ECU - Electronic Control Unit Connector.
The Engine Control Module (ECM) in the 1996–1999 Acura Integra (DC2/DB8 chassis) is an OBD2 unit operating under Honda’s PGM-FI multi-point fuel injection architecture. It uses three connectors: a 32-pin A connector, a 31-pin C connector, and a 16-pin D connector. The ECM is mounted beneath the right-hand (passenger-side) kick panel and manages fuelling, ignition timing, the VTEC solenoid valve, the idle air control valve, and a suite of engine sensors. B18C1-equipped models (GS-R and Type R) carry a different ECU calibration (P72) from B18B1 models (LS/RS, P75), though the connector arrangement is identical across variants.
Connector A
| Pin | name | Signal |
|---|---|---|
| A8 | VTEC Solenoid Valve | Analog |
| A10 | Power Ground | Ground |
| A20 | Ignition Control Module | RPM |
| A23 | Power Ground | Ground |
Connector C
| Pin | name | Signal |
|---|---|---|
| C15 | VTEC Pressure Switch | Analog |
| C18 | Vehicle Speed Sensor | Speed |
Connector D
| Pin | name | Signal |
|---|---|---|
| D1 | Throttle Position Sensor | Analog |
| D2 | Engine Coolant Temperature Sensor | Analog |
| D3 | MAP Sensor | Analog 0.32V @ -13.9 PSI 4.84V @ 10.94 PSI |
| D5 | Brake Switch | Analog |
| D7 | Primary O2 Sensor | Analog |
| D8 | Intake Air Temperature Sensor | Analog |
| D14 | Secondary O2 Sensor | Analog |
Notes
Connector pins are numbered from the wire side (rear of connector) with the locking tab at the top; this orientation determines the pin numbering sequence. The OBD2 16-pin Data Link Connector (DLC), located under the dashboard, accepts a standard scan tool or the Honda PGM Tester for diagnostic trouble code (DTC) retrieval. To clear stored DTCs, disconnect the negative battery terminal for at least 30 seconds or remove the ECM backup fuse; note that this also erases idle-learn data, requiring an idle relearn procedure afterwards. The test harness OL0AT-PT3010A is interposed between the ECM and its connectors for live terminal voltage measurements.
Signals
- VTEC Solenoid Valve (A8) — ECM output that energises the VTEC oil-pressure switching solenoid to engage the high-lift camshaft profile at elevated RPM and load; present on B18C1 (GS-R/Type R) models only.
- Power Ground (A10, A23) — chassis/engine ground reference for the ECM power stage.
- Ignition Control Module (A20) — RPM timing signal exchanged between the ECM and the ignition control module.
- VTEC Pressure Switch (C15) — input confirming that oil pressure has risen sufficiently for VTEC engagement; ECM uses this to verify the solenoid has activated correctly.
- Vehicle Speed Sensor (C18) — pulse input from the transmission-mounted speed sensor; used by the ECM for fuel cut, idle control, and transmission-shift logic.
- Throttle Position Sensor (D1) — analogue voltage input indicating throttle plate angle; used for acceleration enrichment and idle detection.
- Engine Coolant Temperature Sensor (D2) — analogue input used for cold-start enrichment, cooling-fan control, and closed-loop lambda corrections.
- MAP Sensor (D3) — manifold absolute pressure input; output ranges from approximately 0.32 V at −13.9 PSI to 4.84 V at +10.94 PSI; primary engine-load signal for fuelling calculations.
- Brake Switch (D5) — input indicating brake pedal depression; used for torque-converter lock-up release (automatic transmission) and idle-up logic.
- Primary O2 Sensor (D7) — upstream heated oxygen sensor input for closed-loop air/fuel ratio control.
- Intake Air Temperature Sensor (D8) — analogue input for inlet air density compensation.
- Secondary O2 Sensor (D14) — downstream oxygen sensor input used for catalytic converter efficiency monitoring.