Code No.C1346:
Abnormal stop lamp circuit
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- 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 - CAN Bus Diagnostics Table
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASTC-ECU) is replaced, always carry out
the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to ).
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OPERATION
- ASTC-ECU monitors whether the stop lamp is "ON" or "OFF."
- The ASTC-ECU activates the stop lamp relay to illuminate the stop lamps.
- The ASTC-ECU monitors the operating conditions of the stop lamp switch, the stop
lamps and the stop lamp relay.
DIAGNOSIS CODE SET CONDITIONS
- The system cannot recognise the operating condition of the stop lamps.
- When the stop lamp relay is off, the ON/OFF status of the stop lamp switch
does not coincide with the actual stop lamp illumination for at least one second.
- Although the stop lamp relay is on, the stop lamps remain off (do not come on) for
at least one second.
PROBABLE CAUSES
Current trouble
- Malfunction of the stop lamp relay
- The stop lamp switch improperly installed
- Malfunction of the stop lamp switch
- Damaged wiring harness or connector
- Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
Past trouble
- Carry out diagnosis with particular emphasis on the back-up lamp
switch, connector(s) or wiring harness between the back-up lamp 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 ).
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STEP 1. 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 3.
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 Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Erase the diagnosis code.
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Q.
Is diagnosis code No. C1346 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check the stop lamp operation
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Check the stop lamp operation when the brake pedal is depressed. Check that the stop lamp
and high-mount 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: Not illuminate
When the brake pedal is depressed: Illuminate
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Q.
Is the check result normal?
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Go to Step 4.
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Go to Step 7.
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STEP 4. Measure the voltage at the stop lamp relay connector
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(1)Disconnect the connector and measure at the wiring harness side.
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(2)Measure the voltage between the terminal No.1 and earth.
OK: Approximately system voltage
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Q.
Is the check result normal?
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Go to Step 5.
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An open or short circuit to power supply has occurred in the wiring harness between
junction block (fuse 15) and stop lamp relay connector terminal No.1. Repair the relevant fault.
Then go to Step 12.
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STEP 5. Measure the voltage at the stop lamp relay connector
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(1)Disconnect the connector and measure at the wiring harness side.
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(2)Measure the voltage between the terminal No.4 and earth.
OK: Approximately system voltage
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Q.
Is the check result normal?
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Go to Step 6.
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An open or short circuit to power supply has occurred in the wiring harness between
fusible link (5) and stop lamp relay connector terminal No.4. Repair the relevant fault. Then
go to Step 12.
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STEP 6. Check the wiring harness wires between each of the ASTC-ECU
connector terminals (STP2, STP and ASTP) and the stop lamp relay connector terminal.
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Q.
Is the check result normal?
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Go to Step 11.
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Repair the relevant fault. Then go to Step 12.
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STEP 7. Check for stop lamp switch installation
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Check the stop lamp switch installation (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 8.
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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 12.
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STEP 8. Stop lamp switch continuity check
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(1)Check the stop lamp switch connector.
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(2)Refer to GROUP 35A - Inspection, Stop Lamp Switch Check .
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Q.
Is the check result normal?
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Go to Step 9.
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Replace the stop lamp switch (Refer to GROUP 35A - Brake Pedal ).
Then go to Step 12.
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STEP 9. Stop lamp relay check
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Refer to .
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Q.
Is the check result normal?
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Go to Step 10.
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Replace the stop lamp relay. Then go to Step 12.
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STEP 10. Measure the resistance at the stop lamp relay connector
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(1)Remove the high-mounted stop lamp connector, rear combination lamp connector (stop:
LH, RH).
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(2)Check the stop lamp relay connector.
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(3)Disconnect the stop lamp relay and measure at the wiring harness side.
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(4)Measure the resistance between the high-mounted stop lamp connector, rear combination
lamp connector (stop: LH, RH) terminals and stop lamp relay connector terminal, high-mounted
stop lamp connector, rear combination lamp connector (stop: LH, RH) terminals and body earth.
OK: Continuity exists (2 Ω or less).
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Q.
Is the check result normal?
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Go to Step 11.
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The circuit may be open. Repair the wiring harness wires or connectors between
the high-mounted stop lamp connector, rear combination lamp connector (stop: LH, RH) terminals
and stop lamp relay connector terminal, high-mounted stop lamp connector, rear combination lamp
connector (stop: LH, RH) terminals and body earth. Then go to Step 12.
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STEP 11. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "ON" position.
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(3)
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Do not depress the brake pedal while the actuator test is in progress.
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Use the M.U.T.-III to execute actuator test item No.11 "Stop lamp test mode" (refer to
Actuator Test Table ).
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(4)Check if the diagnosis code is set.
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(5)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1346 set?
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Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
Then go to Step 12.
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions ).
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STEP 12. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "ON" position.
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(3)
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Do not depress the brake pedal while the actuator test is in progress.
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Use the M.U.T.-III to execute actuator test item No.11 "Stop lamp test mode" (refer to
Actuator Test Table ).
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(4)Check if the diagnosis code is set.
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(5)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1346 set?
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Return to Step 1.
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The procedure is complete.
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