Brake Lights Stopped Working on a 1992 SHO - Please Help!

[SHO---]

Dear SHO Forum,

The brake lights on my '92 SHO quit working after being placed in storage for a while.

Here's the deal...

All of the lights function great except the brake lights. The taillights, reverse lights, turn signals, etc. all work fine.

What I've checked so far:

Battery- new and good, will start the car....

First, I checked the little 2-wire micro-switch down at the pedal arm with my tester...got continuity on/off whilst working the switch- good.

Next, I tested for 12Volts going into the micro switch- yes- good, getting power in and out.

Next tested the brake light bulbs, weren't sure which bulbs were the brake lights but through process of elimination figured the middle bulb must act as a brake light- figured the outer bulb though a turn signal, may also double as a brake light too (help me out here guys). Said what the heck- check all of the bulbs for continuity- they were all good (yes I was careful to check both filaments in bulbs that double as other things).

Next, I decided to see If I was getting 12Volts to the brake light bulb sockets. Problem- was alone, and did not know if the key has to be in the ignition, etc. to get the brake lights to activate- (help) assumed that the key does not have to be in the ignition and proceeded...no mirrors laying around so I laid/leaned a piece of heavy cast iron metal against the brake pedal (yes I know I could have jumped the micro-switch but that would have been too easy). Anyway, went to the back to check for 12Volts and low and behold the third brake light started to slightly glow, and also the reverse lights came on (was parked in reverse gear). I thought to myself, what the heck? Do the reverse lights come on in an SHO when it does not have keys in the ignition? That can't be right? How is it doing this? The 2 main R+L brake lights where not on. The 3rd brake light faded away and the reverse lights cut off. I said to myself, "I bet the ignition switch contact points have some condensation/carbon on them from storage- I'll work the ignition switch back and forth a few times and I bet they'll work." So I opened the door, and to my surprise I smelled the worst of all do-it-yourselfer smells- yes, burning wires!!! I could not find smoke or burned wiring anywhere.

I also thought about the relay- thought perhaps it was stuck and fried out. Where is the brake light relay located?
I would like to check it but can't find it.

Something of interest- When I first got in the car last week from storage and drove it, I had tar all over my left foot- I thought I had tracked it in and gotten it all over my floor mat- whilst trouble shooting this problem, I have discovered that the "tar" is actually from a "melted rubber stop" for the emergency brake lever pedal. It had turned into a "tarry ooze." Has anyone else witnessed this strange phenomenon? It appears that the emergency brake lever pedal also has a 1-wire micro-switch/sensor? The emergency brake was "OFF" but could the switch- all gooed up with melted tar, have "freaked out something." Could that have been the smell- that melted tar all around that 1-wire micro-switch/sensor? What does that switch do- what is it's function? That may help me out also if anyone knows. (checked- it is not getting any voltage- should it be?)

Perhaps the melted tar will light up somebody's light bulb out there.

Sorry for the long-windedness...I just wanted to be really clear so that I get a good accurate reply.

Thanks,

'92 SHO 5spd

 

[SHO---]

Woops! I forgot to mention that all of the fuses are good- under the dash and also under the hood.

'92 SHO 5spd

 

[kevinspann]

A majority of SHO's seem to be afflicted with the gooey e-brake pad. The rubber de-vulcanizes and that's what you are left with. The switch on there just activates the "BRAKE" light on the dash, to tell you the emergency brake is on.


I have found that a lot of Goo-Gone will get it out of the carpet, but it takes a while. I was told that lacquer thinner will work as well, but have not tried it.


Sorry I can't help with your lighting issue.

 

[Racer X]

Brake lights work with the key on or off, that shouldn't make a difference.

I've had to replace the 1/4 terminals in the connector with new ones, as they eventually spread, overheated, and separated from the wire. Crimping on new 1/4 female spade terminals is something to think about.

 

[Vsho93]

I bet the brake switch is the culprit, had mine stored for over a year and no brke light, switched and good to go

now on the same problem before the switch I also had it happen before, had a short at a terminal connection but it kept knocking out a main fuse under the hood at the far back driver side, cannot remember the fuse tho

 

[SHO---]

Thanks... but once again...

"Anyway, went to the back to check for 12Volts and low and behold the third brake light started to slightly glow, and also the reverse lights came on (was parked in reverse gear). I thought to myself, what the heck? Do the reverse lights come on in an SHO when it does not have keys in the ignition? That can't be right? How is it doing this? The 2 main R+L brake lights where not on. The 3rd brake light faded away and the reverse lights cut off."

How does that cause the reverse lights to light up and then shut off while the key is out of the ignition switch (shut off)?

Where is the Brake Light relay located at?

Any SHO gurus out there?

Thanks,

'92 SHO 5spd

 

[Racer X]

I still say to check or replace the 1/4 spade terminals at the BOO switch. If the terminals are bad, you'll see evidence of overheating on the connector or the switch (melted or distorted plastic, etc...)

On the reverse lamps illuminating along with the brake lights... are you positive that it was the bulbs, and not light leaking from one housing to another because of breakage or something else?

Also, IIRC, all of the lighting in the Taurus goes through the MFS. If you smelled burning wires, you would do well to check there for evidence of the connector overheating.

Good luck with the fix.

 

[SHO---]

The Micro-Switch terminals look fine- no signs of overheating, etc...does not work even when cut and spliced together.

The reverse lights were definitely on...no question about it! As far a lens breakage etc. the car is in extremely excellent condition.

What does "MFS" stand for?

Where is the brake light relay located?

I can't hear the faintest "click" when I jump the break pedal switch.

 

[Racer X]

That's because there isn't a relay.

MFS - Multi Function Switch. It's the stalk that contains your turn signals, 4-way flashers, high beam switch, flash to pass switch, and wiper controls.

 

[SHOCH]

Does the storys of headlight switch meltdowns have anything to do with this.
Also maybe dumb but you said storage, mice chewing wires.
Just a Friday night of Guinness and Harp induced babble.

 

[Racer X]

Does the storys of headlight switch meltdowns have anything to do with this.
Also maybe dumb but you said storage, mice chewing wires.
Just a Friday night of Guinness and Harp induced babble.

Tommy, I'm pretty sure that the only current going through the headlight switch is the headlights, parking lights, and fog lights.

Although, that current also passes through the MFS. Ask me how I know...

 

[SHO---]

Already checked for the "mice issue" but no signs- nests, droppings, chewing, etc. Besides, it looks like a fuse would be blowing if there were a short of that nature.

Any history of bad ignition switches on the 1992 models?

Where is the "MFS" or Multi-Function switch located?

Anybody out there with a factory service manual/wiring diagram they may could post as .jpg/.pdf?

Thanks,

'92 SHO 5spd

 

[Racer X]

Where is the "MFS" or Multi-Function switch located?

MFS - Multi Function Switch. It's the stalk that contains your turn signals, 4-way flashers, high beam switch, flash to pass switch, and wiper controls.

To access the harness or remove the MFS, you'll need to remove the upper and lower steering column shrouds. To do this, you'll need a phillips #2 screwdriver, a T-25 torx driver, a T-15 torx driver, and a 3mm or smaller hex key.

- Turn the ignition to "ON"
- Insert the hex key into the small access hole beneath the ignition cylinder and push upwards. What you're looking for here is the retention pin, you want to push it back into it's bore. It's small, so be patient.
- Once you've reset the pin, pull the lock cylinder, key and all, straight out, and put it aside.
- Remove the lower kick panel. It's held in with 4 T25 screws.
- Remove the screws securing the steering column shrouds, and remove them from the steering column. There are 3 long, and 1 short screw, IIRC.
- Identify the MFS (it's the only thing with a turn signal stalk coming out of it.), and inpected the connector and wiring for the aforementioned. Also inspect the switch for the same (it's held in with 2 T15 screws).

This is all off the cuff, and I don't have an EVTM at the moment, due to a computer crash.