The ECU - Electronic Control Unit fitted to the 1992–1995 Honda Del Sol is the OBD1-era PGM-FI (Programmed Fuel Injection) control unit shared with the contemporary Civic EG/EH chassis. The Del Sol S uses a D15B7 engine (P06 ECU), the Si uses a D16Z6 (P28 ECU), and the VTEC model uses a B16A2 (P30 ECU). The ECU is mounted above the passenger footwell and uses a two-connector arrangement (A and B) plus a supplementary D connector. Diagnostic trouble codes are retrieved via a two-pin service check connector using MIL blink codes, as the OBD1 generation predates the standardised 16-pin OBD2 Data Link Connector introduced in 1996.
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 |
|---|---|---|
| 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
- Connector pins are read from the wire side (back of connector) with the locking tab at the top; this orientation determines the pin numbering sequence.
- The VTEC solenoid valve output (A4) and VTEC pressure switch input (D6) are present only on VTEC-equipped variants (B16A2 engine, P30 ECU). Non-VTEC variants (P06, P28) leave these circuits unpopulated.
- To clear stored diagnostic trouble codes, disconnect the negative battery terminal for at least 30 seconds, or remove the ECU back-up fuse. This also erases the idle learn data, requiring an idle relearn procedure afterwards.
- The MAP sensor signal (D17) ranges from approximately 0.32 V at −13.9 PSI (high vacuum) to 4.84 V at +10.94 PSI (boost).
- The OBD1 P-series ECUs (P06, P28, P30) used across the Del Sol, Civic, Integra, and CRX share the same two-connector architecture and are cross-compatible via wiring harness adapters.
Signals
- VTEC Solenoid Valve (A4) — ECU output that energises the VTEC oil-pressure solenoid to switch cam profiles at the programmed RPM threshold; present on B16A2 (P30 ECU) only.
- Ignition Control Module (A21) — RPM signal output from the ECU to the ignition control module for ignition timing control.
- Power Ground (A24) — chassis ground reference for the ECU.
- Vehicle Speed Sensor (B10) — vehicle speed pulse signal input to the ECU from the speed sensor.
- Voltage Back Up (D1) — permanent battery supply that maintains ECU memory (DTCs, idle learn data) when the ignition is off.
- Brake Switch (D2) — input indicating brake pedal actuation; used by the ECU for fuel cut and idle control logic.
- VTEC Pressure Switch (D6) — oil pressure switch input confirming VTEC engagement; present on VTEC variants only.
- Throttle Position Sensor (D11) — analogue voltage input (0–5 V) proportional to throttle plate angle.
- Engine Coolant Temperature Sensor (D13) — negative-temperature-coefficient (NTC) thermistor input; ECU uses this for cold-start enrichment and cooling fan control.
- Primary O2 Sensor (D14) — upstream oxygen sensor signal input; ECU uses this for closed-loop fuel trim.
- Intake Air Temperature Sensor (D15) — NTC thermistor input for inlet air temperature; ECU applies air-density correction to fuelling.
- MAP Sensor (D17) — manifold absolute pressure sensor analogue input; ECU calculates engine load from this signal.