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.
1990 Lexus ES 250 AutomaticFACTORY OEM SERVICE PROCEDURE
Theft Deterrent System Starter Cut System Circuit
- If starter does not operate even after theft system has been deactivated, use key to turn front door lock to unlock position. Check starter for operation. If starter still does not operate, go to next step. Theft deterrent ECU is located under dashboard, above glove box.
- Disconnect theft deterrent ECU connectors. Turn ignition switch to START position. Ensure shift lever is in N or P, or clutch pedal is depressed. Using a DVOM, check for battery voltage between theft deterrent ECU connector terminal No. 1 of 18-pin connector and ground. See Fig 1.
- If battery voltage is not present, repair short or open in starter relay circuit. If battery voltage is present, replace theft deterrent ECU and retest system.
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.