MIL Circuit

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





INSEPCTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following 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 to ON and turn the Techstream on.

(c) Check if DTCs have been stored Diagnostic Trouble Code Descriptions. If DTCs are present, write them down.

(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(e) Check that the MIL turns off.

OK:

MIL turns off.

NG -- CHECK HARNESS AND CONNECTOR (FOR SHORT)

OK -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

3. CHECK HARNESS AND CONNECTOR (FOR SHORT)





(a) Disconnect the E5 ECM connector.

(b) Turn the ignition switch to ON.

(c) Check that the MIL is not illuminated.

OK:

MIL is not illuminated.

NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM)

OK -- REPLACE ECM Service and Repair

4. CHECK HARNESS AND CONNECTOR (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 OR CONNECTOR

OK -- REPAIR OR REPLACE COMBINATION METER Removal and Replacement

5. CHECK THAT MIL IS ILLUMINATED

(a) Check that the MIL is illuminated when turning the ignition switch to ON.

OK:

MIL is illuminated.

NG -- CHECK THAT ENGINE STARTS

OK -- END

6. CHECK THAT ENGINE STARTS

(a) Turn the ignition switch to 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 HARNESS AND CONNECTOR (COMBINATION METER - BODY GROUND)





(a) Disconnect the E5 ECM connector.

(b) Turn the ignition switch to ON.

(c) Measure the voltage of the wire harness side connectors

Standard Voltage:





NG -- CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM)

OK -- REPLACE ECM Service and Repair

8. CHECK HARNESS AND CONNECTOR (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 OR CONNECTOR

OK -- REPAIR OR REPLACE COMBINATION METER Removal and Replacement