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INSPECTION PROCEDURE 22: Backup light does not light up normally
 
 
 
 
COMMENTS ON TROUBLE SYMPTOM
When the back-up light does not illuminate or extinguish normally, the power supply or the ground circuit to the back-up light or the transmission range switch may be defective.
 
 
PROBABLE CAUSES
  • Malfunction of the back-up light relay
  • Malfunction of the back-up light assembly
  • Malfunction of the bulbs
  • Damaged harness or connector
  • Malfunction of the ETACS-ECU.
  • Malfunction of the PHEV-ECU.
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Bulb check
Check the bulb(s) of the light that does not illuminate.
Is the check result normal?
Go to Step 2.
Replace the bulb(s).
 
STEP 2. Check the power supply fuses (fuse No. 20)
Check the power supply fuses (fuse No. 20). (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - Inspection Service Points for a Blown Fuse .)
Is the fuse in good condition?
Go to Step 3
Replace the fuses.
 
STEP 3. Check back-up light relay.
Refer to GROUP 54A- Back-up light relay check .
Is the check result normal?
Go to Step 4.
Replace the back-up light relay.
 
STEP 4. Check of short to ground, and open circuit in the signal line. (Back-up light relay connector and ETACS-ECU connector).
  • Check the wiring harness between ETACS-ECU connector (terminal BLP+) and the back-up light relay connector (terminal No.4).
  • Check the wiring harness between ETACS-ECU connector (terminal BLP1) and the back-up light relay connector (terminal No.3).
Is the check result normal?
Go to Step 5.
Repair the connector or wiring harness.
 
STEP 5. Check of short to ground, and open circuit in the power supply line (ETACS-ECU connector and Back-up light <LH, RH> connector).
Check the wiring harness between ETACS-ECU connector (terminal BLP2) and the back-up light <LH, RH> connector (terminal No.2).
Is the check result normal?
Go to Step 6.
Repair the connector or wiring harness.
 
STEP 6. Check of short to ground, and open circuit in the ground line (Back-up light <LH, RH> connector and body ground).
Check the wiring harness between back-up light <LH, RH> connector (terminal No.1) and body ground.
Is the check result normal?
Go to Step 7.
Repair the connector or wiring harness.
 
STEP 7. Retest the system.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU. (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 8.
 
STEP 8. Retest the system.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Replace the PHEV-ECU (Refer to ).