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Code No. C1340 Stop light switch
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be stored. 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 (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 ASC-ECU monitors the ON/OFF signals from the stop light switch and the pressure sensor (incorporated in the hydraulic unit).
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
This diagnostic trouble code is stored in the following case.
  • When the vehicle has been driven for a long time with the stop light switch turned ON.
  • The vehicle is being stopped although the stop light switch remains off.
 
 
PROBABLE CAUSES
  • The CAN bus line is defective.
  • Improper adjustment of stop light switch installation position
  • Malfunction of stop light switch
  • ETACS-ECU malfunction
  • Damaged harness wires and connectors
  • Malfunction of ASC-ECU
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use the scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines. (Refer to GROUP 54C - Troubleshooting .) On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Is the check result normal?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Check the stop light and the high-mounted stop light for proper function.
Check the stop light and the high-mounted stop light for proper operation when the brake pedal is depressed. Check that the stop light illuminates when the brake pedal is depressed and that it goes out when the brake pedal is released.
OK:
  • When the brake pedal is released: OFF
  • When the brake pedal is depressed: ON
Is the check result normal?
Go to Step 6.
Go to Step 4.
 
STEP 4. Check for stop light switch installation
Refer to GROUP 35A - On-vehicle Service, Brake Pedal Check and Adjustment .
Is the check result normal?
Go to Step 6.
Install the stop light switch correctly (Refer to GROUP 35A - On-vehicle Service, Brake Pedal Check and Adjustment ). Then go to Step 5.
 
STEP 5. Check the stop light switch continuity.
Refer to GROUP 35A - Brake Pedal and Stop light Switch Check .
Is the check result normal?
Go to Step 6.
Replace the stop light switch (Refer to GROUP 35A - Brake Pedal <LHD>, <RHD>). Then go to Step 6.
 
STEP 6. Voltage measurement at the ETACS-ECU connector
(1) Connector check: ETACS-ECU connector, stop light switch connector
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between the stop light switch terminal and body ground.
OK:
  • When the brake pedal is released: 1V or less
  • When the brake pedal is depressed: Approx. system voltage
Is the check result normal?
Go to Step 7.
The power supply circuit may be open or short. Repair the connectors or the wiring harness wires between the ETACS-ECU connector and the stop light switch connector. Then go to Step 7.
 
STEP 7. Diagnostic trouble code recheck
Check again if the diagnostic trouble code is stored.
(1) Erase the stored diagnostic trouble code.
(2) Ignition switch: "LOCK" (OFF)
(3) Ignition switch: "ON"
Is diagnostic trouble code No. C1340 stored?
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to .)
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).