Malfunction Indicator Lamp: Testing and Inspection

Malfunction Indicator Lamp, significance

Functional check
- Switch ON ignition
- MIL lamp must light up until engine starts.
- The Glow plug indicator light can also light up during the pre-glow period if the engine is cold.

If MIL lamp does not light-up with ignition switched ON:
- Check MIL lamp wiring / MIL lamp bulb using wiring diagram.

If OK:
- Check instrument cluster / ECM and replace.
- Erase DTC memory.
- Set Readiness code.

If the MIL lamp lights-up with ignition switched on, continue check as follows:
- Start engine and let idle
- MIL lamp must switch OFF after a few seconds.

If MIL lamp does not switch OFF:
- Check DTC memory. Reading Diagnostic Trouble Codes If no malfunction stored:
- Check MIL lamp using wiring diagram.

If OK:
- Check instrument cluster / ECM and replace.
- Erase DTC memory.
- Set Readiness code.