Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC C1249/49: Open in Stop Light Switch Circuit: Procedure
- INSPECT FUSE (STOP)
- Remove the STOP fuse from the main body ECU.
- 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
- READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH)
- Connect the Techstream to the DLC3.
- Turn the engine switch on (IG).
- 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 - 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
- CHECK TERMINAL VOLTAGE (STOP LIGHT SWITCH)
- Disconnect the A35 switch connector.
- 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
- INSPECT STOP LIGHT SWITCH
- Disconnect the stop light switch connector.
- 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
- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH)
- Disconnect the A21 ECU connector.
- Disconnect the A35 switch connector.
- 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
- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BODY GROUND)
- Disconnect the A19 and A21 ECU connectors.
- 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
- RECONFIRM DTC
- Clear the DTC. Refer toDTC CHECK / CLEAR .
- Start the engine.
- Depress the brake pedal several times to test the stop light circuit.
- 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.
RESULTResult 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
- GO TO LIGHTING SYSTEM. Refer to HOW TO PROCEED WITH TROUBLESHOOTING
- REPLACE SKID CONTROL ECU. Refer to REMOVAL
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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.
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