No brake lights on an '85 T-bird. I've checked the brake light fuse; it's good.?

Question

I've bypassed the brake light switch that's attached to the upper portion of the brake pedal by unplugging the wires going to it and touching them together and I've also ohmed-out the switch and believe the switch to be good. I've replaced all of the brake light bulbs and still no brake lights. I have tested the fuse box at the brake light fuse location and found that the fuse in the fuse box isn't getting the volts that it normally does whether the engine is running or not. I've replaced all of the brake light bulbs also. Why isn't the fusebox getting the required electricity?

Answer 1

If the voltage reading is less than battery voltage, it is possible that you have a loose connection or a damaged wire or a fusible link problem. But this is less likely. Make sure your voltmeter is properly grounded by checking a know good circuit. When diagnosing 12 volt lighting issues it is often better to use a simple test light. By the way, the voltage on a brake light circuit is the same with the ignition on or off. Something often overlooked in diagnosing a brake light problem is the turn signal switch. On older domestic vehicles like yours the turn signals in the rear share the same wiring as the brake lights and therefore the circuit passes through the turnsignal switch after leaving the brake light switch. Do your turn signals and 4-way flashers work properly? If not the t/s switch could be causing both problems.

Answer 2

First thing is to check all ground wires and connections. If all other fuses in the box are getting full voltage, then trace through all wires associated with the brake circuit for shorts to ground. good luck

Answer 3

I am a computer guy so I think elsewhere. whatever is supposed to actuate the lamps when you press the brakes....check there.

Answer 4

sound like a ground fault in back of the box

Answer 5

maxy fuse blown bad fuse able link