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 SWITCH OPERATION
- Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.
OK: Stop light switch function is normal.
HINT:
Check the stop light bulb as it may have burned out.
NG: GO TO LIGHTING SYSTEM (STOP LIGHT CIRCUIT) (See STOP LIGHT CIRCUIT )
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 A24 skid control ECU connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
STANDARD VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition A24-7 (STP) - Body ground Stop light switch on (Brake pedal depressed) 8 to 14 V A24-7 (STP) - Body ground Stop light switch off (Brake pedal released) Below 1.5 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to Next Step
- INSPECT SKID CONTROL ECU (STP2 TERMINAL)
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
STANDARD VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition A24-45 (STP2) - Body ground Stop light switch on (Brake pedal depressed) 8 to 14 V A24-45 (STP2) - Body ground Stop light switch off (Brake pedal released) Below 1.5 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to Next Step
- Measure the voltage according to the value(s) in the table below.
- PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY)
- Reconnect the A24 skid control ECU connector.
- Connect the Techstream to the DLC3.
- Turn the engine switch on (IG) and turn the Techstream on.
- Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
ABS/VSC/TRAC
ACTIVE LIST - ABS/VSC/TRACItem Test Part Control Range Diagnostic Note Stop Light Relay BRK LP relay Relay ON/OFF Observe the rear combination light (Does not come on for 5 seconds or more). - Check that "ON" and "OFF" of the stop light can be shown on the rear combination light by the Techstream.
OK: The stop light turns on or off in accordance with the Techstream.
NG: Go to step 6
OK: Go to Next Step
- RECONFIRM DTC
- Clear the DTC (See DTC CHECK/CLEAR ).
- Check if the same DTC is output (See DTC CHECK/CLEAR
).
HINT:
Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.
Result
RESULT REFERENCEResult Proceed to DTC is output A DTC is not output B B: USE SIMULATION METHOD TO CHECK (See HOW TO PROCEED WITH TROUBLESHOOTING )
A: REPLACE MASTER CYLINDER SOLENOID (See DISASSEMBLY )
- INSPECT BRK LP RELAY (POWER SOURCE TERMINAL)
- Remove the BRK LP relay.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
STANDARD VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition 1 - Body ground Engine switch on (IG) 8 to 14 V 5 - Body ground Always 11 to 14 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to Next Step
- INSPECT BRK LP RELAY
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
STANDARD RESISTANCE SPECIFICATIONTester Connection Condition Specified Condition 3 - 4 When battery positive voltage is applied to terminal 1 and battery negative voltage is applied to terminal 2 10 kΩ or higher When battery positive voltage is not applied to terminal 1 and battery negative voltage is not applied to terminal 2 Below 1 Ω 3 - 5 When battery positive voltage is applied to terminal 1 and battery negative voltage is applied to terminal 2 Below 1 Ω When battery positive voltage is not applied to terminal 1 and battery negative voltage is not applied to terminal 2 10 kΩ or higher NG: REPLACE BRK LP RELAY
OK: Go to Next Step
- INSPECT SKID CONTROL ECU (STPO TERMINAL)
- Install the BRK LP relay.
- Disconnect the A24 skid control ECU connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
STANDARD VOLTAGE SPECIFICATIONTester Connection Switch Condition Specified Condition S37-16 (STPO) - Body ground Engine switch on (IG) 11 to 14 V
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to Next Step
- RECONFIRM DTC
- Clear the DTC (See DTC CHECK/CLEAR ).
- Check if the same DTC is output (See DTC CHECK/CLEAR
).
HINT:
Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.
Result
RESULT REFERENCEResult Proceed to DTC is output A DTC is not output B
B: USE SIMULATION METHOD TO CHECK (See HOW TO PROCEED WITH TROUBLESHOOTING )
A: REPLACE MASTER CYLINDER SOLENOID (See DISASSEMBLY )
Use the Manual With the Right Hardware
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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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