ECU - Electronic Control Unit Connector.
The Nissan S15 Silvia (1999–2002) uses the SR20DET 2.0 litre DOHC turbocharged inline-four engine managed by Nissan’s ECCS (Electronic Concentrated Control System), a sequential multi-point fuel injection and electronic ignition system controlled by a single ECM. The ECM communicates with sensors and actuators through a multi-pin connector array and exposes a CONSULT serial diagnostic interface via a dedicated data link connector. The S15 is the final evolution of the Silvia S-chassis line, sharing the SR20DET ECCS architecture introduced on the S13 platform.
Connector A
| 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 |
| 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 connector shown covers Connector A of the S15 SR20DET ECM. The high pin numbers for injector outputs (101–116) are consistent with the Nissan ECCS expanded terminal numbering used on S-chassis models from the S14 onward, where the ECM integrates additional control functions requiring a larger connector array. The CONSULT diagnostic interface is accessible via a 14-pin data link connector on the dashboard harness; the ECM exposes CHK, IGN, RX, and TX signal lines to this port.
Signals
- Tachometer Signal — engine speed output to the instrument cluster tachometer, derived from the crank angle sensor processed by the ECM
- Mass Air Flow Sensor — analogue voltage signal from the hot-wire MAF sensor used by the ECM to calculate intake air mass
- Mass Air Flow Sensor Ground — dedicated signal ground return for the MAF sensor circuit
- Engine Coolant Temperature Sensor — analogue voltage from the NTC thermistor used for cold-start enrichment and cooling fan control
- O2 Sensor Signal — analogue voltage from the upstream heated oxygen sensor used for closed-loop fuelling correction
- Throttle Position Sensor — analogue voltage (approximately 0.5 V at idle, 4.2 V at wide-open throttle) indicating throttle plate angle
- Sensor Ground (pins 21 and 29) — common signal ground reference for analogue sensor inputs; two separate ground pins reduce noise in the sensor circuit
- Vehicle Speed Sensor — pulse signal from the transmission-mounted VSS used for idle-up control and speed-dependent functions
- Injector #1 / #2 / #3 / #4 — sequential injector drive outputs; the ECM switches each injector to ground to trigger fuel delivery in firing order
- Power Ground (ECCS) — high-current ground return for the ECM power supply within the ECCS circuit