ECU - Electronic Control Unit Connector.
The Nissan 180SX (S13 chassis, 1989–1993) fitted with the CA18DET turbocharged 1.8-litre DOHC inline-four engine uses a 76-pin ECU connector as part of the ECCS (Electronic Concentrated Control System) — Nissan’s proprietary sequential multi-point fuel injection and electronic ignition management system. The ECU governs injector firing, ignition timing, boost control, and sensor signal processing through a single multi-pin header. This connector arrangement is specific to the CA18DET S13 platform and is documented in the S13 factory service manual under section EF & EC (Engine Fuel & Emission Control System).
Connector A
| Pin | name | Signal |
|---|---|---|
| 7 | Tachometer Signal | RPM |
| 26 | Mass Air Flow Sensor Ground | Ground |
| 27 | Mass Air Flow Sensor | Analog |
| 28 | Engine Coolant Temperature Sensor | Analog |
| 29 | O2 Sensor Signal | Analog |
| 30 | Sensor Ground | Ground |
| 38 | Throttle Position Sensor | Analog |
| 50 | Power Ground (Engine Control Module) | Ground |
| 53 | Vehicle Speed Sensor | Speed |
| 101 | Injector # 1 | Speed |
| 103 | Injector # 3 | Speed |
| 110 | Injector # 2 | Speed |
| 112 | Injector # 4 | Speed |
| 116 | Power Ground (Engine Control Module) | Ground |
Notes
The ECU connector on the S13 CA18DET is a 76-pin multi-pin header. Only a subset of pins is documented in the table above; remaining positions are either unpopulated or carry signals not listed in available documentation. The ECCS system communicates with the Nissan CONSULT diagnostic interface via a dedicated data link connector; self-diagnostic mode is accessible without CONSULT using the ECU’s LED output and ignition-key sequence. Pin numbers above 100 belong to the injector driver sub-harness section of the connector.
Signals
- Tachometer Signal — engine speed output (RPM pulse) sent to the instrument cluster tachometer
- Mass Air Flow Sensor Ground — dedicated ground return for the MAF sensor circuit
- Mass Air Flow Sensor — analogue voltage signal from the hot-wire mass air flow meter
- Engine Coolant Temperature Sensor — analogue voltage signal proportional to coolant temperature; used for fuel enrichment and fan control
- O2 Sensor Signal — analogue voltage from the exhaust oxygen sensor; used for closed-loop fuel trim
- Sensor Ground — common ground reference for analogue sensor inputs
- Throttle Position Sensor — analogue voltage indicating throttle plate angle; used for load calculation and acceleration enrichment
- Power Ground (Engine Control Module) — chassis/battery ground for the ECU power supply (pins 50 and 116)
- Vehicle Speed Sensor — pulse signal from the gearbox speed sensor used for speed-dependent corrections
- Injector #1, #2, #3, #4 — saturated-type injector drive signals; the ECU switches each injector to ground to fire sequentially