ECU - Electronic Control Unit Connector.
The 1992–1995 Acura Integra uses Honda’s PGM-FI (Programmed Fuel Injection) engine management system, an OBD1-era multi-point fuel injection architecture shared with contemporary Honda B-series platforms. The ECU is mounted in the passenger-side kick panel area and communicates with sensors and actuators through lettered multi-pin connectors (A, B, D). Models fitted with B18C1 (GSR) and B18B1 (LS/RS) engines use the same connector layout but different ECU calibrations — P72 for GSR and P75 for LS variants. Fault codes are retrieved via a 2-pin service check connector and MIL blink codes; no OBD2 Data Link Connector is fitted.
Connector A
| Pin | name | Signal |
|---|---|---|
| A4 | VTEC Solenoid Valve | Analog |
| A21 | Ignition Control Module | RPM |
| A24 | Power Ground | Ground |
Connector B
| Pin | name | Signal |
|---|---|---|
| B10 | Vehicle Speed Sensor | Speed |
Connector D
| Pin | name | Signal |
|---|---|---|
| D1 | Voltage Back Up | Power |
| D2 | Brake Switch | Analog |
| D6 | VTEC Pressure Switch | Analog |
| D11 | Throttle Position Sensor | Analog |
| D13 | Engine Coolant Temperature Sensor | Analog |
| D14 | Primary O2 Sensor | Analog |
| D15 | Intake Air Temperature Sensor | Analog |
| D17 | MAP Sensor | Analog 0.32V @ -13.9 PSI 4.84V @ 10.94 PSI |
Notes
Connectors are read from the wire side (rear of connector) with the locking tab at the top; this orientation determines pin numbering. The 26-pin connector A and 22-pin connector B are the primary ECU interfaces. A test harness (Honda part OL0AT-PT3010A) can be inserted between the ECU and connectors to allow live terminal voltage measurements during diagnostics without back-probing. To clear stored diagnostic trouble codes, disconnect the negative battery terminal for at least 30 seconds or remove the ECM backup fuse; this also clears idle learn data, requiring an idle relearn procedure afterwards.
Signals
- VTEC Solenoid Valve (A4) — output signal from the ECU that opens the VTEC oil control solenoid, switching cam profiles on VTEC-equipped engines (B18C1 GSR)
- Ignition Control Module (A21) — RPM signal exchanged with the ignition control module for timing and engine speed reference
- Power Ground (A24) — chassis ground reference for the ECU; used as the ground reference for terminal voltage measurements
- Vehicle Speed Sensor (B10) — vehicle speed pulse signal fed to the ECU for fuel and ignition correction
- Voltage Back Up (D1) — battery-backed supply that preserves ECU memory and stored DTCs when the ignition is off
- Brake Switch (D2) — brake pedal position input; used by the ECU for fuel cut and idle control logic
- VTEC Pressure Switch (D6) — input confirming hydraulic oil pressure has reached the VTEC engagement threshold; the ECU monitors this to verify solenoid actuation
- Throttle Position Sensor (D11) — analogue voltage input indicating throttle plate angle for load calculation and acceleration enrichment
- Engine Coolant Temperature Sensor (D13) — analogue input used for cold-start enrichment, idle speed correction, and cooling fan control
- Primary O2 Sensor (D14) — exhaust oxygen sensor signal for closed-loop fuel trim
- Intake Air Temperature Sensor (D15) — analogue input for inlet air density correction to fuel delivery calculations
- MAP Sensor (D17) — manifold absolute pressure sensor; analogue voltage ranging from approximately 0.32 V at −13.9 PSI to 4.84 V at 10.94 PSI, used as the primary engine load signal