brake dash light....again.

[Coop15]

brake dash light stays on all the time. I have disconnected the wire from the proportioning valve, and checked the emergency brake switch. What else could there be???

[Wesdog]

What year FSJ?

[Wesdog]

Here's the electrical diagram from a 1990 factory manual. There are 3 ways the light normally gets turned on.
1. Parking brake switch when parking brake is set.
2. Brake warning switch when there is an imbalance between the front/rear brakes.
3. Ignition switch in START position as a check bulb function.

There could be a short to chassis in the wiring that would turn on the light. There could be a problem with the ignition switch.

You could disconnect the wire at the parking brake and use a test light to determine if voltage is present. Same thing at the brake warning switch. If the warning light is ON and both the parking brake and brake warning switches are disconnected then there is a problem with the ignition switch circuit or a short to ground in the harness.

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/90brakelight.jpg

Wesdog

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/wesdog_avitar1.jpg