MIL Circuit

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

MIL Circuit

DESCRIPTION

The MIL (Malfunction Indicator Lamp) is used to indicate malfunction detections by the ECM (Included in HV control ECU).
By turning the ignition switch to the ON position, power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.
The MIL operation can be checked visually: When the ignition switch is first turned on, the MIL should be illuminated and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using Techstream.

WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Troubleshoot each trouble symptom in accordance with the chart below.





PROCEDURE

1. CHECK WHETHER MIL TURNS OFF
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester ON.
(d) Check whether any DTCs have been stored DTC Check / Clear. Note them down if necessary.
(e) Clear the DTCs DTC Check / Clear.
(f) Check if the MIL turns off.
OK:
MIL should turn off.
OK -- REPAIR CIRCUIT INDICATED BY OUTPUT DTC
NG -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)





(a) Disconnect the H29 HV control ECU connector.
(b) Turn the ignition switch to the ON position.
(c) Check the MIL is not illuminated.
OK:
MIL is not illuminated.
(d) Reconnect the HV control ECU connector.
OK -- REPLACE HV CONTROL ECU
NG -- CHECK AND REPAIR HARNESS AND CONNECTOR (COMBINATION METER - HV CONTROL ECU)
3. CHECK THAT MIL IS ILLUMINATED
(a) Check if the MIL is illuminated when the ignition switch is turned on.
OK:
MIL should be illuminated.
OK -- SYSTEM OK
NG -- Continue to next step.
4. INSPECT COMBINATION METER ASSEMBLY (MIL CIRCUIT)
(a) See the combination meter troubleshooting procedure Problem Symptoms Table.
NG -- REPAIR OR REPLACE BULB OR COMBINATION METER ASSEMBLY
OK -- CHECK AND REPAIR HARNESS AND CONNECTOR (COMBINATION METER - HV CONTROL ECU)