The 1992–1995 Honda Accord (CB7/CB9 chassis) uses Honda’s PGM-FI (Programmed Fuel Injection) system managed by an ECU mounted in the passenger compartment. The 1992–1993 models straddle the OBD0/OBD1 transition, while 1994–1995 models are fully OBD1; all use F22A or F22B series four-cylinder engines. The ECU employs alphabetically lettered multi-pin connectors (A, B, D) and retrieves diagnostic trouble codes via a service check connector using MIL blink codes rather than a standardised diagnostic port. On VTEC-equipped variants, the ECU also controls the VTEC solenoid valve and monitors the VTEC oil pressure switch.
ECU - Electronic Control Unit Connector.
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 |
|---|---|---|
| D2 | Brake Switch | Analog |
| D6 | VTEC Pressure Switch | Analog |
| D11 | Throttle Position Sensor | Analog |
| D13 | Engine Coolant Temperature Sensor | Analog |
| D14 | Primary 02 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 (back of connector) with the locking tab at the top; this orientation determines pin numbering.
- The ECU is located in the passenger compartment, typically behind the passenger-side kick panel trim.
- DTC retrieval on OBD0/OBD1 models uses a 2-pin service check connector; shorting the terminals causes the MIL to flash stored trouble codes. A 16-pin OBD2 DLC is not fitted on these models.
- To clear stored DTCs, disconnect the negative battery terminal for at least 30 seconds or remove the ECM back-up fuse. Note that this also clears idle learn data, requiring an idle relearn procedure.
- VTEC solenoid valve (A4) and VTEC pressure switch (D6) are present only on VTEC-equipped engine variants (e.g. F22B1 VTEC).
Signals
- VTEC Solenoid Valve (A4) — ECU output that activates the VTEC rocker-arm switching mechanism at the programmed engine speed threshold; present on VTEC-equipped variants only.
- Ignition Control Module (A21) — RPM signal line between the ECU and ignition control module; used by the ECU to calculate engine speed and control ignition timing.
- Power Ground (A24) — chassis/power ground reference for the ECU.
- Vehicle Speed Sensor (B10) — pulse signal from the vehicle speed sensor; used by the ECU to calculate road speed for fuel and idle control strategies.
- Brake Switch (D2) — input indicating brake pedal application; used for torque converter lock-up control on automatic transmission variants and idle-up logic.
- VTEC Pressure Switch (D6) — input confirming adequate oil pressure for VTEC engagement; ECU monitors this to verify the solenoid valve has successfully switched the rocker arms.
- Throttle Position Sensor (D11) — analogue voltage input indicating throttle plate angle; used for load calculation, acceleration enrichment, and deceleration fuel cut.
- Engine Coolant Temperature Sensor (D13) — analogue input (NTC thermistor) reporting coolant temperature; used for cold-start enrichment, fan control, and closed-loop fuel corrections.
- Primary O2 Sensor (D14) — exhaust oxygen sensor signal used for closed-loop lambda (air/fuel ratio) correction; switches between rich and lean around stoichiometry.
- Intake Air Temperature Sensor (D15) — analogue NTC input reporting inlet air temperature; used to correct injector pulse width for air density variations.
- MAP Sensor (D17) — manifold absolute pressure sensor; analogue voltage proportional to intake vacuum/boost. Voltage spans approximately 0.32 V at −13.9 PSI to 4.84 V at 10.94 PSI; primary load input for PGM-FI fuel calculations.
References
- Honda Accord 1990–1993 Repair Manual — Honda Motor Co.
- Honda Accord 1994 Service Manual — Honda Motor Co.