DTC C1A4B: Stop Light Relay Circuit: Procedure

CHECK DTC OUTPUT (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)
1. Check DTC for electronically controlled brake system. Refer to DTC CHECK / CLEAR .
  OK
  
  Electronically controlled brake system DTC is not output.
NG → See step 5

OK: Go to next step
REPLACE BRAKE BOOSTER WITH MASTER CYLINDER
1. Replace the brake booster with master cylinder (skid control ECU). Refer to REMOVAL .
NEXT: Go to next step
CHECK DTC OUTPUT (PRE-COLLISION SYSTEM)
1. Using the Techstream, enter the following menus: Body Electrical / Pre-Collision 2 / Trouble Codes.
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .
3. Check for DTCs.
  OK
  
  DTC U0122 is not output.
NG → See step 6

OK → See step 4
REPLACE DRIVING SUPPORT ECU. Refer to REMOVAL
GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM. Refer to DIAGNOSTIC TROUBLE CODE CHART
GO TO CAN COMMUNICATION SYSTEM. Refer to HOW TO PROCEED WITH TROUBLESHOOTING