why 1991 Lexus ls400 dash light goes off when headlights go on?

Asked by Aug 05, 2014 at 12:32 PM about the 1991 Lexus LS 400

Question type: Maintenance & Repair

My 1991lexus ls400 dash lights turn off when I turn my headlights on. When I turn off the
headlights, my dash lights go back on. Any advise would be greatly appreciated.

2 Answers


Its the cluster panel. Need to replace.

2 of 2 people found this helpful.

I have a '91 Lexus LS 400. When I turn on the headlights, the transmission drops into low range. I logged onto ASK HOW and talked to a 27 year Lexus Electrical Mechanic. She said the lighting circuits are wired through the transmission backup light circuit. She said I would have to replace the 2 complete taillight modules in the Trunk Lid. I removed both one at a time and had them bench tested. They both tested good. So, to fix my problem temporarily, I removed the bulbs from the taillight modules in the Trunk Lid only and it fixed the problem. When I get time I am going to rewire that circuit. Hope this helps.

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