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.
1994 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Speedometer System Test
WARNING:
To avoid electric shock when servicing instrument cluster, read SPECIAL WARNING under DESCRIPTION & OPERATION.
- Check VSS. See VEHICLE SPEED SENSOR (VSS) TEST under COMPONENT TESTING. If VSS is okay, remove instrument cluster. Remove cover and power source unit from back of instrument cluster for access to circuit plate. Check for faulty circuit plate.
- If circuit plate is okay, install power source unit. DO NOT install rear cover. Reconnect instrument cluster connectors. Raise and support vehicle with rear wheels off of ground. Turn ignition on.
- At power source unit connector "R", connect voltmeter between terminals No. 10 (+) and 12 (-). See Figure. Rotate drive shaft. If voltage alternates between about zero and 9 or more volts for each revolution of drive shaft, replace speedometer. If voltage does not alternate between about zero and 9 or more volts, replace power source unit.
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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