Malfunction Indicator Lamp On Steady
Malfunction Indicator Lamp ON SteadyWiring Diagram:
Circuit Description
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.
Test Description
Number(s) below refer to the step number(s) on the diagnostic table.
1. The On-Board Diagnostic (OBD II) 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.
2. 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.
3. A shorted MIL circuit can be diagnosed with a scan tool.
4. The replacement ECM must be reprogrammed. Refer to the latest Techline information for reprogramming procedures.
Step 1 - 8:
Troubleshooting