Brake lights won't work and I'm getting frustrated

[STFTW]

Ok I just bought a 2001 Sport but I just found out the brake lights don't work. The 3rd brake light works so I know its not the brake switch. I checked all the fuses, changed the bulbs and they still didn't work. The wiring looks fine. Also I tested the trailer plug for power and it wasn't getting any. Related possibly?

I temporarily ran a wire from the 3rd brake light to the left tail light and both brake lights work, but the only problem is when I have the left turn signal on and hit the brakes, it stops blinking. The right one works fine though. Any idea what I can do to get my lights to work properly?

 

[budwich]

you need to check for voltage with a meter. If there isn't any, there you need to follow that circuit back to a splice or connector. If there is voltage, then its a ground problem. On brakes, there is a splice between the third brake and the other two PLUS on some ex's, there is a LOM module that could be a problem.

 

[Vinniety]

Ok I just bought a 2001 Sport but I just found out the brake lights don't work. The 3rd brake light works so I know its not the brake switch. I checked all the fuses, changed the bulbs and they still didn't work. The wiring looks fine. Also I tested the trailer plug for power and it wasn't getting any. Related possibly?

I temporarily ran a wire from the 3rd brake light to the left tail light and both brake lights work, but the only problem is when I have the left turn signal on and hit the brakes, it stops blinking. The right one works fine though. Any idea what I can do to get my lights to work properly?

I noticed alot of wiring in the comparment where the jack is located. I will look in there for any shorts and trace back. Are you sure you checked the right fuses? Also what about when you turn on the lights did the lights come on? I would see if there is any power going to the bulb sockets. You never know the sockets might be bad. I had a car that one light wouldnt work and there was power to that bulb when i hit the brakes. I ended up using wd40 in the socket and using a small pick to clean the connector becasue i did see some minor corrusion and bang it worked. After that i started to use grease in the sockets so it doesnt get any corrosion in the future. Grease will not interfear with the electric power.

 

[STFTW]

All the other lights work just fine, it's just the lower brake lights that didn't work. They all use the same ground don't they? I tested for power at the bulb socket and it got no power when the brake pedal was pushed.
Where might this LOM module be located?

It's not a bad socket or anything like that, its just not getting power.

 

[DR98]

I don't know if the 2001 is the same, but I checked my 98 Ford Explorer wiring manual -

All the brake lights share the same 12 volt feed line. The 3rd brake light has it's own ground wire. The left and right tail \ brake lights share the same ground wire.




Dean

 

[budwich]

The lights out module (option) is in the center console if you have that option (not sure about sports models). I only have 96 drawing but the splice that feeds both your back stops and the third light is near the data link connector which I think is in the engine compartment on the drivers side but not sure and I haven't found any more info on that.

NOTE: after looking closer at the drawing, there is also a splice for the anti-theft module (bet you got one of those). Depending on your config, its near the rear washer pump in the four door (96 reference) and near the rear left side speaker in the 2 door models. Hope that helps.

 

[STFTW]

Well I know its not a ground because the brake lights work when I power from another source. I'll check out those modules and see if I can find anything.

 

[gijoecam]

Guys, an '01 sport is a little different than the others... They did away with the separate bulb for the turn signals like on the 98s. The wiring is a bit different...

The brake switch is fed from one circuit, but the stop lights are fed through two different circuits and share a common ground. The brake pedal position switch feeds power directly to the CHMSL, and splits that feed to go to the shift lock actuator, speed control servo, PCM, 4WABS module, and the brake switch relay in the battery junction box. Now, from there, that relay feeds the multifunction switch which, in turn, sends the signal to the front and rear turn signals. Soooo....

That begs the question: When you turn the signal on, do the front turn signals work? If so, we can rule out the relay. If not, I would suspect the relay first. Start there and let us know.

-Joe

 

[STFTW]

Guys, an '01 sport is a little different than the others... They did away with the separate bulb for the turn signals like on the 98s. The wiring is a bit different...

The brake switch is fed from one circuit, but the stop lights are fed through two different circuits and share a common ground. The brake pedal position switch feeds power directly to the CHMSL, and splits that feed to go to the shift lock actuator, speed control servo, PCM, 4WABS module, and the brake switch relay in the battery junction box. Now, from there, that relay feeds the multifunction switch which, in turn, sends the signal to the front and rear turn signals. Soooo....

That begs the question: When you turn the signal on, do the front turn signals work? If so, we can rule out the relay. If not, I would suspect the relay first. Start there and let us know.

-Joe

Yes the front turn signals work.

 

[gijoecam]

OK, how comfortable are you working on the electrical system? This one's a runner we've got to chase...

We know you've got juice through the fuse, flasher relay, and into the multifunction switch as evedence by the fact that the fronts work. The front and rear outputs from the MFS are fed from a common source.

Coming out of the MFS, you should have a DB/WH wire and a BN/YE wire. Check for power on both of those when you either apply the brakes, turn on the hazards, or turn on a turn signal. If you've got juice there, we'll need to poke around behind the fuse box a bit for the next step.

-Joe

Also, gotta ask: Did you check for power at the OG/LB wire at the right taillight and the LG/OG wire on the left light? Check it with a test light and a multimeter when hitting the brakes or turn signal....

 

[STFTW]

OK, how comfortable are you working on the electrical system? This one's a runner we've got to chase...

We know you've got juice through the fuse, flasher relay, and into the multifunction switch as evedence by the fact that the fronts work. The front and rear outputs from the MFS are fed from a common source.

Coming out of the MFS, you should have a DB/WH wire and a BN/YE wire. Check for power on both of those when you either apply the brakes, turn on the hazards, or turn on a turn signal. If you've got juice there, we'll need to poke around behind the fuse box a bit for the next step.

-Joe

Also, gotta ask: Did you check for power at the OG/LB wire at the right taillight and the LG/OG wire on the left light? Check it with a test light and a multimeter when hitting the brakes or turn signal....

I'm not bad with wiring but I'm gonna need some clarification. What is the MFS and where is that at?
All the lights worked, turn signals, drl, hazards, headlights, with the exception of the lower brake lights. So far I've tested the light bulb sockets on both sides for power when the brakes were applied and got nothing. I tested one of the wires on the brake switch and it was getting power so I'm assuming the switch is fine. Thats about as far as I have gotten with it. Its cold outside, lol

 

[gijoecam]

Sorry... I'm speaking in acronyms again LOL! MultiFunction Switch... turn signal/windshield wiper/high beam control switch.

If the front turn signals and the center high-mounted stop light (CHMSL) is working, it's not the brake pedal position switch. That's why we need to check for power into and out of the multifunction switch.

-Joe

 

[jereratli9]

Sorry... I'm speaking in acronyms again LOL! MultiFunction Switch... turn signal/windshield wiper/high beam control switch.

If the front turn signals and the center high-mounted stop light (CHMSL) is working, it's not the brake pedal position switch. That's why we need to check for power into and out of the multifunction switch.

-Joe

I has the same exact problem with my 01' sport. After many trial and error fixes on my part I took it to the dealership. Turned out it was a bad MFS. They replaced it and everything went back to working properly If I were to take a guess at what it would be I'd say the MFS. Seeing as how I had the same EXACT problem on the same EXACT car.

 

[gijoecam]

I has the same exact problem with my 01' sport. After many trial and error fixes on my part I took it to the dealership. Turned out it was a bad MFS. They replaced it and everything went back to working properly If I were to take a guess at what it would be I'd say the MFS. Seeing as how I had the same EXACT problem on the same EXACT car.

Indeed, that's the most likely culprit... the latest check should pin it down. Power in, no power out points to a bad MFS.

 

[kdkinc]

Mfs

Thank You both "STFTW & gijoecam" for the post you both carried on. Had the same issue.
The Multi Function Switch is the culprit.
In my case.
I stepped on the brake pedal and used the steering wheel tilt function.
In the lower position I loose the brake lights.
Now I know what ill be doing later. LOL

Thanks again

 

[Spencer01]

I have the same problem with mine and ive replaced everything i just don't know how to check voltage

 

[MrWittyOne]

My 98 explorer is having same problem--all lights work except bottom brake lights. How is the MFS controlling the brakes. My hanes book doesn't show it operating the turn signals, headlights, & wipers.