When the ignition switch is turned ON, the malfunction indicator lamp (MIL) will be turned ON and remain ON until the engine is running, if no diagnostic trouble codes (DTCs) are stored. Battery voltage is supplied through the ignition switch directly to the MIL telltale. The engine control module (ECM) controls the MIL by providing a ground path through the MIL control circuit to turn ON the MIL.
The numbers below refer to the step numbers on the diagnostic table.
The On-Board Diagnostic System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is stored in the scan tool for later reference.
When the ignition is turned ON, the MIL should be turned ON and remain ON until the engine is running or if an emission related DTC is stored. This step checks the ability of the ECM to control the MIL. The scan tool has the ability to command the MIL ON and OFF.
A shorted MIL circuit can be diagnosed with a scan tool.
The replacement ECM must be reprogrammed. Refer to the latest Techline information for reprogramming procedures.
Step | Action | Yes | No |
---|---|---|---|
Perform an On-Board Diagnostic System Check. Is the check complete? | Go to Step 2 | ||
Does the MIL turn ON and OFF when commanded? | Go to Step 7 | Go to Step 3 | |
3 |
Is the MIL OFF? | Go to Step 6 | Go to Step 4 |
Inspect the MIL control circuit for a short to ground and repair as needed. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | |
5 | Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | Go to Step 7 | -- |
Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | Go to Step 7 | -- | |
7 |
Does the engine start and continue to run? | Go to Step 8 | Go to Step 1 |
8 |
Are any DTCs displayed that have not been diagnosed? | Go to applicable DTC table | System OK |