Brake light fuse pops every time you tap the brakes

[porschpow]

On my brother's MGM (1986 LS), everytime he taps the brakes, the fuse pops. His brake lights are gone. Any idea what could be tripping this fuse?

We even tried to use a higher 20 amp fuse...same problem

[miamibob]

Sounds like a short. Don't think you want to use a higher capacity fuse as that could cover up a bigger issue.

[sly]

Either the brake pedal switch or the multifunction switch or a wiring issue.

[porschpow]

yeah the bigger fuse was an experiment.

Where can I find the brake light switch/multifunction switch?

I am assuming if its a wiring issue I would have to go down the whole wire loom from the front to back, no?

Since fuses are linked to other operations in the car, im sure the fuse powers more than the brakelights, right? But since the fuse blows when i touch the brake pedal, I can automatically assume we can narrow it down to the brake light circuit, right?

[miamibob]

Do you have the Owner's Manual to look up the fuse list? That will tell you what they power or you can look it up online.

[porschpow]

Unfortunately, we were unable to find the owner's manual for the fuse lcations. It would've made sense for Ford to put a sticker display on the panel lid, like every other car made, LOL!

[Lincolnmania]

the multifunction switch or the brake light switch yea slymer is right on.

the brake light switch is down on the brake pedal where it hoooks to the brake booster rod


the multifunction switch is under the column trim, easy to change also.

[porschpow]

Thanks for the pic, Scott. But where is the switch on the booster. I am looking at the pic, can't find anything. Only thing I see is two wires near the booster side.

As for the Multi function switch...do you mean the stering column trim???

I am assuning its cheaper and easier to just buy new?

[johnunit]

The switch is inside the cabin under the dash. It's made of black metal and sort of hooked around the top of the brake pedal arm. Follow the brake pedal arm up and look for a wire going to the pivot

[sly]

also, the multifuction switch is the blinker switch on the steering column. If you unplug the multifunction switch and hit the brake and the fuse still pops... it's probably the brake switch. If not, probably the multifunction switch or wiring from there to the trunk.

[85crownHPP]

Start simple - remove and inspect all the brake light bulbs/sockets first, see if it pops with all of them removed. The contacts on the bottoms of 115X type bulbs can melt and spooge out of place, corrosion in the sockets can make them fall apart and short out. Also replacement sockets like to fall apart for no reason.
Had your brother done anything to the car recently before this happened?

[gadget73]

Use a heavy jumper wire to bypass the fuse. Step on the pedal. Wait for smoke to come out and look there. Hope the car doesn't burn in the meantime



Common problem is finding a single contact bulb where a dual contact bulb goes. That will short the two pins and cause you all sorts of nonsense. Do the turn signals and parking lamps work correctly? If so, that should clear the actual tail lamps and their wiring from MF switch out to the lamp socket. That leaves the third brake light, the brake light switch, and the MF switch itself. If the turns and/or parking lamps do not work correctly, then you're looking for problems in the left or right rear lamps, depending which side doesn't act right.

[wa9zug]

Instead of popping fuses, install a small 12 volt lamp in the fuse socket. It will light up when you have a short. You can also use a 12 volt buzzer. Then dink around and pull connectors etc. until the short goes away.

[porschpow]

These are all good suggestions, I wil be sure to shae this info with him.

He's nis not the most auto savvy, so I will help him. He probably installed the wrong bulb.

Where exactly on the steering column is the multifunction switch?



In addition the turn signal stalk won't stay up or down when you use it to change lanes or want not. I don't know how to xplain it, but its the retainer like thing that keeps the turn signal in that position until you put it back in its neutral position. I think this is a common problem. Is it just cheaper and easier to get another one from the junkyard?

[sly]

the turn signal stalk is on the multifunction switch (same part). sounds like that's the issue and probably needs to be replaced.

Remove the column shroud and it's 2 bolts and a couple connectors and swap. pretty easy.