Chart A1-1 No Malfunction Indicator Lamp (MIL)

Chart A1-1 No MIL:

Malfunction Indicator Lamp Circuit:

CIRCUIT DESCRIPTION
There should always be a steady Malfunction Indicator Lamp (MIL) when the ignition is in the "ON" position and the engine is not running. System voltage is applied to the light bulb. The Engine Control Module (ECM) will control the MIL and turn it "ON" by providing a ground path through the Purple (PPL) wire shown in the accompanying schematic.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. Checks to see if ECM is receiving power.
2. Checks to see if ECM is faulty.
3. Checks for an open in WHT/BLU wire between FI relay and ECM.
4. Checks to see if ECM has a good ground.
5. Checks for an open in BLK/WHT wire to Instrument Panel (I/P) or in PPL wire to ECM.
6. Checks to see if FI relay switch is receiving power.
7. Checks to see if FI relay coil is receiving power.
8. Checks to see if FI relay or ECM is faulty, or for an open in BLK wire between FI relay and ground.

DIAGNOSTIC AIDS
Be sure to check connectors for contamination, corrosion or bent terminals.