Chart A1 - No "Check Engine" Light
The "CHECK ENGINE" light should come on when ignition is turned "ON" and engine is not running. Battery voltage is supplied directly to bulb. The ECM controls the light by grounding circuit 419.
If engine runs, no "CHECK ENGINE" light indicates a defective bulb, blown fuse or open control circuit 419. If engine cranks but will not run, no "CHECK ENGINE" light indicates a blown battery fuse, blown fusible link, ECM ignition fuse blown, battery circuit 340 to ECM open, ignition circuit 439 to ECM open or poor connection to ECM.
NOTE:
The following step numbers refer to the step numbers in the accompanying Flow Chart.
- Solenoids and relays are turned "ON" or "OFF" by ECM, using electronic switches called "drivers". Each driver is part of a group of 4, called "Quad-Drivers". Failure of 1 driver can damage other drivers in set. Solenoid and relay coil resistance must be more than 20 ohms, as less resistance will cause early failure of ECM drivers.