Code No.C1340: Open circuit abnormality of stop lamp switch




caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Diagnose the CAN bus lines before the diagnosis codes (Refer to GROUP 54C, CAN bus-line diagnostic flow ).

OPERATION



  • ABS-ECU monitors whether the stop lamp switch is "ON" or "OFF."

DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES




  • Malfunction of the stop lamp switch
  • Damaged wiring harness or connector
  • Malfunction of the hydraulic unit assembly (integrated with ABS-ECU)

DIAGNOSIS

STEP 1. M.U.T.-III CAN bus diagnostics.


caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

Go to Step 3.

Repair the CAN bus line (Refer to GROUP 54C, CAN bus line Diagnostic flow ). Then go to Step 2.

STEP 2. Check whether the diagnosis code is reset.


caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1340 set?

Go to Step 3.

The procedure is complete.

STEP 3. Operation check of stop lamp
(1)Turn the ignition switch to the "ON" position.
(2)Check the operation of the stop lamp when the brake pedal is operated.
OK:

    Brake pedal depressed: ON
    Brake pedal released: OFF

Q. Is the check result normal?
Go to Step 5.
Go to Step 4.

STEP 4. Check of stop lamp switch
Refer to GROUP 35A, Brake pedal Inspection .

Q. Is the check result normal?
Go to Step 6.
Replace it. Then go to Step 8.

STEP 5. Voltage measurement at ABS-ECU connector A-01.

(1)Disconnect the connector A-01, and connect special tool ABS check harness (MB991952) to the wiring harness-side connector.
note Do not connect special tool ABS check harness (MB991952) to the ABS-ECU.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal 3 and terminal 11 or 33.
OK:

    Brake pedal depressed: System voltage
    Brake pedal released: 1 V or less

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

STEP 6. Check ABS-ECU connector A-01, stop lamp switch connector C-114, junction connector C-10 and intermediate connector C-13 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

An open or short circuit may be present between the stop lamp switch and ABS-ECU. Repair the wiring harness between ABS-ECU connector A-01 terminal 3 and stop lamp switch connector C-114. Then go to Step 8.

Repair or replace the damaged component(s). Then go to Step 8.

STEP 7. Check whether the diagnosis code is reset.


Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1340 set?

Replace the hydraulic unit assembly (integrated with ABS-ECU). Then go to Step 8.

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 8. Check whether the diagnosis code is reset.


Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.C1340 set?

Go to Step 1.

The procedure is complete.