Parking brake warning light

[Louis Schuhler]

The parking brake warning light does not light on my 99 XLT 3.0 auto when I apply the brake. I replaced the bulb in the cluster (I had illumination bulbs that were burnt out so I replaced the Brake warning bulb while I had the cluster out) and still no light. The plunger switch on the parking brake pedal moves in and out when I depress the pedal. There seems to be only one wire on the switch. What should be the reading on the wire from the switch, is it ohms, 12 volts, continunity to ground, etc.? What reading would indicate the switch is bad? Can I jumper the wire off the switch to light the warning bulb? Any insight would be appreciated.

 

[shadetree]

The switch supplies ground to the circuit. I do not have a schmatic for this particular curcuit, but with the e brake not engaged, you will read 12vdc on the wire, ignition on. When the brake is engaged, the 12v will go away as it is grounded out. No 12v, you have a problem further up the line.

You can use an ohmmeter, or continuity tester to check and make sure the switch is making a good contact to ground. Find a good ground in the truck with one end of the light/meter, and touch the other end to the wire on the switch, then press the e brake, and the light should light if the ground connection on the switch is good.

Having said all this, as I said, I don't have a schematic. Many of these circuits go thru the GEM module, and this circuit may also, so my diagnostic method may not work, but you can try.shady