ECU - Electronic Control Unit Connector.
The 1994–1996 Infiniti G20 (P10 platform) uses Nissan’s ECCS (Electronic Concentrated Control System) engine management with the SR20DE 2.0L inline-four. The ECM is mounted in the engine bay and connects to the vehicle harness via a large multi-pin connector whose layout differs from the earlier 1991–1993 unit. Dual oxygen sensors — front and rear — are fitted to meet the OBD-II emissions requirements phased in for 1996. The 1995 and 1996 model years share an identical connector and pin assignment to the 1994 unit.
| Pin | name | Signal |
|---|---|---|
| 3 | Tachometer Signal | RPM |
| 23 | Throttle Position Sensor | Analog |
| 26 | Vehicle Speed Sensor | Speed |
| 33 | Throttle Position Sensor (A/T) | Analog |
| 46 | O2 Sensor Signal (Front) | Analog |
| 47 | Mass Air Flow Sensor | Analog |
| 48 | Mass Air Flow Sensor Ground | Ground |
| 50 | Sensor Ground | Ground |
| 51 | Engine Coolant Temperature Sensor | Analog |
| 52 | O2 Sensor Signal (Rear) | Analog |
| 63 | Intake Air Temperature Sensor | Analog |
| 70 | Power Supply (Aux) | Power |
| 102 | Injector # 1 | Speed |
| 104 | Injector # 3 | Speed |
| 107 | Injector # 2 | Speed |
| 109 | Injector # 4 | Speed |
| 112 | Power Ground (Electronic Concentrated Control System) | Ground |
| 118 | Power Ground (Electronic Concentrated Control System) | Ground |
Notes
The 1994–1996 (P10) ECM connector layout differs significantly from the earlier 1991–1993 unit; the two are not interchangeable. The ECCS power grounds at pins 112 and 118 must both be securely connected for correct system operation. The auxiliary power supply at pin 70 is absent on the later P11 (1999) model. Always disconnect the negative battery terminal before unplugging the ECM harness connector.
Signals
- Pin 3 — Tachometer Signal — engine speed signal from the ECM to the instrument cluster (RPM output).
- Pin 23 — Throttle Position Sensor — analogue voltage from the TPS indicating throttle plate angle.
- Pin 26 — Vehicle Speed Sensor — pulse signal used by the ECM for fuel and ignition calculations.
- Pin 33 — Throttle Position Sensor (A/T) — secondary TPS input used on automatic-transmission variants.
- Pin 46 — O2 Sensor Signal (Front) — upstream (pre-catalyst) heated oxygen sensor voltage for closed-loop fuelling.
- Pin 47 — Mass Air Flow Sensor — hot-wire MAF analogue voltage for air-mass measurement.
- Pin 48 — Mass Air Flow Sensor Ground — dedicated signal ground for the MAF sensor.
- Pin 50 — Sensor Ground — common reference ground for analogue sensors.
- Pin 51 — Engine Coolant Temperature Sensor — NTC thermistor voltage used for warm-up enrichment and cooling-fan control.
- Pin 52 — O2 Sensor Signal (Rear) — downstream (post-catalyst) oxygen sensor voltage for catalyst efficiency monitoring.
- Pin 63 — Intake Air Temperature Sensor — NTC thermistor voltage for air-density correction.
- Pin 70 — Power Supply (Aux) — auxiliary ECM power feed.
- Pin 102 — Injector #1 — fuel injector drive signal, cylinder 1.
- Pin 104 — Injector #3 — fuel injector drive signal, cylinder 3.
- Pin 107 — Injector #2 — fuel injector drive signal, cylinder 2.
- Pin 109 — Injector #4 — fuel injector drive signal, cylinder 4.
- Pin 112 — Power Ground (ECCS) — main ECM power ground for the ECCS system.
- Pin 118 — Power Ground (ECCS) — secondary ECM power ground for the ECCS system.