When the back-up lamp does not illuminate or extinguish normally, the power supply or the earth circuit to the back-up lamp or the inhibitor switch may be defective.
PROBABLE CAUSES
Malfunction of the inhibitor switch
Malfunction of bulbs
Malfunction of the back-up lamp assembly
Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. Bulb check
Check the bulb(s) of the lamp that does not illuminate.
Q.
Is the check result normal?
Go to Step 2.
Replace the bulb(s) of the lamp that does not illuminate.
STEP 2. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.
Q.
Is the diagnosis code set?
Troubleshoot the ETACS-ECU. Refer to .
Go to Step 3.
STEP 3. Check the inhibitor switch.
Check the continuity of the inhibitor switch. (GROUP 23A - On-vehicle Service, Inhibitor Switch Continuity Check .)
Q.
Is the check result normal?
Go to Step 4
Replace the inhibitor switch.
STEP 4. Voltage measurement at the inhibitor switch connector (power supply terminal).
(1)Remove the inhibitor switch connector, and measure at the junction block side.
(2)Move the ignition switch to the ON position.
(3)Measure the voltage between the inhibitor switch connector (power supply terminal) and body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 6
Go to Step 5
STEP 5. Check of open circuit in power supply line between the inhibitor switch connector and the fusible link.
Q.
Is the check result normal?
Go to Step 6
Repair the connector(s) or wiring harness.
STEP 6. Resistance measurement at the back-up lamp connector (earth terminal).
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the back-up lamp connector (earth terminal) and the body earth. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 8
Go to Step 7
STEP 7. Check of open circuit in earth line between the back-up lamp connector and body earth.
Q.
Is the check result normal?
Go to Step 8
Repair the connector(s) or wiring harness.
STEP 8. Check of open circuit in output line between the back-up lamp connector and inhibitor switch connector.
Q.
Is the check result normal?
Go to Step 9
Repair the connector(s) or wiring harness.
STEP 9. Retest the system
Check that the back-up lamp illuminate normally.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the bulb(s) of the lamp that does not illuminate.
.