How to Fix Strange Dash Lighting & Brake Problems
1990-1994 Lexus LS400

I wasn't really sure what to title this one but I think it works. If your dash lights are performing strangely this may help. It is a repair for an obscure problem where the "light bulb out" light stays on after starting the engine, accompanied by strange behavior when the brake pedal is depressed, i.e. both the reverse/drive lights illuminate, the entire dash lights go out, and the brakes feel coarse and harsh in application.

This is all caused by a simple broken wire(s), the white one in my case, in a group of wires contained in a small harness that routes around the left hinge of the trunk. One or more wires can break over the years by repeated opening and closing of the trunk lid which flexes/stretches the harness.  With one or more broken wires it causes false readings to the computer, which then behaves erratically.

It is easy to solve by detaching the harness clip from the hinge and pulling the harness free to work on it. Then it's simply opening the harness binding carefully, determining which wire is broken, cleaning/stripping the ends and soldering them back together carefully. You may need to use a short piece of similar gauge copper wire if the wires are too short. Then wrapping the soldered part with insulated tape, rewrapping the entire harness group with tape, and reclipping it back into the hinge track. It takes about 20 minutes start to end.

A dealer would probably replace the entire harness for a ridiculous price after charging for "diagnosis" as well. I have done this twice now over the last 2 years.

Tools Needed:

• Wire stripper / crimper
• Soldering iron