The ECU - Electronic Control Unit in the 1996–1999 Nissan 180SX (S13 chassis) controls the SR20DET 2.0 L DOHC turbocharged inline-four engine via Nissan ECCS (Electronic Concentrated Control System), which provides sequential multi-point fuel injection and electronic ignition timing from a single control module. The S13 SR20DET ECU uses a 76-pin connector arrangement common to the S-chassis platform. ECCS manages fuelling, ignition advance, boost control signals, and idle speed as a closed-loop system using inputs from the mass air flow sensor, throttle position sensor, coolant temperature sensor, and oxygen sensor.
ECU - Electronic Control Unit Connector.
| 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 |
| 29 | Sensor Ground | Ground |
| 32 | Vehicle Speed Sensor | Speed |
| 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 ECU connector is a multi-pin header specific to the Nissan S13 platform. Only a subset of the full 76-pin connector is listed here. The ECCS control unit also exposes signal lines for the Nissan CONSULT serial diagnostic interface (CHK, IGN, RX, TX), accessible via the dashboard diagnostic connector.
Signals
- Tachometer Signal — engine speed output from the ECU to the instrument cluster tachometer, expressed as a pulse-width signal proportional to RPM.
- Mass Air Flow Sensor — analogue voltage input from the hot-wire MAF sensor measuring intake air mass; used by ECCS as the primary load input for fuelling calculations.
- Mass Air Flow Sensor Ground — dedicated signal ground for the MAF sensor reference circuit.
- Engine Coolant Temperature Sensor — analogue voltage input from the NTC thermistor coolant temperature sensor; used for cold-start enrichment and ignition timing correction.
- O2 Sensor Signal — analogue voltage input from the exhaust oxygen sensor; used for closed-loop lambda correction under part-load conditions.
- Throttle Position Sensor — analogue voltage input from the throttle body TPS; signals idle, part-load, and wide-open-throttle states to ECCS.
- Sensor Ground — common signal ground reference for multiple sensor circuits.
- Vehicle Speed Sensor — pulse signal from the gearbox-mounted VSS; used for speed-dependent idle correction and fuel cut functions.
- Injector #1, #2, #3, #4 — individual injector drive outputs from the ECU; ECCS fires each injector sequentially in cylinder-firing-order timing.
- Power Ground (Electronic Concentrated Control System) — high-current chassis ground return for the ECCS control unit power supply.