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lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 9974
Experience:  Master Certified with lexus, 8 years experience with Lexus
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2004 Lexus LS430 Left high beam headlight works perfectly.

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2004 Lexus LS430 Left high beam headlight works perfectly. Right side, no high beam and no lower power running light. All fuses appear to be good. The headlight relay "clicks", the under-hood fuses are all good. Exchanged the bulb....even swapped with the opposite side....still doesn't work. Help please!!

Hello and thank you for using just answer!

Is this a HID or a halogen headlamp system?

Did you check all 4 fuses?

Customer: replied 7 years ago.
Peter, the bulb is a Sylvania 9005 HB3U (don't know which type of bulb that is). I checked two fuses in the engine compartment that are labeled as headlight fuses (number 71 for low beams). I also checked one fuse #86 that says "headlights high beam". That is only 3 fuses that I could find in my manual. I hope you can help!! Thanks, Robert
Sorry you are right, just 3 fuses.
So BOTH low beams work just no high beam on one side right?
Do you have a volt meter or test light?
Customer: replied 7 years ago.
I have both volt meter and test light. Test light will not work on the right side when connected to the battery ground and either of the leads to the socket.
Use the volt meter and measure voltage on the power side wire, then on the ground side check continuity to ground and tell me what you find. The white wire with a black stripe is the ground wire.
Customer: replied 7 years ago.

White/blk to ground checked out OK. Voltage between ground wire and hot side of the plug came out to 8.34 volts...way low. That was with the high beams "on". Also, this side does not have the running light working like the driver's side.


From what you are telling me here and what I am reading on the factory wiring diagram it appears the headlamp controller in the lamp is malfunctioning.
Customer: replied 7 years ago.
don't understand...where is the headlamp controller? You said, "controller in the lamp". Is it part of the car, or part of the lamp? thanks
There is an "ecu" or "controller" inside the headlamp, to access this requires removing the front bumper so you can remove the headlamp and remove the access panel on the bottom of the lamp, the next step here is exposing the controller to take a input and output voltage reading to confirm this has failed. Sorry for bad news....this is not too uncommon on this car.
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