ECU - Electronic Control Unit Connector.
The 1991–1993 Infiniti G20 is the North American luxury variant of the Nissan Primera P10, powered by the SR20DE 2.0 L inline-four engine. Engine management is handled by Nissan’s ECCS (Electronic Concentrated Control System), a port fuel-injection system with an ECM that communicates with sensors for air mass, coolant temperature, throttle position, intake air temperature, exhaust oxygen content, and vehicle speed. The ECM mounts in the passenger compartment and connects to the engine harness via a large multi-row connector carrying both signal and power circuits. The P10 platform was sold from the 1991 through 1993 model years in North America before being replaced by the P11-based 1994–1996 G20, which uses a different connector layout.
| Pin | name | Signal |
|---|---|---|
| 2 | Tachometer Signal | RPM |
| 16 | Mass Air Flow Sensor | Analog |
| 17 | Mass Air Flow Sensor Ground | Ground |
| 18 | Engine Coolant Temperature Sensor | Analog |
| 19 | O2 Sensor Signal | Analog |
| 20 | Throttle Position Sensor | Analog |
| 21 | Sensor Ground | Ground |
| 26 | Air Temperature Sensor | Analog |
| 32 | Vehicle Speed Sensor | Speed |
| 48 | Power Ground (Electronic Concentrated Control System) | Ground |
| 101 | Injector # 1 | Speed |
| 103 | Injector # 3 | Speed |
| 110 | Injector # 2 | Speed |
| 112 | Injector # 4 | Speed |
| 116 | Power Ground (Electronic Concentrated Control System) | Ground |
Notes
The P10 ECM connector is a large multi-row harness connector; disconnect the negative battery terminal before unplugging it. Pin numbering follows Nissan ECCS convention and differs from the P11 connector used on 1994–1996 and 1999–2002 G20 models. The two ECCS power grounds (pins 48 and 116) must both remain securely earthed for correct ECM operation. The 1993 model year uses the same connector layout as the 1991–1992 models.
Signals
- Pin 2 (RPM) — tachometer signal output from the ECM to the instrument cluster
- Pin 16 (MAF) — analogue voltage signal from the Mass Air Flow sensor; varies with intake air volume
- Pin 17 (MAF Ground) — dedicated ground return for the Mass Air Flow sensor circuit
- Pin 18 (ECT) — analogue voltage signal from the Engine Coolant Temperature sensor; used for fuel and ignition corrections
- Pin 19 (O2) — analogue signal from the exhaust oxygen sensor; used for closed-loop fuel trim
- Pin 20 (TPS) — analogue voltage signal from the Throttle Position Sensor; indicates throttle opening angle
- Pin 21 (Sensor Ground) — common ground reference for signal-level sensors
- Pin 26 (IAT) — analogue voltage signal from the Intake Air Temperature sensor; used for fuel density correction
- Pin 32 (VSS) — Vehicle Speed Sensor pulse signal; used for speed-dependent fuel and idle control
- Pin 48 (ECCS Ground) — ECCS power ground; one of two main ECM earth connections
- Pin 101 (Injector 1) — drive signal for fuel injector on cylinder 1
- Pin 103 (Injector 3) — drive signal for fuel injector on cylinder 3
- Pin 110 (Injector 2) — drive signal for fuel injector on cylinder 2
- Pin 112 (Injector 4) — drive signal for fuel injector on cylinder 4
- Pin 116 (ECCS Ground) — second ECCS power ground; both ground pins are required for correct operation