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 SC 400FACTORY OEM SERVICE PROCEDURE
Memory Set Switch Circuit
- Turn ignition off. Remove tilt and power telescopic ECU with wiring harness connector attached. Turn ignition on. Using a voltmeter, measure voltage by backprobing rear of 18-pin ECU harness connector T10 between terminals No. 11 (Yellow/Green wire) and No. 8 (Blue/Red wire). See Figure. If battery voltage exists with memory set switch off and less than one volt with memory set switch on, go to next test listed in SYMPTOM DIAGNOSIS table under TROUBLE SHOOTING. If voltage is not as specified, go to next step.
- Turn ignition off. Disconnect 4-pin driving position memory and return switch harness connector. Using an ohmmeter, measure resistance between driving position memory and return switch harness connector terminals No. 4 (Red/Yellow wire) and No. 3 (Brown/Black wire). See Fig 1. If resistance is one megohm or more with memory set switch off and continuity exists with memory set switch on, go to next step. If resistance is not as specified, replace driving position memory and return switch and retest system operation.
- Check wiring harness and connectors between tilt and power telescopic ECU and driving position memory and return switch. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, check tilt and power telescopic ECU. See TILT & TELESCOPIC ECU PIN VOLTAGE TESTS under COMPONENT TESTS. Replace tilt and power 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.