Malfunction Indicator Lamp: Testing and Inspection

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

MIL Circuit

DESCRIPTION

The Malfunction Indicator Lamp (MIL) is used to indicate the ECM's detection of a vehicle malfunction.
The instrument panel D-IG fuse provides the circuit with 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 turned ON. If the MIL is always ON or OFF, use the Techstream and follow the procedures below to determine the cause of the problem.
If the ECM detects trouble, the MIL illuminates. At this time, the ECM records a DTC in the memory.

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 IF MIL TURNS OFF
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Check if DTCs have been stored SFI System. If DTCs are present, write them down.
(d) Clear the DTCs DTC Check / Clear.
(e) Check that the MIL turns off.
OK:
MIL turns off.
OK -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCS
NG -- Continue to next step.
3. CHECK WIRE HARNESS (FOR SHORT)




(a) Disconnect the E5 ECM connector.
(b) Turn the ignition switch ON.
(c) Check that the MIL is not illuminated.
OK:
MIL is not illuminated.
OK -- REPLACE ECM
NG -- Continue to next step.
4. CHECK WIRE HARNESS (COMBINATION METER - ECM)




(a) Disconnect the C8 combination meter connector.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPAIR OR REPLACE COMBINATION METER
5. CHECK THAT MIL IS ILLUMINATED
(a) Check that the MIL is illuminated when turning the ignition switch ON.
OK:
MIL is illuminated.
OK -- SYSTEM OK
NG -- Continue to next step.
6. CHECK THAT ENGINE STARTS
(a) Turn the ignition switch ON.
(b) Start the engine.
Result:





HINT: *: The Techstream cannot communicate with the ECM.

B -- GO TO VC OUTPUT CIRCUIT
A -- Continue to next step.
7. CHECK WIRE HARNESS (COMBINATION METER - BODY GROUND)




(a) Disconnect the E5 ECM connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage of the wire harness side connectors
Standard voltage:






OK -- REPLACE ECM
NG -- Continue to next step.
8. CHECK WIRE HARNESS (COMBINATION METER - ECM)




(a) Disconnect the C8 combination meter connector.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPAIR OR REPLACE COMBINATION METER