A-1 ~ No Malfunction Indicator Lamp (MIL)
Chart A-1 Wiring Diagram:
Chart A-1 - No Check Engine Light:
CIRCUIT DESCRIPTION
There should always be a steady "CHECK ENGINE" light, when the ignition is "ON" and engine stopped. Ignition voltage is supplied directly to the light bulb. The Electronic Control Module (ECM) will control the light and turn it "ON" by providing a ground path through CKT 03 to the ECM.
TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. Battery feed CKTs C16 and B1 protected by 60 amp main-1 fuse. Located at fuse and relay convenience center (R.H. side of engine compartment.
2. Using a test light connected to 12 volts, probe each of the system ground circuits to be sure a good ground is present. See Powertrain Management/Computers and Control Systems/Testing and Inspection/Procedures for connector views.
DIAGNOSTIC AIDS:
Engine runs OK, check:
- Faulty light bulb
- CKT A5 open
- Gauge fuse blown. This will result in no oil, or generator lights, seat belt reminder, etc.
Engine cranks, but will not run.
- Fusible link open
- 15 amp ignition fuse open (fuse box, under L.H. side of dash)
- 15 amp ECM fuse open (fuse and relay convenience center, R.H. side of engine compartment)
- Battery CKTs C16 and B1 to ECM open
- Ignition CKT A6 to ECM open
- Poor connection to ECM