Inspection Procedure 4
CIRCUIT OPERATION- The service engine soon/malfunction indicator lamp power is supplied from the ignition switch.
- The ECM or PCM controls the ground of the check engine/malfunction indicator lamp by turning the power transistor in the ECM or PCM "ON" and "OFF."
COMMENT
- In cases such as the above, the cause is probably that the ECM or PCM is detecting a problem in a sensor or actuator, or that one of the malfunctions listed at right has probably occurred.
TROUBLESHOOTING HINTS
The most likely causes for this case:
- Short-circuit between the service engine soon/malfunction indicator lamp and ECM.
- Short-circuit between the service engine soon/malfunction indicator lamp and PCM.
- Malfunction of the ECM
- Malfunction of the PCM .
WIRING DIAGRAM
CONNECTORS
DIAGNOSIS
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 1. Using scan tool MB991502, read the diagnostic trouble code (DTC).
If DTC is not output, go to Step 2.
If DTC is output, go to Trouble Code Diagnostic Procedures.
STEP 2. Check the circuit at the combination meter connector C-30.
1. Disconnect connector C-30 and measure at the harness side.
2. Disconnect the ECM connector C-36
3. Check for continuity between connector C-30 terminal 6 and ground.
- There should be no continuity.
If there is continuity, repair the harness wire between the combination meter connector C-30 and the ECM connector C-36