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Inspection Procedure 13: The backup light switch signal is not received. <M/T>
 
 
cautionWhenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
Input signal from the backup light switch is used to operate the Hill Start Assist (HSA) system functions below. If the signal is abnormal, these functions will not work normally.
 
 
TROUBLESHOOTING HINTS
  • The backup light switch may be faulty.
  • The ETACS-ECU may be faulty.
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the operation of the backup lights.
Check that the backup lights illuminate normally.
Is the check result normal?
Go to Step 2.
Diagnose the rear combination lights (Refer to ). 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 ground.
OK:
  • When the shift lever is at the reverse position: Approx. battery positive voltage
  • When the shift lever is at other than the reverse position: 1V or less
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 backup light switch connector. Then go to Step 5.
 
STEP 3. Using scan tool (M.U.T.-III), read the other systems diagnostic trouble code.
Check if DTC is set in the ASC-ECU.
Is the DTC set?
Troubleshoot the ASC-ECU (Refer to GROUP 35C - diagnostic trouble 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.
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 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.
Is the check result normal?
This diagnosis is complete.
Return to Step 2.