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.
1993 Lexus SC 400FACTORY OEM SERVICE PROCEDURE
TRAC Motor Relay
- Remove TRAC motor relay from relay box No. 2. Measure voltage between terminal No. 1 of relay box No. 2 and body ground. Ensure 10-14 volts is present. Check and repair harness or connector, if 10-14 volts is not present.
- Check continuity between terminal No. 2 of relay box No. 2 and terminal MTT of ABS/TRAC ECU. Also check continuity between terminals BTM and MTT of TRAC pump motor. If readings are not 4-6 ohms, repair or replace harness or TRAC pump motor. See Figure.
- Remove TRAC motor relay from relay box No. 6. Measure voltage between terminal No. 1 of relay box No. 6 and body ground. Ensure 10-14 volts is present. Check and repair harness or connector, if 10-14 volts is not present.
- Check continuity between terminal No. 2 of relay box No. 6 and terminal MTT of ABS/TRAC ECU. Also check continuity between terminals BTM and MTT of TRAC pump motor. If readings are not 4-6 ohms, repair or replace harness or TRAC pump motor. See Figure.
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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