Code No.C1346:
Abnormal stop lamp circuit
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- 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
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- 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
- 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
- Blown stop lamp bulbs
- 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 stop lamp switch,
connector(s) or wiring harness between the stop lamp switch and ASTC-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. 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 data list
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Check the data list in the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
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- Item No.108: Stop lamp switch
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Q.
Is the check result normal?
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Go to Step 3.
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Diagnose the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
Then go to Step 9.
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STEP 3. M.U.T.-III actuator test
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Execute the actuator test below to check the stop lamps for proper operation (Refer to ).
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- Item No.11: Stop lamp test mode
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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 4.
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STEP 4. Measure the voltage at the ASTC-ECU connector (ASTP terminal)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Check the voltage between the ASTC-ECU connector ASTP terminal and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 5.
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STEP 5. Check of short to earth, and open circuit in ASTP line between
ASTC-ECU connector and stop lamp relay connector. Check of short to earth, and open circuit
in power supply line between fusible link and stop lamp relay connector.
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(1)Disconnect the ASTC-ECU connector and stop lamp relay connector, and measure at
the wiring harness side.
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(2)Measure the resistance between the ASTC-ECU connector ASTP terminal and the stop
lamp relay connector terminal No.7.
OK: Continuity exists (2 Ω or less)
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(3)Measure the resistance between the ASTC-ECU connector ASTP terminal and body earth.
OK: No continuity (1 kΩ or more)
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(4)Check the voltage between the stop lamp relay connector terminal No. 4 and body
earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 6.
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Repair the connector(s) or wiring harness. Then go to Step 9.
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STEP 6. Check of open circuit in earth line between the stop lamp
relay connector and body earth.
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(1)Disconnect the stop lamp relay connector, and measure at the wiring harness side.
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(2)Measure the resistance between the stop lamp relay connector terminal No.6 and
body earth.
OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
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Replace the stop lamp relay (Refer to GROUP 35A - On-vehicle Service ).
Then go to Step 9.
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Repair the connector(s) or wiring harness. Then go to Step 9.
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STEP 7. Check of open circuit in STP line between the ASTC-ECU connector
and the stop lamp relay connector.
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(1)Disconnect the ASTC-ECU connector, and measure at the wiring harness side.
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(2)Depress the brake pedal.
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(3)Check the voltage between the ASTC-ECU connector STP terminal and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 8.
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Repair the connector(s) or wiring harness. Then go to Step 9.
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STEP 8. 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 set diagnosis code.
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(2)Ignition switch: "LOCK" (OFF)
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(4)Execute the actuator test (Refer to ).
- Item No.11: Stop lamp test mode
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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 ).
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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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STEP 9. 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 set diagnosis code.
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(2)Ignition switch: "LOCK" (OFF)
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(4)Execute the actuator test (Refer to ).
- Item No.11: Stop lamp test mode
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Q.
Is diagnosis code No. C1346 set?
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Return to Step 1.
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This diagnosis is complete.
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