MIL Circuit

2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: MIL Circuit

MIL Circuit

DESCRIPTION

The Malfunction Indicator Lamp (MIL) is used to indicate vehicle malfunction detected by the ECM.
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 to the ON position, 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 the intelligent tester.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK THAT MIL IS ILLUMINATED
(a) Perform troubleshooting in accordance with the chart below.
Result:






B -- CHECK THAT MIL IS ILLUMINATED
A -- Continue to next step.
2. CHECK WHETHER MIL TURNS OFF
(a) Connect the intelligent tester 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.
3. CHECK WIRE HARNESS (FOR SHORT)





(a) Disconnect the E5 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 (COMBINATION METER - ECM)
4. CHECK THAT MIL IS ILLUMINATED
(a) Check if the MIL is illuminated when the ignition switch is turned to the ON position.
OK:
MIL should be illuminated.
OK -- SYSTEM OK
NG -- Continue to next step.
5. CHECK THAT ENGINE STARTS
(a) Turn the ignition switch to the ON position.
(b) Start the engine.
Result:





HINT: *: The intelligent tester cannot communicate with the ECM.

B -- GO TO VC OUTPUT CIRCUIT
A -- Continue to next step.
6. INSPECT COMBINATION METER (MIL CIRCUIT)
(a) See the combination meter troubleshooting procedure Meter / Gauge System.
NG -- REPAIR OR REPLACE BULB OR COMBINATION METER ASSEMBLY
OK -- CHECK AND REPAIR HARNESS AND CONNECTOR (COMBINATION METER - ECM)