Inspection Procedure 14: The back-up lamp switch signal is not received <M/T>.


caution Whenever the ECU is replaced, ensure that the input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM


Input signal from the back-up lamp switch is used to operate the HSA system functions below. If the signal is abnormal, these functions will not work normally.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Check the operation of the back-up lamps.
Check that the back-up lamps illuminate normally.

Q. Is the check result normal?
Go to Step 2.
Diagnose the rear combination lamps (Refer to Rear Combination lamp, Symptom procedures 3 ). Then go to Step 5.

STEP 2. Voltage measurement at ETACS-ECU connector (BACK terminal).
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the "ACC" position.
(3)Check the voltage between the ETACS-ECU connector (BACK terminal) and body earth.
OK:
    When the shift lever is at the reverse position: Approx. system voltage
    When the shift lever is at other than the reverse position: 1V or less

Q. Is the check result normal?
Go to Step 3.
The power supply circuit may be open or short. Repair the connectors or the wiring harness wires between the ETACS-ECU connector and the back-up lamp switch connector. Then go to Step 5.

STEP 3. Use M.U.T.-III to confirm a diagnosis code of other system.
Check if the diagnosis code is set in the ASC-ECU.

Q. Is the diagnosis code set?
Troubleshoot the ASC-ECU diagnosis code (Refer to GROUP 35C - Diagnosis Code Chart ). Then go to Step 5.
Go to Step 4.

STEP 4. Retest the system.
Check if the HSA works with one person on the driver’s seat.

Q. Is the check result normal?
The trouble can be an intermittent malfunction.
Replace the ETACS-ECU. Then go to Step 5.

STEP 5. Retest the system.
Check if the HSA works with one person on the driver’s seat.

Q. Is the check result normal?
This diagnosis is complete.
Return to Step 2.