Cobra Brake Booster and Brake lights

Shakerhood · Jun 17, 2005

I finally got my 93 Cobra Booster installed in my 92 GT tonight and as I was working to install those 4 PITA Nuts I noticed my Brake lights were on, I fiddled with the pedal and got them to go out, but if I just barely touched the pedal with my finger the lights would come on and stay on so I pulled the fuse. After I finally got all 4 nuts tight I could not get the lights out at all, so I just left the fuse out. I dont have the M/C installed yet nor did I hook my clutch cable back up yet, any ideas to why my Brake lights wont go off now? I know I installed everything back on the brake pedal correct because I drew a diagram before I disassembled it.

Shakerhood · Jun 18, 2005

TTT Can anyone offer some help?

Shakerhood · Jun 18, 2005

I double checked everything, no wires were in a bind and the switch is installed correctly. I removed the switch and am going to try to replace it with a new one, but I cant see how this one could go bad from just removing it from the brake pedal and reinstalling it back on.

89MustangGX · Jun 18, 2005

The switch is adjusted by bending the metal tabs near the pedal. It also can hang up if you push it one way too far. I would put it back on and see if it does itstill. If so, try pushing up on it (I think) a little and see if that helps. It doesn't take much to adjust it or knock it out of adjustment.

Shakerhood · Jun 18, 2005

89MustangGX said:
The switch is adjusted by bending the metal tabs near the pedal. It also can hang up if you push it one way too far. I would put it back on and see if it does itstill. If so, try pushing up on it (I think) a little and see if that helps. It doesn't take much to adjust it or knock it out of adjustment.

I have the switch in my hand and I am trying to figure out how to make an adjustment on it? There is a slight curve in the metal piece that rides on the booster hook up. One idea suggested to me was to crank the booster rod out side the car in the engine compartment back inward, but I measured stuff before hand and everything seemed to be correct, I feel like I wil lose out on braking performance by doing that.

Shakerhood · Jun 18, 2005

Using a formula from maximum motorsports to check pushrod length from the booster, mine is .007 too long, now I may be off .001 or so, but I just cant see such a small number having an effect back in the brake pedal and switch. Unless the pushrod itself adjusts back and then you can turn the nut back out again, any more ideas from anyone?

89MustangGX · Jun 18, 2005

Shakerhood said:
I have the switch in my hand and I am trying to figure out how to make an adjustment on it? There is a slight curve in the metal piece that rides on the booster hook up. One idea suggested to me was to crank the booster rod out side the car in the engine compartment back inward, but I measured stuff before hand and everything seemed to be correct, I feel like I wil lose out on braking performance by doing that.

This is about the only pic I could find online of the brake light switch:

If you look at the silver metal part in the pic, just past where it mounts on the brake pedal, that is the part that would bend to adjust the switch. It doesn't take much to adjust it, so try and bend it a little at a time -- you will see how it works when you start.

Shakerhood · Jun 19, 2005

I think I might have fixed it because when I hood the vacuum hose up to it and started the car, the lights worked like they are suppose to. Now after the vacuum bleeds off they may come back on, so I pulled the fuse to be safe for now.

89MustangGX · Jun 19, 2005

Shakerhood said:
I think I might have fixed it because when I hood the vacuum hose up to it and started the car, the lights worked like they are suppose to. Now after the vacuum bleeds off they may come back on, so I pulled the fuse to be safe for now.

Hmm...I think I would suspect that the switch was just a little off and getting hung up on something -- but you fixed it when you put it back in. Can't see vacuum affecting it, especially since they should work without any vacuum (car off) normally.

Nice job regardless -- I bet you have no more problems.

Shakerhood · Jun 19, 2005

89MustangGX said:
Hmm...I think I would suspect that the switch was just a little off and getting hung up on something -- but you fixed it when you put it back in. Can't see vacuum affecting it, especially since they should work without any vacuum (car off) normally.

Nice job regardless -- I bet you have no more problems.

My theory behind it was that with vacuum it would push back on the pedal. I pulled the fuse last night just in case the vacuum bled off and would cause them to come back on. Well, I plugged the fuse in and they came back on, I lifted up on the pedal and they stayed off even with me slamming the door. I still dont have the M/C hooked up and think that would apply rearward pressure to the pedal too and I had hoses off the vacuum tree over night. I guess I am down to trying to replace that switch.

BlackFox5.0 · Jun 19, 2005

The same thing happened to me, i took out the switch many times before realizing it was geeting caught on the steering column (I think). I put a ziptie on the wires and that pulled it up and away from getting caught on anything again, and problem solved.

Shakerhood · Jun 20, 2005

BlackFox5.0 said:
The same thing happened to me, i took out the switch many times before realizing it was geeting caught on the steering column (I think). I put a ziptie on the wires and that pulled it up and away from getting caught on anything again, and problem solved.

I have been laying on the floor and pressing the pedal with my hands and can see it is not getting hung up on anything. I hooked up the M/C tonight and when I depressed the pedal the lights came on, but they also went off while the pedal was still depressed and it did that a couple times. The only time it operated right was after the car was off and the pedal got hard it moved barely forward and they would come on, and pull it back and they would go off. I am pretty sure the switch is bad, I dont know how as all I did was disconnect it and reconnect it, but thats all I can think of.

Cobra Brake Booster and Brake lights

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