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.
1990 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Traction Control System
- Description & Operation
- Bleeding Brake System
- Trouble Shooting
- Self-Diagnostic System
- Diagnostic Charts
- Code 11 & 12: TRAC Brake Main Relay Circuit
- Code 13, 14 TRAC Throttle Relay Circuit
- Code 15, 16 & 17: Pressure Switch Circuit
- Code 19: Fluid Leakage In Actuators Or Tubing
- Code 21, 22 & 23: TRAC Brake Actuator Solenoid Circuit
- Code 24: TRAC Sub-Throttle Actuator Circuit
- Code 25, 26 & 27: TRAC Sub-Throttle Valve
- Code 44: Ne Signal Circuit
- Code 45 & 46: Main Throttle Position Sensor Circuit
- Code 47 & 48: Sub-Throttle Position Sensor Circuit
- Code 49: Engine Communication Circuit
- Code 51: Engine Malfunction Detection Circuit
- Code 52: Brake Fluid Level Warning Switch Circuit
- Code 54 & 55: TRAC Pump Motor Relay Circuit
- Code 56: TRAC Pump Motor Lock Sensor Circuit
- Neutral Start Switch Circuit
- TRAC Off Indicator, TRAC Cut Switch Circuit
- TRAC Indicator Light Circuit
- Diagnostic Circuit
- Component Testing
- Removal & Installation
- Overhaul
- Adjustments
- Specifications
- Wiring Diagrams
Factory Service Tools
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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