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Code No. C1291 Reverse switch <M/T>
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
  • When the hydraulic unit assembly (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).
 
 
OPERATION
The back-up light switch output signal is sent to ASC-ECU via the CAN bus lines.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
When the power supply and wheel speed sensor are normal and ASC-ECU receives the signal that the shift lever is at the reverse position while the vehicle drives at 40 km/h or more.
 
 
PROBABLE CAUSES
Current trouble
  • Blown fuse
  • Damaged wiring harness or connector
  • Malfunction of the back-up light switch
  • Malfunction of the ETACS-ECU
  • Malfunction of the hydraulic unit assembly (integrated with ASC-ECU)
Past trouble
  • Carry out diagnosis with particular emphasis on the back-up light switch, connector(s) or wiring harness between the back-up light switch to the junction block or ETACS-ECU. For diagnosis procedures, refer to How to treat past trouble. (GROUP 00, How to Use Troubleshooting/Inspection Service Points ).
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus lines.
Use scan tool (M.U.T.-III) to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus line (Refer to GROUP 54C, Troubleshooting ). On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Is the relevant diagnostic trouble code No. C1291 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Check the back-up light
(1) Turn the ignition switch to the "ON" position.
(2) Check how the back-up light operates correctly when you move the shift lever.
OK:
  • When the shift lever is moved to R position: Illuminate
  • When the shift lever is moved to any position other than R: OFF
Is the check result normal?
Go to Step 10.
<comes on> : The back-light switch circuit may be short. Repair the wiring harness wires or connectors between the back-up light switch and the ETACS-ECU connector back terminal or the junction block. Then go to Step 4.
<goes out> : The back-light switch circuit may be open. Repair the wiring harness wires or connectors between the back-up light switch and the ETACS-ECU connector back terminal or the junction block. Then go to Step 6.
 
STEP 4. Check the back-up light switch.
Check the continuity of the back-up light switch (Refer to GROUP 22B, Transmission, inspection ).
Is the check result normal?
Go to Step 5.
Replace the back-up light switch (Refer to GROUP 22B, Transmission ). Then go to Step 12.
 
STEP 5. Measure the resistance at the back-up switch connector
(1) Remove the back-up light switch connector, junction block connector and ETACS-ECU connector.
(2) Check the back-up light switch connector.
(3) Disconnect the connector and measure at the wiring harness side.
(4) Measure the resistance between the back-up light switch connector terminals and body ground.
OK: No continuity
Is the check result normal?
Go to Step 10.
The back-up light switch circuit may be short. Repair the wiring harness wires or connectors between the back-up light switch connector terminals and the junction block or ETACS-ECU connector. Then go to Step 12.
 
STEP 6. Check the fuse No.21
Is the check result normal?
Go to Step 7.
Replace the fuse No.21. Then go to Step 9.
 
STEP 7. Check the back-up light switch.
Check the continuity of the back-up light switch (Refer to GROUP 22B, Transmission, inspection ).
Is the check result normal?
Go to Step 8.
Replace the back-up light switch (Refer to GROUP 22B, Transmission ).
 
STEP 8. Measure the resistance at the back-up switch connector
(1) Remove the back-up light switch connector, junction block connector and ETACS-ECU connector.
(2) Check the back-up light switch connector.
(3) Disconnect the connector and measure at the wiring harness side.
(4) Measure the resistance between the back-up light switch connector terminals and junction block connector or ETACS-ECU connector.
OK: Continuity exists (2 Ω or less).
Is the check result normal?
Go to Step 10.
The back-up light switch circuit may be open. Repair the wiring harness wires or connectors between the back-up light switch connector terminals and the junction block or ETACS-ECU connector. Then go to Step 12.
 
STEP 9. Measure the resistance at the back-up switch connector
(1) Remove the back-up light switch connector, junction block connector and ETACS-ECU connector.
(2) Check the back-up light switch connector.
(3) Disconnect the connector and measure at the wiring harness side.
(4) Measure the resistance between the back-up light switch connector terminals and body ground.
OK: No continuity
Is the check result normal?
Go to Step 10.
The back-up light switch circuit may be short. Repair the wiring harness wires or connectors between the back-up light switch connector terminals and the junction block or ETACS-ECU connector, or replace the fuse No.21. Then go to Step 12.
 
STEP 10. Check whether the diagnostic trouble code is set again.
Check again if the diagnostic trouble code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnostic trouble code.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Move the shift lever to the R position, and hold it for at least one second.
(6) Move the shift lever to the neutral position, and hold it for at least one second.
(7) Check if the diagnostic trouble code is set.
(8) Turn the ignition switch to the "LOCK" (OFF) position.
Is code No.C1291 set?
Replace the ETACS-ECU (Refer to GROUP 54A, ETACS-ECU ). Then go to Step 11.
Intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunctions ).
 
STEP 11. Check whether the diagnostic trouble code is set again.
Check again if the diagnostic trouble code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnostic trouble code.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Move the shift lever to the R position, and hold it for at least one second.
(6) Move the shift lever to the neutral position, and hold it for at least one second.
(7) Check if the diagnostic trouble code is set.
(8) Turn the ignition switch to the "LOCK" (OFF) position.
Is code No.C1291 set?
Replace the hydraulic unit assembly (integrated with ASC-ECU) (Refer to ). Then go to Step 12.
The procedure is complete.
 
STEP 12. Check whether the diagnostic trouble code is set again.
Check again if the diagnostic trouble code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnostic trouble code.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Move the shift lever to the R position, and hold it for at least one second.
(6) Move the shift lever to the neutral position, and hold it for at least one second.
(7) Check if the diagnostic trouble code is set.
(8) Turn the ignition switch to the "LOCK" (OFF) position.
Is code No.C1291 set?
Return to Step 3.
The procedure is complete.