The 1991–1994 Nissan Sentra (B13 chassis) uses Nissan’s ECCS (Electronic Concentrated Control System) for engine management, covering GA16DE (1.6 L DOHC) and SR20DE (2.0 L DOHC naturally aspirated) variants. The ECU (Engine Control Unit) is a multi-pin unit that manages sequential multi-point fuel injection, electronic ignition timing, and sensor inputs. This platform is documented in the official Nissan B13/N14 Factory Workshop Manual, which covers the full range of 100NX, Sunny, and Sentra models sharing this architecture. OBD-I diagnostics are accessible via the ECCS self-diagnostic mode on these 1991–1994 model years.
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 table lists a partial selection of ECU connector pins. The B13 Sentra ECU uses the Nissan ECCS multi-pin connector format consistent with the broader B13/N14 platform. OBD-I self-diagnostics are triggered via the ECCS diagnostic mode; the 1995 model year marked the transition to OBD-II for US-market vehicles.
Signals
- Tachometer Signal — engine speed signal output from the ECU, used to drive the instrument cluster tachometer.
- 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 reference for the MAF sensor circuit.
- Engine Coolant Temperature Sensor — analogue input from the coolant temperature thermistor; used for fuel enrichment and idle speed correction.
- O2 Sensor Signal — analogue input from the exhaust oxygen sensor for closed-loop fuel trim.
- Throttle Position Sensor — analogue voltage input indicating throttle plate angle for load calculation and acceleration enrichment.
- Sensor Ground — common signal ground for analogue sensor inputs.
- Air Temperature Sensor — analogue input from the intake air temperature sensor; used for air density correction.
- Vehicle Speed Sensor — pulse signal input from the transmission speed sensor for speed-dependent functions.
- Power Ground (Electronic Concentrated Control System) — chassis power ground for the ECCS control unit (pins 48 and 116).
- Injector #1, #2, #3, #4 — individual injector drive outputs; signal column labelled “Speed” reflects the pulse-width modulated drive nature of the injector signal.