MIL Circuit
2UZ-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 GAUGE 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 MILL IS ILLUMINATED
(a) Perform troubleshooting in accordance with the chart below.
B -- CHECK THAT MIL IS ILLUMINATED
A -- Continue to next step.
2. CHECK WHETHER MIL TURNS OFF
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Check whether any DTCs have been stored. Note them down if necessary.
(d) Clear the DTC DTC Check / Clear.
(e) 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 HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)
(a) Disconnect the E7 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 HARNESS AND CONNECTOR (COMBINATION METER - ECM)
(a) Check the harness and connector.
OK -- REPAIR OR REPLACE COMBINATION METER
NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
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. INSPECT COMBINATION METER (MIL CIRCUIT)
(a) See the combination meter troubleshooting section Meter / Gauge System.
NG -- REPAIR OR REPLACE COMBINATION METER
OK -- CHECK AND REPLACE HARNESS OR CONNECTOR (COMBINATION METER - ECM)