The 1989–1994 Nissan 240SX (S13 chassis, North American market) uses a 64-pin ECM (Engine Control Module) connector as part of Nissan’s ECCS (Electronic Concentrated Control System), the factory sequential multi-point fuel injection and electronic ignition management system. Early 1989–1990 models were fitted with the KA24E single-overhead-camshaft 2.4-litre inline-four; from 1991 onwards the KA24DE twin-cam unit was standard. All S13 240SX ECMs operate under OBD-I diagnostics, accessible via the self-diagnostic mode described in the factory service manual.
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 |
| 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 ECM connector is a 64-pin Nissan-proprietary multi-pin header. The table above lists the documented signal pins; remaining pin positions are not publicly documented. The 1993 model year 240SX uses OBD-I diagnostics; self-diagnostic mode is entered via the ECM’s diagnostic test mode terminal. The transition to OBD-II did not occur on the S13 platform — 1995 marks the introduction of OBD-II on the S14 240SX.
Signals
- Tachometer Signal — engine speed output from the ECM to the instrument cluster tachometer, expressed in RPM.
- Mass Air Flow Sensor — analogue voltage input from the hot-wire MAF sensor measuring intake air mass.
- Mass Air Flow Sensor Ground — dedicated signal ground return for the MAF sensor circuit.
- Engine Coolant Temperature Sensor — analogue input from the NTC thermistor sensing engine coolant temperature; used by the ECM to adjust fuelling and ignition timing.
- O2 Sensor Signal — analogue voltage input from the upstream exhaust oxygen sensor for closed-loop fuel trim.
- Throttle Position Sensor — analogue voltage input indicating throttle plate angle; idle and wide-open-throttle thresholds are calibrated in the ECM.
- Sensor Ground — common signal ground reference for analogue sensor inputs.
- Air Temperature Sensor — analogue input from the intake air temperature sensor; used for air-density correction to fuelling calculations.
- Vehicle Speed Sensor — pulse signal input indicating road speed, used for speed-dependent fuel cut and idle stabilisation strategies.
- Power Ground (Electronic Concentrated Control System) — primary power ground for the ECCS control unit (pins 48 and 116 both serve this function).
- Injector #1 / #2 / #3 / #4 — low-side driver outputs from the ECM to each fuel injector solenoid for sequential multi-point injection.