Step 1. MUT-II/III diagnosis code

When the ignition switch is turned to the LOCK (OFF) position, check that the ETACS-ECU does not set the diagnosis code.

Q: Is the diagnosis code set?

YES:  Refer to diagnosis code chart .
NO:  Go to Step 2.

Step 2. Pulse check

Check the input signals below, which are related to the tail lamps.

System switch	Check condition
Ignition switch (IG1)	When turned from ACC to ON
Tail lamp switch	When the lighting switch is turned to the TAIL position

OK: The MUT-II/III sounds or the voltmeter needle fluctuates.

Q: Is the check result normal?

All the signals are received normally.:  Go to Step 3.
The ignition switch (IG1) signal is not received.:  Refer to Inspection Procedure P-2 "The ignition switch (IG1) signal is not received ."
The tail lamp switch signal is not received.:  Refer to Inspection Procedure P-5 "The column switch (lighting and turn-signal lamp switch) signal is not received ."

Step 3. Connector check: A-11X front-ECU connector

Q: Is the check result normal?

YES:  Go to Step 4.
NO:  Repair the defective connector.

Step 4. Measure the voltage at A-11X front-ECU connector.

1. Remove the front-ECU, and measure at the relay box side.

2. Voltage between A-11X front-ECU connector terminal No.7 and body earth
OK: Battery positive voltage

Q: Is the check result normal?

YES:  Go to Step 6.
NO:  Go to Step 5.

Step 5. Check the wiring harness between A-11X front-ECU connector terminal No.7 and the battery.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES:  The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
NO:  Repair the wiring harness.

Step 6. Retest the system.

Check that the tail lamps illuminate normally.

Q: Is the check result normal?

YES:  The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
NO:  Replace the front-ECU.