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.
2000 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Master Switch Circuit
- Using scan tool, check for body control ECU DTCs. If DTC B1221 is present, go to next step. If DTC B1221 is not present, check body control ECU. See BODY CONTROL SYSTEMS - LS400 article.
- Check master switch. See MASTER SWITCH under COMPONENT TESTS. Repair as necessary. If master switch is okay, go to next step.
- Check wiring harness and connectors between master switch and driver door ECU. See WIRING DIAGRAMS . Repair as necessary. If wiring harness and connectors are okay, perform check for next fault listed under appropriate symptom. See TROUBLE SHOOTING .
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.