1)—W36—0.5NEXUSS3-A-15———
19O2 heater 2 (HT2)—W34—0.5NEXUSS3-C-33———
20O2 heater 1 (HT1)—W35—0.5NEXUSS3-A-14———
21EGR solenoid————————
22Fuel pressure-up VSV (PR)————————
24Injector 3&5 (#40)—W26—0.5NEXUSS3-A-3———
25Injector 4&6 (#30)—W27—0.5NEXUSS3-A-4———
26Power ground (E02)—W7—0.85SP-GND-1———
4Cold start injector (STJ)————————
5ISC stepper coil 4 (ISC4)—W40—0.5NEXUSS3-A-6———
6ISC stepper coil 3 (ISC3)—W39—0.5NEXUSS3-A-5———
7ISC stepper coil 2 (ISC2)—W38—0.5NEXUSS3-A-17———
8ISC stepper coil 1 (ISC1)—W37—0.5NEXUSS3-A-16———

SP-0V

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W10—0.5OEM-A-18———
1——W11—0.5OEM-C-15———
1——W12—0.5OEM-C-16———
1——W13—0.5NEXUSS3-C-26———
1——W16—0.5NEXUSS3-C-2———
1——W18—0.5NEXUSS3-C-4———

SP-14V

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W1—0.85OEM-A-12———
1——W2—0.85OEM-A-13———
1——W3—0.85NEXUSS3-A-18———
1——W4—0.85NEXUSS3-A-25———

SP-GND

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W5—0.85OEM-A-22———
1——W6—0.85OEM-D-13———
1——W7—0.85OEM-D-26———
1——W8—0.85NEXUSS3-A-10———
1——W9—0.85NEXUSS3-A-11———

Pin map

OEM pointOEM functionOEM familyTarget pointTarget functionTarget familyWire colourEvidence
OEM-A-1Ignition switch (IGSW)digital_inNEXUSS3-A-13Ignition switch inputdigital_insingle_source
OEM-A-11Sensor supply +5V (VC)vrefNEXUSS3-C-25+5Vvrefsingle_source
OEM-A-12EFI main relay (B+)power_inNEXUSS3-A-18 + NEXUSS3-A-25+12V switched input + +12V switched inputpower_insingle_source
OEM-A-13EFI main relay (B1+)power_inNEXUSS3-A-18 + NEXUSS3-A-25+12V switched input + +12V switched inputpower_insingle_source
OEM-A-14Neutral start switch (NSW)digital_inNEXUSS3-C-18AVI 9analog_insingle_source
OEM-A-16Intake air temperature (THA)temp_inNEXUSS3-C-16AVI 7analog_insingle_source
OEM-A-17O2 right front (OXR1)lambda_nb_inNEXUSS3-C-12AVI 3analog_insingle_source
OEM-A-18Sensor ground (E2)sensor_groundNEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4Trigger - + Signal ground + Home -sensor_ground + trigger_insingle_source
OEM-A-19Vehicle speed (SPD)digital_inNEXUSS3-C-8SPI 4digital_insingle_source
OEM-A-2Starter signal (STA)digital_inNEXUSS3-C-27AVI 10analog_insingle_source
OEM-A-20Diagnostic test 2 (TE2)digital_inNEXUSS3-C-20SPI 6digital_insingle_source
OEM-A-22Power ground (E1)groundNEXUSS3-A-10 + NEXUSS3-A-11Battery ground + Battery groundgroundsingle_source
OEM-A-4Throttle position (VTA1)analog_inNEXUSS3-C-10AVI 1analog_insingle_source
OEM-A-5Coolant temperature (THW)temp_inNEXUSS3-C-11AVI 2analog_insingle_source
OEM-A-6O2 left front (OXL1)lambda_nb_inNEXUSS3-C-13AVI 4analog_insingle_source
OEM-A-7EGR temperature sensortemp_inNEXUSS3-C-17AVI 8analog_insingle_source
OEM-A-8Knock/shield (KS)knock_in———single_source
OEM-A-9Diagnostic test 1 (TE1)digital_inNEXUSS3-C-19SPI 5digital_insingle_source
OEM-B-11O2 right rear (OXR2)lambda_nb_inNEXUSS3-C-14AVI 5analog_insingle_source
OEM-B-19Stop light switch (BK)digital_inNEXUSS3-C-28AVI 11analog_insingle_source
OEM-B-20A/T kickdown switch (KD)digital_in———single_source
OEM-B-23A/C request (AC)digital_in———single_source
OEM-B-24O2 left rear (OXL2)lambda_nb_inNEXUSS3-C-15AVI 6analog_insingle_source
OEM-B-26Battery constant (BATT)power_in———single_source
OEM-B-4EFI main relay control (MREL)low_side_outNEXUSS3-A-26ECR outputlow_side_outsingle_source
OEM-B-5Check-engine lamp (W)low_side_outNEXUSS3-A-7Injector 7injector_outsingle_source
OEM-B-6Fuel pump relay (FPR)low_side_outNEXUSS3-A-9DPO 1low_side_outsingle_source
OEM-B-7A/C clutch relay (ACMG)low_side_outNEXUSS3-A-12DPO 2low_side_outsingle_source
OEM-B-8Fuel pump control (FC)low_side_outNEXUSS3-A-8Injector 8injector_outsingle_source
OEM-C-1TPS idle switch (IDL)digital_in———single_source
OEM-C-10Igniter 2 feedback (IGF2)digital_inNEXUSS3-C-7SPI 3digital_insingle_source
OEM-C-11Knock sensor 2 (KNK2)knock_inNEXUSS3-C-24Knock 2knock_insingle_source
OEM-C-12Check connector VF2analog_out———single_source
OEM-C-13Ignition 2 (IGT2)ignition_outNEXUSS3-A-28Ignition 2ignition_outsingle_source
OEM-C-15Cam sensor ground (G-)sensor_groundNEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4Trigger - + Signal ground + Home -sensor_ground + trigger_insingle_source
OEM-C-16Crank sensor - (NE-)sensor_groundNEXUSS3-C-2 + NEXUSS3-C-26 + NEXUSS3-C-4Trigger - + Signal ground + Home -sensor_ground + trigger_insingle_source
OEM-C-2Igniter 1 feedback (IGF1)digital_inNEXUSS3-C-6SPI 2digital_insingle_source
OEM-C-3Knock sensor 1 (KNK1)knock_inNEXUSS3-C-23Knock 1knock_insingle_source
OEM-C-4Check connector VF1analog_out———single_source
OEM-C-5Ignition 1 (IGT1)ignition_outNEXUSS3-A-27Ignition 1ignition_outsingle_source
OEM-C-6Cam sensor 2 + (G2+)trigger_inNEXUSS3-C-5SPI 1digital_insingle_source
OEM-C-7Cam sensor 1 + (G1+)trigger_inNEXUSS3-C-3Home +trigger_insingle_source
OEM-C-8Crank sensor + (NE+)trigger_inNEXUSS3-C-1Trigger +trigger_insingle_source
OEM-D-11Injector 2&8 (#20)injector_outNEXUSS3-A-2Injector 2injector_outsingle_source
OEM-D-12Injector 1&7 (#10)injector_outNEXUSS3-A-1Injector 1injector_outsingle_source
OEM-D-13Power ground (E01)groundNEXUSS3-A-10 + NEXUSS3-A-11Battery ground + Battery groundgroundsingle_source
OEM-D-17Cold start injector 1 (STJ1)low_side_outNEXUSS3-A-15DPO 4low_side_outsingle_source
OEM-D-19O2 heater 2 (HT2)low_side_outNEXUSS3-C-33WBI 1 Heater -low_side_outsingle_source
OEM-D-20O2 heater 1 (HT1)low_side_outNEXUSS3-A-14DPO 3low_side_outsingle_source
OEM-D-21EGR solenoidlow_side_out———single_source
OEM-D-22Fuel pressure-up VSV (PR)low_side_out———single_source
OEM-D-24Injector 3&5 (#40)injector_outNEXUSS3-A-3Injector 3injector_outsingle_source
OEM-D-25Injector 4&6 (#30)injector_outNEXUSS3-A-4Injector 4injector_outsingle_source
OEM-D-26Power ground (E02)groundNEXUSS3-A-10 + NEXUSS3-A-11Battery ground + Battery groundgroundsingle_source
OEM-D-4Cold start injector (STJ)low_side_out———single_source
OEM-D-5ISC stepper coil 4 (ISC4)low_side_outNEXUSS3-A-6Injector 6injector_outsingle_source
OEM-D-6ISC stepper coil 3 (ISC3)low_side_outNEXUSS3-A-5Injector 5injector_outsingle_source
OEM-D-7ISC stepper coil 2 (ISC2)low_side_outNEXUSS3-A-17DPO 6low_side_outsingle_source
OEM-D-8ISC stepper coil 1 (ISC1)low_side_outNEXUSS3-A-16DPO 5low_side_outsingle_source

Cut list

WireFromToGauge (mm²)ColourLengthSignalIdent
W1OEM-A-12SP-14V-10.85no routeEFI main relay (B+)—
W2OEM-A-13SP-14V-10.85no routeEFI main relay (B1+)—
W3SP-14V-1NEXUSS3-A-180.85no route+12V switched input—
W4SP-14V-1NEXUSS3-A-250.85no route+12V switched input—
W5OEM-A-22SP-GND-10.85no routePower ground (E1)—
W6OEM-D-13SP-GND-10.85no routePower ground (E01)—
W7OEM-D-26SP-GND-10.85no routePower ground (E02)—
W8SP-GND-1NEXUSS3-A-100.85no routeBattery ground—
W9SP-GND-1NEXUSS3-A-110.85no routeBattery ground—
W10OEM-A-18SP-0V-10.5no routeSensor ground (E2)—
W11OEM-C-15SP-0V-10.5no routeCam sensor ground (G-)—
W12OEM-C-16SP-0V-10.5no routeCrank sensor - (NE-)—
W13SP-0V-1NEXUSS3-C-260.5no routeSignal ground—
W14OEM-A-11NEXUSS3-C-250.5no routeSensor supply +5V (VC)—
W15OEM-C-8NEXUSS3-C-10.5no routeCrank sensor + (NE+)—
W16SP-0V-1NEXUSS3-C-20.5no routeTrigger -—
W17OEM-C-7NEXUSS3-C-30.5no routeCam sensor 1 + (G1+)—
W18SP-0V-1NEXUSS3-C-40.5no routeHome -—
W19OEM-C-6NEXUSS3-C-50.5no routeCam sensor 2 + (G2+)—
W20OEM-C-3NEXUSS3-C-230.5no routeKnock sensor 1 (KNK1)—
W21OEM-C-11NEXUSS3-C-240.5no routeKnock sensor 2 (KNK2)—
W22OEM-C-5NEXUSS3-A-270.5no routeIgnition 1 (IGT1)—
W23OEM-C-13NEXUSS3-A-280.5no routeIgnition 2 (IGT2)—
W24OEM-D-12NEXUSS3-A-10.5no routeInjector 1&7 (#10)—
W25OEM-D-11NEXUSS3-A-20.5no routeInjector 2&8 (#20)—
W26OEM-D-24NEXUSS3-A-30.5no routeInjector 3&5 (#40)—
W27OEM-D-25NEXUSS3-A-40.5no routeInjector 4&6 (#30)—
W28OEM-A-1NEXUSS3-A-130.5no routeIgnition switch (IGSW)—
W29OEM-A-4NEXUSS3-C-100.5no routeThrottle position (VTA1)—
W30OEM-A-5NEXUSS3-C-110.5no routeCoolant temperature (THW)—
W31OEM-B-4NEXUSS3-A-260.5no routeEFI main relay control (MREL)—
W32OEM-B-6NEXUSS3-A-90.5no routeFuel pump relay (FPR)—
W33OEM-B-7NEXUSS3-A-120.5no routeA/C clutch relay (ACMG)—
W34OEM-D-19NEXUSS3-C-330.5no routeO2 heater 2 (HT2)—
W35OEM-D-20NEXUSS3-A-140.5no routeO2 heater 1 (HT1)—
W36OEM-D-17NEXUSS3-A-150.5no routeCold start injector 1 (STJ1)—
W37OEM-D-8NEXUSS3-A-160.5no routeISC stepper coil 1 (ISC1)—
W38OEM-D-7NEXUSS3-A-170.5no routeISC stepper coil 2 (ISC2)—
W39OEM-D-6NEXUSS3-A-50.5no routeISC stepper coil 3 (ISC3)—
W40OEM-D-5NEXUSS3-A-60.5no routeISC stepper coil 4 (ISC4)—
W41OEM-B-5NEXUSS3-A-70.5no routeCheck-engine lamp (W)—
W42OEM-B-8NEXUSS3-A-80.5no routeFuel pump control (FC)—
W43OEM-A-17NEXUSS3-C-120.5no routeO2 right front (OXR1)—
W44OEM-A-6NEXUSS3-C-130.5no routeO2 left front (OXL1)—
W45OEM-B-11NEXUSS3-C-140.5no routeO2 right rear (OXR2)—
W46OEM-B-24NEXUSS3-C-150.5no routeO2 left rear (OXL2)—
W47OEM-A-16NEXUSS3-C-160.5no routeIntake air temperature (THA)—
W48OEM-A-7NEXUSS3-C-170.5no routeEGR temperature sensor—
W49OEM-C-2NEXUSS3-C-60.5no routeIgniter 1 feedback (IGF1)—
W50OEM-C-10NEXUSS3-C-70.5no routeIgniter 2 feedback (IGF2)—
W51OEM-A-19NEXUSS3-C-80.5no routeVehicle speed (SPD)—
W52OEM-A-9NEXUSS3-C-190.5no routeDiagnostic test 1 (TE1)—
W53OEM-A-20NEXUSS3-C-200.5no routeDiagnostic test 2 (TE2)—
W54OEM-A-14NEXUSS3-C-180.5no routeNeutral start switch (NSW)—
W55OEM-A-2NEXUSS3-C-270.5no routeStarter signal (STA)—
W56OEM-B-19NEXUSS3-C-280.5no routeStop light switch (BK)—

Bill of materials

CategoryPart numberManufacturerDescriptionQtyUnit

ECU setup sheet

RoleEngine refEngine signalSensorECU pointECU functionECU classSetup flag
No configured channels.

Findings

Open (14)

SeverityCodeSubjectMessage
warnLOAD_UNKNOWNNEXUSS3-A-26NEXUSS3-A-26 "ECR output" drives OEM-B-4 EFI main relay control (MREL) (load 0.2 A) but its current rating is unknown. Check the ECU manual.
warnNET_FAMILYOEM-A-14 ↔ NEXUSS3-C-18OEM-A-14 "Neutral start switch (NSW)" [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.
warnNET_FAMILYOEM-A-2 ↔ NEXUSS3-C-27OEM-A-2 "Starter signal (STA)" [digital_in] is wired to NEXUSS3-C-27 "AVI 10" [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.
warnNET_FAMILYOEM-B-19 ↔ NEXUSS3-C-28OEM-B-19 "Stop light switch (BK)" [digital_in] is wired to NEXUSS3-C-28 "AVI 11" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value.
warnNET_FAMILYOEM-C-6 ↔ NEXUSS3-C-5OEM-C-6 "Cam sensor 2 + (G2+)" [trigger_in] is wired to NEXUSS3-C-5 "SPI 1" [digital_in]. Hall-type cam/speed signals can use a digital input if it handles the frequency; VR signals cannot.
infoNET_FAMILYOEM-A-16 ↔ NEXUSS3-C-16OEM-A-16 "Intake air temperature (THA)" [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.
infoNET_FAMILYOEM-A-5 ↔ NEXUSS3-C-11OEM-A-5 "Coolant temperature (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.
infoNET_FAMILYOEM-A-7 ↔ NEXUSS3-C-17OEM-A-7 "EGR temperature sensor" [temp_in] is wired to NEXUSS3-C-17 "AVI 8" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one.
infoNET_FAMILYOEM-B-5 ↔ NEXUSS3-A-7OEM-B-5 "Check-engine lamp (W)" [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.
infoNET_FAMILYOEM-B-8 ↔ NEXUSS3-A-8OEM-B-8 "Fuel pump control (FC)" [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.
infoNET_FAMILYOEM-C-16 ↔ NEXUSS3-C-2OEM-C-16 "Crank sensor - (NE-)" [sensor_ground] is wired to NEXUSS3-C-2 "Trigger -" [trigger_in]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs.
infoNET_FAMILYOEM-D-5 ↔ NEXUSS3-A-6OEM-D-5 "ISC stepper coil 4 (ISC4)" [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.
infoNET_FAMILYOEM-D-6 ↔ NEXUSS3-A-5OEM-D-6 "ISC stepper coil 3 (ISC3)" [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.
infoUNMAPPEDOEM9 optional OEM pins are not mapped: OEM-A-8 Knock/shield (KS); OEM-B-20 A/T kickdown switch (KD); OEM-B-23 A/C request (AC); OEM-C-1 TPS idle switch (IDL); OEM-C-12 Check connector VF2; OEM-C-4 Check connector VF1; OEM-D-21 EGR solenoid; OEM-D-22 Fuel pressure-up VSV (PR); OEM-D-4 Cold start injector (STJ)

Accepted (1)

CodeSubjectReasonBy
REQUIRED_UNMAPPEDOEM-B-26Battery-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 2026-10-11. Review every wire against both manuals before building. Not wired: - OEM-B 26: Battery constant (BATT): Haltech Nexus S3 has no battery-constant input; not needed - OEM-A 8: Knock/shield (KS): no free knock input on Haltech Nexus S3 - OEM-D 21: EGR solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on Haltech Nexus S3 - OEM-D 22: Fuel pressure-up VSV (PR): no free low_side/relay_control/heater_low_side/ls_hs/injector on Haltech Nexus S3 - OEM-D 4: Cold start injector (STJ): no free low_side/relay_control/heater_low_side/ls_hs/injector on Haltech Nexus S3 - OEM-B 20: A/T kickdown switch (KD): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-B 23: A/C request (AC): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-C 1: TPS idle switch (IDL): no free switch_in/frequency_in/analog_0_5 on Haltech Nexus S3 - OEM-C 4: Check connector VF1: no free analog_out on Haltech Nexus S3 - OEM-C 12: Check connector VF2: no free analog_out on Haltech Nexus S3

Sources

ReliabilityKindTitleURLArchiveCapturedSHA-256
4vendor_docHaltech: Nexus S3 Plug 'n' Play adapter QSG (Subaru WRX/STI ADM, HT-186300) — ECU Connector A & C pinouthttps://www.haltech.com/product/ht-186300-nexus-s3-plug-n-play-adapter-harness/archive2026-10-053cab7cd337c2
4vendor_docHaltech: Nexus S3/S2 ECU Overview (QSG) — specificationshttps://store.haltech.com/product/ht-213000-nexus-s3-ecu-only/archive2026-10-05388299668207
2community_copyLextreme: Adaptronic install for 1UZ-FE (Lexus LS400/SC400) — 4-plug A/B/C/D ECU pin table (1992 LS400)https://www.lextreme.com/installation-of-an-adaptronic-ecu-for-a-lexus-ls400-sc400-1uzfe-engine/———