Brake lights started flaking out

[eunosracr]

So the brake lights started flaking out today. I have LED bulbs but they only work sometimes when i press down on the brake pedal. Should I just bite the bullet and replace the switch that goes to the master cylinder? I doubt its the bulbs since both sides are acting exactly the same from working, to dim, to flashing, to not working at all. Any suggestions?

[mln385]

Check the connection on the switch, might be loose. It is a common problem on these cars.

[ct clint]

Try a meter or test light on out put side of switch. See if it's switch or jump the switch see if they work

[eunosracr]

Thanks guys. Will try this and report back.

[Tommy]

Bad and intermittent grounds are very common on fiberglass bodied cars. If both brake lights are grounded through a common wire, that could be it. A quick test is to run a temporary jumper wire from the brake light fixture ground to a known good ground. If that makes the problem go away, you have identified the source of the problem.

[Cashburn]

Take the two wires off the switch and connect them. If it works perfectly than it's the switch.

[eunosracr]

Originally Posted by Cashburn

Take the two wires off the switch and connect them. If it works perfectly than it's the switch.

Jay- Do you mean with a jumper wire? Also the brake lights do seem to work if i really press down on the pedal. Does this sound like the symptoms related to a bad switch?

[twobjshelbys]

Check grounding. The tail light is grounded by a wire to the chassis somewhere. Try attaching an alligator clip lead set to the light and a chassis ground. At a minimum clean paint off the chassis area where the ground return is connected to the frame.

[Tommy]

Originally Posted by eunosracr

Jay- Do you mean with a jumper wire? Also the brake lights do seem to work if i really press down on the pedal. Does this sound like the symptoms related to a bad switch?

The switch closes the circuit (i.e., connects the two wires attached to it) when the pressure is high enough. Connecting the two wires together either with a jumper or by disconnecting them from the switch and pressing them together will bypass the switch and should turn the brake lights on. If that solves the problem, then your switch is the likely problem.

[eunosracr]

Originally Posted by Tommy

The switch closes the circuit (i.e., connects the two wires attached to it) when the pressure is high enough. Connecting the two wires together either with a jumper or by disconnecting them from the switch and pressing them together will bypass the switch and should turn the brake lights on. If that solves the problem, then your switch is the likely problem.

Thank you Tom !

[Late Apex]

With only 645 miles on my new BDR Cobra, the left brake light went out last week. On inspection of the bulb it was black and done. Right side ok. Ordered GE 12v 5w brake bulbs from Amazon, 2 to a pack, and they work great and are brighter than whatever brand the factory uses too. Hope you correct the problem that easy.

[eunosracr]

Problem solved by replacing the switch. Cheap and easy fix. I bought an extra one just in case.

[picross]

There is also a heat shield you can buy to help keep the switch on the master cylinder from failing (too close to the headers apparently). I have an early backdraft (#157) and it did not come with the shield - my switch failed also and i put the shield on. I ended up also installing a mechanical backup as well just to be safe.

[tamanaco]

the switches used on BDR cars have been failing since the 1960's when it was very common brake switch in production cars...Ford's i think. They just failed! the best solution is a mechanically actuated switch by the movement of the brake pedal...you'll never look at it again!