ECU - Electronic Control Unit Connector.
The Nissan 180SX (S13 platform, 1991–1995) uses the SR20DET 2.0 litre DOHC turbocharged inline-four engine managed by Nissan’s ECCS (Electronic Concentrated Control System), which provides sequential multi-point fuel injection and electronically controlled ignition from a single ECM. The ECM communicates with sensors and actuators via a multi-pin connector array; the partial pinout below reflects the signal assignments documented for this application. Diagnostic access is provided through the Nissan CONSULT serial interface, connected via a dedicated data link connector in the cabin harness.
| Pin | name | Signal |
|---|---|---|
| 3 | Tachometer Signal | RPM |
| 13 | Power Ground (Electronic Concentrated Control System) | Ground |
| 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 |
| 39 | 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 S13 RWD SR20DET (known as the “redtop”) fitted to the 180SX uses a longitudinal rear-wheel-drive layout; its ECM wiring differs from the transverse FWD SR20DET used in the Pulsar GTi-R (N14 platform). The ECCS power grounds appear on multiple pins (13, 39, 116) to distribute current across the connector. Only a subset of ECM pins is listed here; remaining terminals are not publicly documented for this variant.
Signals
- Tachometer Signal — engine speed output from the ECM to the instrument cluster tachometer (pin 3)
- Power Ground (ECCS) — dedicated ECM power ground returns; present on pins 13, 39, and 116 to reduce resistance across the harness
- Mass Air Flow Sensor — analogue voltage from the hot-wire MAF sensor proportional to intake air mass (pin 16)
- Mass Air Flow Sensor Ground — dedicated signal ground for the MAF sensor circuit (pin 17)
- Engine Coolant Temperature Sensor — analogue voltage from the NTC coolant temperature sensor; used for fuel enrichment and ignition advance correction (pin 18)
- O2 Sensor Signal — narrow-band oxygen sensor voltage used for closed-loop fuelling correction (pin 19)
- Throttle Position Sensor — analogue voltage corresponding to throttle plate angle; at idle approximately 0.5 V, fully open approximately 4.2 V (pin 20)
- Sensor Ground — common signal ground reference for analogue sensors (pin 21)
- Air Temperature Sensor — analogue voltage from the intake air temperature sensor; used to correct fuel delivery for air density (pin 26)
- Vehicle Speed Sensor — pulse signal from the transmission-mounted VSS used for speed-sensitive engine management functions (pin 32)
- Injector #1 — ECM-driven injector pulse for cylinder 1 (pin 101)
- Injector #3 — ECM-driven injector pulse for cylinder 3 (pin 103)
- Injector #2 — ECM-driven injector pulse for cylinder 2 (pin 110)
- Injector #4 — ECM-driven injector pulse for cylinder 4 (pin 112)