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.
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HOMESERVICE MANUALSLEXUS1999RX 300 AWD V6-3.0L (1MZ-FE)REPAIR AND DIAGNOSISCRUISE CONTROLBRAKE SWITCH (CRUISE CONTROL)TESTING AND INSPECTIONCRUISE CONTROL SYSTEM
1999 Lexus RX 300 AWD V6-3.0L (1MZ-FE)
Cruise Control System
1999 Lexus RX 300 AWD V6-3.0L (1MZ-FE)SECTION Cruise Control System
CIRCUIT DESCRIPTION
When the brake pedal is depressed, the stop light switch sends a signal to the ECU. When the ECU receives this signal, it cancels the cruise control.
A fail-safe function is provided so that CANCEL functions normally, even if there is a malfunction in the stop light signal circuit.
The cancel conditions are: Battery positive voltage at terminal STP- When the brake is ON, battery positive voltage normally is applied through the STOP fuse and stop light switch to terminal STP- of the ECU, and the ECU turns the cruise control off.
If the harness connected to terminal STP- has an open circuit, terminal STP- will have battery positive voltage and the cruise control will be turned off.
Also, when the brake is ON, the magnetic clutch circuit is cut mechanically by the stop light switch, turning the cruise control OFF. (See for operation of the magnetic clutch)
WIRING DIAGRAM
INSPECTION PROCEDURE
When the brake pedal is depressed, the stop light switch sends a signal to the ECU. When the ECU receives this signal, it cancels the cruise control.
A fail-safe function is provided so that CANCEL functions normally, even if there is a malfunction in the stop light signal circuit.
The cancel conditions are: Battery positive voltage at terminal STP- When the brake is ON, battery positive voltage normally is applied through the STOP fuse and stop light switch to terminal STP- of the ECU, and the ECU turns the cruise control off.
If the harness connected to terminal STP- has an open circuit, terminal STP- will have battery positive voltage and the cruise control will be turned off.
Also, when the brake is ON, the magnetic clutch circuit is cut mechanically by the stop light switch, turning the cruise control OFF. (See for operation of the magnetic clutch)
WIRING DIAGRAM
Step 1:
Step 2:
Step 3:
Step 4:
INSPECTION PROCEDURE
RENDER: 1.0x
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.