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 LS 400FACTORY OEM SERVICE PROCEDURE
Inspection (Using An Ammeter With A Current-Measuring Probe)
- Remove the master switch with connector connected.
- Attach a current-measuring probe to terminal 9, of the wire harness. See Fig 1.
- Turn ignition switch ON and set the power window switch in the down position.
- As the window goes down, check that the current flow is approximately 7 amperes.
- Check that the current increases approximately 14.5 amperes or more when the window stops going down.
NOTE:
The circuit breaker opens some 4-40 seconds after the window stops going down, so that check must be made before the circuit breaker operates.
If operation is not as specified, replace the master switch. See POWER WINDOW MASTER SWITCH .
Factory Service Tools
Use the Manual With the Right Hardware
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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.