Malfunction Indicator Lamp: Testing and Inspection

3MZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: MIL Circuit

MIL Circuit

DESCRIPTION

The MIL is used to indicate the ECM's detection of a vehicle malfunction.
The instrument panel GAUGE fuse provides the circuit power and the ECM provides the circuit ground that illuminates the MIL.
MIL operations should be checked visually:
The MIL should be illuminated when the ignition switch is first turned to the ON position. If the MIL is always ON or OFF, use Techstream or OBD II scan tool and follow the procedures below to determine the cause of the problem.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT: Troubleshoot each problem symptom in accordance with the chart below.





PROCEDURE

1. CLEAR DTC
(a) Connect Techstream or OBD II scan tool to the DLC3.
(b) Turn the ignition switch to the ON position and push Techstream or the OBD II scan tool main switch ON.
(c) Read the DTC.
(d) Clear the DTC (DTC Check / Clear).
(e) Check that the MIL is not illuminated.
OK:
MIL is not illuminated.
OK -- REPAIR CIRCUIT INDICATED BY OUTPUT DTC
NG -- Continue to next step.
2. CHECK WIRE HARNESS (CHECK FOR SHORT IN WIRE HARNESS)





(a) Disconnect the ECM connector.
(b) Turn the ignition switch to the ON position.
(c) Check that the MIL is not illuminated.
OK:
MIL is not illuminated.
OK -- REPLACE ECM
NG -- CHECK AND REPAIR HARNESS AND CONNECTOR
3. CHECK THAT MIL IS ILLUMINATED
(a) Check that the MIL is illuminated when turning the ignition switch to the ON position.
Standard:
MIL is illuminated.
OK -- SYSTEM OK
NG -- Continue to next step.
4. INSPECT COMBINATION METER (MIL CIRCUIT)
(a) See the combination meter troubleshooting (Problem Symptoms Table).
NG -- REPAIR OR REPLACE BULB OR COMBINATION METER
OK -- CHECK AND REPLACE HARNESS AND CONNECTOR (COMBINATION METER - ECM)