Chrysler Repair: 1993 Chrysler Lebaron Brake Warning Lamp, 1993 chrysler lebaron, chrysler lebaron

Question
I am troubleshooting a problem where the brake light stays on, but the problem might be easier if I knew how the two switches (emergency brake and pressure differential) work. Do these switches activate the warning lamp by closing a circuit to ground or opening it?  I have found that even when the wire is disconnected from the pressure differential connector, the light remains on.  Does the sensor automatically reset after line pressure in both hydraulic systems is normalized or does it have to be reset?

Answer
Hi Steven,
The brake warning lamp is actuated by 4 different means: ground at the parking brake mechanism, grounding at the ABS module (if equipped), grounding by the brake proportional valve, and grounding at the ignition switch when in the 'start' position. Any one of those 4 switches will turn on the light. The light has 12v on and is illuminated by the other end of the filament being grounded. The proportioning valve grounding set will self-reset once the pressure differential is corrected and pressure is applied to the brake system by the master cylinder. Any one of those gray/black wires could have a short to ground.
Roland
I just saw your question in the 'pool' to which it had been referred after 'shopteacher' dropped out of the service, apparently.