DTC C1426: Stop Light Switch OFF Stuck Malfunction [08/2019 - ]: Procedure

1. Turn the engine switch off.
2. Check the brake pedal height and stop light switch installation (Refer to ADJUSTMENT [08/2015 - ] ).

   OK

   The brake pedal height and stop light switch installation are normal.

Result: 

NG 

ADJUST BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION 

(Refer to ADJUSTMENT [08/2015 - ] )

Result: 

OK 

See step  2

1. Check that the all stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

   OK

   Condition	Illumination Condition
   Brake pedal depressed	On
   Brake pedal released	Off

Result: 

NG 

See step  5

Result: 

OK 

See step  3

1. Turn the engine switch off.
2. Connect the Techstream to the DLC3.
3. Turn the engine switch on (IG).
4. Turn the Techstream on.
5. Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.
   ABS/VSC/TRC
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Stop Light SW	Stop light switch/ ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

6. Check that the stop light switch display observed on the Techstream changes according to brake pedal operation.

   OK

   The Techstream displays ON or OFF according to brake pedal operation.

Result: 

NG 

See step  8

Result: 

OK 

See step  4

1. Turn the engine switch off.
2. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2019 - ] ).
3. Start the engine.
4. Depress the brake pedal several times to test the stop light circuit.
5. Check if the same DTC is output (Refer to DTC CHECK / CLEAR [08/2019 - ] ).
   RESULT
   
   

   Result	Proceed to
   DTC C1426 is output	A
   DTC C1426 is not output	B

   HINT: 

   If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

Result: 

A 

USE SIMULATION METHOD TO CHECK 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] )

Result: 

B 

REPLACE MASTER CYLINDER SOLENOID 

(Refer to REMOVAL [08/2015 - ] )

1. Check the stop light switch assembly (Refer to ON-VEHICLE INSPECTION [08/2019 - ] ).

   OK

   The stop light switch assembly is normal.

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY 

(Refer to REMOVAL [08/2015 - ] )

Result: 

OK 

See step  6

Refer to PROCEDURE - Step 8

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT) 

Result: 

OK 

See step  7

1. Reconnect the A6 skid control ECU (master cylinder solenoid) connector.
2. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2019 - ] ).
3. Turn the engine switch off.
4. Start the engine.
5. Depress the brake pedal several times to test the stop light circuit.
6. Check if the same DTC is output (Refer to DTC CHECK / CLEAR [08/2019 - ] ).
   RESULT
   
   

   Result	Proceed to
   DTC C1426 is not output	A
   DTC C1426 is output	B

Result: 

A 

USE SIMULATION METHOD TO CHECK 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] )

Result: 

B 

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] )

Refer to PROCEDURE - Step 8

Result: 

OK 

REPLACE MASTER CYLINDER SOLENOID 

(Refer to REMOVAL [08/2015 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)