2010 Lexus LS 460L AWDFACTORY OEM SERVICE PROCEDURE

DTC C1249/49: Open in Stop Light Switch Circuit: Procedure

  1. INSPECT FUSE (STOP) 
    1. Remove the STOP fuse from the main body ECU.
    2. Measure the resistance of the fuse.

      Standard resistance

      Tester Connection Condition Specified Condition
      STOP fuse Always Below 1 Ω

    NG → REPLACE FUSE 

    OK: Go to next step 

  2. READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Data List mode on the Techstream.
      ABS/VSC/TRAC

      Tester Display Measurement Item/Range Normal Condition
      Stop Light SW Stop light switch / ON or OFF ON: Brake pedal depressed
      OFF: Brake pedal released
    4. Check that the stop light observed on the Techstream changes when the brake pedal is depressed.

      OK

      When the brake pedal is depressed, the Techstream displays "ON".

    OK → See step   8 

    NG: Go to next step 

  3. CHECK TERMINAL VOLTAGE (STOP LIGHT SWITCH) 
    1. Disconnect the A35 switch connector.
      Fig 1: Identifying A35 Switch Connector Terminals
      GTY110842Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage

      Tester Connection Condition Specified Condition
      A35-2 - Body ground Always 11 to 14 V

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. INSPECT STOP LIGHT SWITCH 
    1. Disconnect the stop light switch connector.
      Fig 2: Inspecting Stop Light Switch
      GTY132220Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin free Below 1 Ω
      1 - 2 Switch pin pushed in 10 kΩ or higher

    NG → REPLACE STOP LIGHT SWITCH 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH) 
    1. Disconnect the A21 ECU connector.
    2. Disconnect the A35 switch connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      A21-25 (STP) - A35-1 Always Below 1 Ω
      A21-25 (STP) - Body ground Always 2 kΩ or lower

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BODY GROUND) 
    1. Disconnect the A19 and A21 ECU connectors.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection Condition Specified Condition
      A19-1 (GND) - Body ground Always Below 1 Ω
      A21-1 (GND4) - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  7. RECONFIRM DTC 
    1. Clear the DTC. Refer toDTC CHECK / CLEAR .
    2. Start the engine.
    3. Depress the brake pedal several times to test the stop light circuit.
    4. Check if the same DTC is recorded. Refer toDTC CHECK / CLEAR .

      HINT: 

      Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

      RESULT

      Result Proceed to
      DTC (C1249/49) is not output A
      DTC (C1249/49) is output B

      HINT: 

      If troubleshooting has been carried out according to the "PROBLEM SYMPTOMS TABLE", refer back to the table and proceed to the next step. Refer toPROBLEM SYMPTOMS TABLE .

    B → See step   9 

    A → END 

  8. GO TO LIGHTING SYSTEM. Refer to HOW TO PROCEED WITH TROUBLESHOOTING 
  9. REPLACE SKID CONTROL ECU. Refer to REMOVAL 
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.