Ls400 '93 - Turn On Lights, Transmission Fails

[gforce454]

Greetings all, I'm new to the forum. I have a '93 Lexus ls 400. My issue is that when I turn on my headlights, my transmission fails to operate properly and I have to pull over. Once, I turned off the lights everything operates fine. Any suggestions on how to handle this. Any guidance would be greatly appreciated. Thank you in advance for your help.

Gary

[SRK]

Sounds like the headlights are finding a ground path different from the intended one. I don't know where it is, but it would be a start to find the ground wire for the headlights and check that it is secure.

[1990LS400]

If you have not done it already, check for broken wires at the left trunk hinge -- absolutely the #1 cause of erratic transmission shifting on the 90-94 LS400. Unwrap the insulation and wiggle each wire to determine if the wire core has broken since a wire core can break without the insulation breaking. If any wires are broken, splice in short lengths of wire -- soldering is best but you can get by for a while with just twisting the connected wires together and wrapping them with tape.

The problem could be caused by something else but check the trunk hinge wires first -- the problem eventually effects ALL 90-94 LS400's.

[steve2006]

This well known problem.

http://www.lexls.com/tutorials/lighting/bulbout.html