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.
Inspection Procedure
- INSPECT STOP FUSE
- Remove the STOP fuse from the main body ECU (instrument panel junction block).
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Condition Specified Condition STOP (10 A) fuse Always Below 1 Ω
NG: REPLACE STOP FUSE
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OK: Go to next step
- CHECK STOP LIGHT OPERATION
- Install the STOP fuse.
- Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.
OK
ILLUMINATION CONDITION REFERENCE CHARTCondition Illumination Condition Brake pedal depressed ON Brake pedal released OFF
NG: GO TO STEP 7
OK: Go to next step
- INSPECT SKID CONTROL ECU (STP TERMINAL)
- Disconnect the skid control ECU connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Switch Condition Specified Condition A51-28 (STP) - Body ground Stop light switch ON (Brake pedal depressed) 8 to 14 V A51-28 (STP) - Body ground Stop light switch OFF (Brake pedal released) Below 1.5 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)
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OK: Go to next step
- INSPECT SKID CONTROL ECU (IG1 TERMINAL)
- Turn the ignition switch to ON.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Switch Condition Specified Condition A51-34 (IG1) - Body ground Ignition switch ON 11 to 14 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)
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OK: Go to next step
- INSPECT SKID CONTROL ECU (GND1 TERMINAL)
- Turn the ignition switch off.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Condition Specified Condition A51-1 (GND1) - Body ground Always Below 1 Ω
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: Go to next step
- RECONFIRM DTC
- Reconnect the skid control ECU connector.
- Clear the DTCs (See DTC CHECK / CLEAR ).
- Start the engine.
- Depress the brake pedal several times to test the stop light circuit.
- Check if the same DTC is recorded (See
DTC CHECK / CLEAR ).
Result
RESULT CHARTResult 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 (See PROBLEM SYMPTOMS TABLE ).
B: REPLACE BRAKE ACTUATOR ASSEMBLY (See REMOVAL )
A: CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) (See DIAGNOSIS SYSTEM )
- INSPECT STOP LIGHT SWITCH (POWER SOURCE TERMINAL)
- Disconnect the stop light switch connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Condition Specified Condition A1-2 - Body ground Always 11 to 14 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
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OK: Go to next step
- INSPECT STOP LIGHT SWITCH
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester 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 (See STOP LIGHT SWITCH )
- Measure the resistance according to the value(s) in the table below.
- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH)
- Disconnect the skid control ECU connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Condition Specified Condition A51-28 (STP) - A1-1 Always Below 1 Ω
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: Go to next step
- RECONFIRM DTC
- Reconnect the skid control ECU connector and the stop light switch connector.
- Clear the DTCs (See DTC CHECK / CLEAR ).
- Start the engine.
- Depress the brake pedal several times to test the stop light circuit.
- Check if the same DTC is recorded (See
DTC CHECK / CLEAR ).
Result
RESULT CHARTResult 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 (See PROBLEM SYMPTOMS TABLE ).
B: REPLACE BRAKE ACTUATOR ASSEMBLY (See REMOVAL )
A: INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) (See OPERATION CHECK )
NO RELATED
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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.