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
Sensor Power Source Circuit
- Turn ignition on. Remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Measure voltage by backprobing rear of terminal No. 12 (Black/Blue wire) with voltmeter positive lead and by backprobing rear of terminal No. 4 (White wire) with negative lead at 22-pin ECU harness connector T9. See Figure. Measure voltage by backprobing rear of terminal No. 13 (White/Red wire) with voltmeter positive lead and by backprobing rear of terminal No. 5 (White/Blue wire) with negative lead at 22-pin ECU harness connector T9. If voltage is not 4.5-5.5 volts for both measurements, go to step 3. If voltage is 4.5-5.5 volts for both measurements, go to next step.
- Check wiring harness and connectors for an open between tilt and telescopic ECU, tilt motor and telescopic motor. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in SYMPTOM DIAGNOSIS table under TROUBLE SHOOTING.
- Check wiring harness and connectors for a short between tilt and telescopic ECU, tilt motor and telescopic motor. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, check tilt and telescopic ECU. See TILT & TELESCOPIC ECU PIN VOLTAGE TESTS under COMPONENT TESTS. Replace tilt and telescopic ECU as necessary and retest system operation.
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.