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Dash Lights Stay On After Car Is Turned Off

Rob Arnett

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Good Morning Rob...

I'll be interested in finding out what the problem is myself. I used to have the same problem with my 95 SC400 as well. The first time I noticed it was while I was driving to work in the rain. I got to work and someone came in and told me that my alarm was going off. So I went outside to find that the lights on the instrument panel were on as well.

This continued to happen maybe 3 or 4 times after that. The irony is that I never found out what was causing this issue. It's been probably just over a year and some months since I've had any problems.

I'm keeping my fingers crossed. Good luck. I hope you find out what is causing the problem.


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  • 9 months later...


UPDATE SOLVED: See this thread http://us.lexusownersclub.com/forums/index...showtopic=38035

My SC400 95' just got the exact same symptom. I am searching for solutions, before I take it to Lexus Shop.

I also found this posting in the forum about the same problem. A defective key lock is indicated, but not conclusive.

Did you ever figure out what, and where, the real problem was? - I'm desperate! For the moment, only work-around is to disconnect battery. Very humiliating for a Lexus Owner :rolleyes:

Thanks alot for reply!


(Denmark, Northern Europe)

P.S. In Denmark only 3 of this model exists. 1. generation SC was never marketed in Europe (yeah, I know; I'm asking for trouble)

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  • 9 years later...

SOLVED:  (at least for me.)

I have a 95 LS400 Lexus.  Like Lars in Denmark 10 years ago, my dash lights stayed on even with my key out.  I was driving around and pulling the battery cable each time I stopped to avoid draining the battery.  Soo, I did what Lars suggested and checked the plug in the trunk that was once used for a car phone. (Right side in my car.)  Yes indeed, mine was green and corroded.  Water pools in this area of the trunk and can cause wire corrosion.   To fix that issue, I  carefully connected the individual wires to one another thus eliminating the corroded plug.  Be careful when touching with this plug.  The wires are so bad they will fall out of the plug leaving you not knowing which wire goes where.  The colors on each side of the plug are different!  Be careful.  Take pictures!  Important:  My plug fell apart leaving me with no idea how to rebuild the wire connections.  I actually found a wrecking yard that had a 95 LS400, and sold me the plug.  $25. bucks, but my guess is it will be increasingly hard to find one of these plugs if your's falls apart like mine did.  I am attaching 5 photos of the plug I bought.  Hopefully you can see the photos below on this post.  Maybe do one wire at a time with the plug still attached.  This wire is the type that is REALLY hard to solder, so I stripped back some insulation and twisted the wires together, on by one.  Then I soldered the twists and covered each with shrink wrap.  When done, I nylon tie wrapped the bundle up out of any future water.  Suggestion:  Drill a  hold in the bottom of this trunk area so water can't pool in the future.  Also, check to see that the water tube is properly routed out of this area.  This tube (I think) comes from the moon roof so it transfers water any time it rains.  

This DID NOT solve my problem.

I then changed the ignition switch.  This DID NOT solve my problem.

Next I connected the battery cable and saw that the dash lights come on, key out, as expected.  One by one I then pulled fuses to see if one would make the dash lights go out.  Bingo.... ALT-S was the culprit.   There was a short in my ALT-S wiring thus letting 12 volt backwards into the ignition even with the key out.

ALT-S is the wire that senses the voltage for the alternator.  My first thinking was that the diodes in the alternator failed and leaked 12 volt back up ALT-S.  To test this I UNplugged the plug from the back of the alternator and then put the ALT-S fuse back in.  Dash lights came back on, key still out.  So the short was between the plug and the fuse thus eliminating the alternator as the problem.  The short was in the wire, somewhere.  OK, so it determined the culprit wire was white with a blue stripe, so I bypassed it and created a new wire link.  This DID NOT solve my problem.

Solution was a plug I had replaced on the back of the alternator.  (common ebay available pigtail part.)  The original plug gets old and crumbles, so I got the correct pigtail on ebay and had a shop solder it to the existing wires.  The shop F'd this up.  There was a short between shrink wrap of the splices.  The wires were individually shrink wrapped, but the guy took a large shrink wrap and squished the 3 splices together.  Looked good but shorted out in time and backfed 12 volt up the ALT-S wire thus keeping my dash lights lit.

I hope this helps.

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