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.
2001 Lexus LS 430FACTORY OEM SERVICE PROCEDURE
Power Source Circuit
- Check MPX-B1, MPX-IG and D DOOR fuses. Replace as necessary. If fuses are okay, go to next step.
- Turn ignition on. Measure voltage (backprobe) between driver door ECU connector "B" terminals No. 1 (White/Black wire) and No. 5 (Red/Blue wire). See Fig 1. Battery voltage should be present. Turn ignition off. Disconnect driver door ECU connector. Measure voltage between connector terminals No. 1 (White/Black wire) and No. 4 (Violet/Yellow wire), and between terminals No. 1 (White/Black wire) and No. 6 (Red wire). Battery voltage should be present. If voltages are not to specification, go to next step. If voltages are to specification, check driver door ECU. See BODY CONTROL SYSTEMS - LS430 and MULTIPLEX CONTROL SYSTEMS - LS430 articles.
- If voltages are not to specification, check wiring harness and connectors between master switch and driver door ECU, and between ECU and ground. See WIRING DIAGRAMS . Repair wiring as necessary.
Factory Service Tools
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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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