Code No. C1340: Stop lamp switch malfunction <short circuit (short to power supply)>
caution
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 .).
Before replacing the ECU, ensure that the communication circuit is normal.
OPERATION
ABS-ECU monitors whether the stop lamp switch is "ON" or "OFF."
DIAGNOSIS CODE SET CONDITION
This diagnosis code will be set if the vehicle speed is 15 km/h or more with the stop lamp switch "ON" continuously for 15 minutes or more.
PROBABLE CAUSES
Improper adjustment of stop lamp switch installation position
Malfunction of the stop lamp switch
Damaged wiring harness and connectors
Malfunction of the ABS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines. (Refer to GROUP 54C -
CAN Bus Diagnostics Table .). On completion, go to Step 2.
STEP 2. Diagnosis code recheck after resetting CAN bus lines
Erase the diagnosis code.
Q.
Is diagnosis code No.C1340 set?
Go to Step 3.
This diagnosis is complete.
STEP 3. Stop lamp and high-mount stop lamp operation check
Check the stop lamp and high-mount stop lamp operation when the brake pedal is depressed. Check that the stop lamp and high-mount stop lamp illuminate 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
Refer to GROUP 35A -
Brake Pedal -
Stop Lamp Switch Check .
Q.
Is the check result normal?
Go to Step 6.
Install the stop lamp switch correctly (Refer to GROUP 35A -
Brake Pedal -
Stop Lamp Switch Check .). Then go to Step 11.
STEP 6. Stop lamp switch continuity check
(1)Remove the stop lamp switch (Refer to GROUP 35A -
Brake Pedal .).
(2)Connect the circuit tester (Ω
range) to the stop lamp switch connector terminals No.1 and No.2. (3)When no continuity is detected with the plunger pressed from the edge of the outer case by the dimension shown in the figure and when continuity is detected with the plunger released, the stop lamp switch is in good condition.
Q.
Is the check result normal?
Go to Step 7.
Replace the stop lamp switch (Refer to GROUP 35A -
Brake Pedal .). Then go to Step 11.
STEP 8. Voltage measurement at A-01 ABS-ECU connector.
(1)Disconnect the A-01 ABS-ECU connector.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal No.27 and body earth. OK: 1 V or less
Q.
Is the check result normal?
Go to Step 9.
A short to power supply has occurred in the wiring harness between A-01 ABS-ECU connector terminal No.27, C-10 joint connector terminal No.1 and C-13 intermediate connector terminal No.2, therefore, repair it.Then go to Step 11.
STEP 9. Voltage measurement at C-114 stop lamp switch connector.
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Go to Step 3.
Repair the CAN bus lines. (Refer to GROUP 54C -
CAN Bus Diagnostics Table 
.). On completion, go to Step 2.)