Code No. C1340: Stop lamp switch
caution |
- When more than one stop lamp bulb are blown, diagnosis code No. C1340 may be set.
- If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - Troubleshooting
).
- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit assembly (integrated with ASTC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G sensor (Refer to
).
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OPERATION
The ASTC-ECU monitors the ON/OFF signals from the stop lamp switch and the pressure sensor (incorporated in the hydraulic unit).
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set in the following case.
- When the vehicle has been driven for a long time with the stop lamp switch turned ON.
- The vehicle is being stopped although the stop lamp switch remains off.
PROBABLE CAUSES
- Blown stop lamp bulbs
- The CAN bus line is defective.
- Improper adjustment of stop lamp switch installation position
- Malfunction of stop lamp switch
- Malfunction of ETACS-ECU
- Damaged harness wires and connectors
- Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
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STEP 1. Check the stop lamp and the high-mounted stop lamp for proper function.
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Check the stop lamp and the high-mounted stop lamp for proper operation when the brake pedal is depressed.
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OK:
When the brake pedal is released: OFF When the brake pedal is depressed: ON
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Q.
Is the check result normal?
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Go to Step 2.
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Diagnose the rear combination lamps (Refer to GROUP 54A - Rear Combination lamp ).
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STEP 2. M.U.T.-III CAN bus diagnosis
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 3.
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STEP 3. Diagnosis code recheck after resetting CAN bus lines
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Q.
Is the check result normal?
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Go to Step 4.
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This diagnosis is complete.
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STEP 4. Check the stop lamp and the high-mounted stop lamp for proper function.
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Check the stop lamp and the high-mounted stop lamp for proper operation when the brake pedal is depressed. Check that the stop lamp illuminates when the brake pedal is depressed and that it goes out when the brake pedal is released.
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OK:
When the brake pedal is released: OFF When the brake pedal is depressed: ON
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Q.
Is the check result normal?
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Go to Step 7.
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Go to Step 5.
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STEP 5. Check for stop lamp switch installation
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Refer to GROUP 35A - On-vehicle Service, Brake Pedal Check and Adjustment .
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Q.
Is the check result normal?
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Go to Step 7.
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Install the stop lamp switch correctly (Refer to GROUP 35A - On-vehicle Service, Brake Pedal Check and Adjustment ). Then go to Step 6.
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STEP 6. Check the stop lamp switch continuity.
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Refer to GROUP 35A - Brake Pedal and Stop Lamp Switch Check .
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Q.
Is the check result normal?
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Go to Step 7.
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Replace the stop lamp switch (Refer to GROUP 35A - Brake Pedal ). Then go to Step 7.
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STEP 7. Voltage measurement at the ETACS-ECU connector
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(1)Connector check: ETACS-ECU connector, stop lamp switch connector
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(2)Turn the ignition switch to the "ON" position.
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(3)Measure the voltage between the stop lamp switch terminal and body earth. OK:
When the brake pedal is released: 1V or less When the brake pedal is depressed: Approx. system voltage
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Q.
Is the check result normal?
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Go to Step 8.
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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 lamp switch connector. Then go to Step 8.
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STEP 8. Diagnosis code recheck
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Check again if the diagnosis code is set.
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(1)Erase the set diagnosis code.
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(2)Ignition switch: "LOCK" (OFF)
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Q.
Is diagnosis code No. C1340 set?
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Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
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