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
- CHECK STOP LIGHT OPERATION
- Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.
OK
ILLUMINATION CONDITION CHARTCondition Illumination Condition Brake pedal depressed ON Brake pedal released OFF NG: Go to step 6
OK: Go to next step
- Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.
- INSPECT SKID CONTROL ECU (STP TERMINAL)
- Disconnect the skid control ECU connector.
- Inspect the connector case and the terminal for deformation and corrosion.
OK: No deformation or corrosion.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition A15-28 (STP) - Body ground Stop light switch ON (Brake pedal depressed) 8 to 14 V A15-28 (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
VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition A15-34 (IG1) - Body ground Ignition switch ON 11 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: Go to next step
- INSPECT SKID CONTROL ECU (GND TERMINAL)
- Turn the ignition switch off.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
RESISTANCE SPECIFICATIONTester Connection Condition Specified Condition A15-1 (GND1) - Body ground Always Below 1 Ω NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: Go to next step
- RECONFIRM DTC
- Reconnect the skid control ECU connector.
- Clear the DTC (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 not output A DTC 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 CHECK FOR INTERMITTENT PROBLEMS )
- INSPECT STOP LIGHT SWITCH (POWER SOURCE TERMINAL)
- Disconnect the stop light switch connector.
- Inspect the connector case and the terminal for deformation and corrosion.
OK: No deformation or corrosion.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
VOLTAGE SPECIFICATIONTester Connection Condition Specified Condition A13-2 - Body ground Always 11 to 14 V NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: Go to next step
- INSPECT STOP LIGHT SWITCH
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
RESISTANCE SPECIFICATIONTester 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 REMOVAL )
OK: Go to next step
- 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
RESISTANCE SPECIFICATIONTester Connection Condition Specified Condition A15-28 (STP) - A13-1 Always Below 1 Ω A15-28 (STP) - Body ground Always 10 kΩ or higher 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 DTC (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 not output A DTC 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 LIGHTING SYSTEM (STOP LIGHT SWITCH CIRCUIT) (See TERMINALS OF ECU )
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.