This is for a '99 Expedition. The brake lights are not functioning. Here's what I've done:

1. All known related fuses have been checked and appear to be intact.
2. Third brake light over the rear gate does not function, either.
3. The emergency flashers function properly.
4. Brake light bulb filaments appear to be intact.
5. Brake (BOO) switch was replaced, but problem was not corrected.
6. All other functions on multi-function switch (blinkers, wipers, high beams, windshield wipers) work properly.
7. Tilt steering wheel was raised and lowered, and multi-function switch functions were conducted WHILE brake pedal was depressed, but brake lights did NOT come on.
8. Brake pedal was depressed while emergency flashers were activated, but brake lights did NOT come on.

I'm guessing it could be a wire that has shorted out. It's also possible that I haven't checked the correct fuse or relay. For the latter, does anyone know the actual descriptor of the fuse that controls power flowing to the brake lights?

Other suggestions before I throw in the towel and take it to a garage? I hate admitting defeat!

Thanks!

I have a '99 Expedition. The brake lights are not functioning. Here's what I've done:

1. All known related fuses have been checked and appear to be intact.
2. Brake light bulb filaments appear to be intact.
3. Brake (BOO) switch was replaced, but problem was not corrected.
4. All other functions on multi-function switch (blinkers, wipers, high beams, windshield wipers) work properly.
5. Tilt steering wheel was raised and lowered, and multi-function switch functions were conducted WHILE brake pedal was depressed, but brake lights did NOT come on.

I'm guessing it could be a wire that has shorted out. It's also possible that I haven't checked the correct fuse or relay. For the latter, does anyone know the actual descriptor of the fuse that controls power flowing to the brake lights?

Other suggestions before I throw in the towel and take it to a garage?

Thanks!

 

I have a problem with my emergency flasher switch on the column. When it is activated the flashers don't flash and the brake lights and blinkers quit working. Since brake and blinkers go through this switch it would be worth checking.

 

2Trux,

Thanks for your reply. I failed to mention that the emergency flashers work fine. The emergency flashers work fine. Just for kicks, I went ahead and turned on the flashers AND depressed the brake pedal, but the brake lights didn't come on.

 

But did the rear hazard lights flash on and off? (IIRC, the rear hazard and the rear brake light share the same filiment and the hazards have priority over the brake light.)

Unplug the BPP (Brkae Pedal Position) switch and check the harness side of the connector to see if there is 12v on the light green w/red stripe wire. (This wire should have 12v available at all times.)

If you DON'T have 12v, you have an open in the power circuit from fuse #13 in the Central Junction Box..

If you do have 12v, make up a small jumper wire and jumper the harness between the light green w/ red strip wire's pin and the next pin over, the one with the solid light green wire...............

If the brake lamps now light, you still have a problem with the BPP switch.

If they no light, you have an open on the light green wire going from the BPP connector up to or in the multifunction switch. (Since the left and right brake lamp feeds are on two separate circuits coming out of the multifunction switch, I'm guessing that they wouldn't both go open at once - - unless you know of something that might have caused both to fail at the same time.

 

It's fuse #15 under the dash that you need to make sure is good.
The 3rd brake light comes right off the BOO switch and doesn't run through the turn signal switch. This means you can rule out the TS switch as the problem.

 

Alloro - did I miss something again? I thought (there I go, thinking again) when the OP said that the brake lights didn't work I thought that the 3rd brake light wasn't working either.

I just dug out a wiring diagram - Your right, the 3rd tail light does run off the BPP switch, but so do the main brake lights. Power for the 3rd brake light goes from the BPP straight to the 3rd brake lamp while the power for the main brake lights comes off the BPP switch and detours up to the TS (Multifunction) switch. They do this so that the turn signal can have priority over the brake lights. That is, if the turn signal is off and the brakes are applied, power goes to each brake light, but if the left turn signal is on, the brake light current to the left brake light is switched off and the TURN signal pulses the left brake light. That way when the left turn signal is on and the brakes are applied, the left brake lamp doesn't stay on steady. Ditto if its the right side.

And it looks like there are TWO fuses that supply power to the BPP.

Fuse #15 is a 5A fuse that supplies power through the BPP. This current goes to modules like the 4WABS so it knows when to consider applying the ABS, and to the shift interlock so the gear shift can be moved out of park, etc.

Fuse #13 is a 20A fuse that supplies power for the turn/brake/hazard lamps.

So we really need to know if his 3rd brake light comes on when the brakes are applied. If it does, the BPP switch is good and the problem is in multifunction switch or the wires going from the MF switch back to the brake lamps. If it doesn't, the OP needs to break out the DMM and test for power at the BPP connector as described in post #4 above.

Now I have a head ache!

 

Read item #2 in the first post. That is why I said the TS switch can be ruled out. Since the 3rd brake light is not working, then the TS switch can be ruled out as the source of the problem.

 

Whoa, You are GOOD! (No, wait, I'm bad! )
I gotta slow down and read more carefully!

Since both the 3rd brake light and the regular brake lights don't work, the problem is before the MF switch. (That is, coming out of the BPP switch the 3rd brake light power goes straight to the 3rd brake light lamps, while power to the regular brake lights comes out of the BPP switch and is routed through the MF switch (so the turn signals have priority over the brake lights) and then back to the regular brake lamps.)

So, daddy dawg, you still need to break out the DMM and follow the steps in post #4 above to see where the break (pardon the pun) is.

Inquiring minds want to know

 

Hello, ello, ello, llo, llo, o, o, o, o...is there an echo in here?

 

First, thanks goes out to those who responded with suggestions to my initial posting regarding the brake light failure.

After trying some of them, I learned someone from my church runs an automotive electric shop, and I later took it there. I told one of the technicians all the trouble shooting steps I had taken (some of which were suggested by FTE members), and he replied all of those steps were exactly what they would have done, too.

It turns out a wire leading to the Brake (BOO) switch had burned out. This wire provides power to the brake lights, and goes through the BOO switch and up to the switches on the steering column before going out to the brake lights themselves. (Someone suggested I use a voltmeter to test the power to the BOO switch, and this would have narrowed the search. But since I'm challenged by replacing the batteries in a flashlight, this step was beyond my skill. When one starts saying exotic words like "volts, amperes, ohms" and the like, you might as well be speaking Yiddish to me.)

I occasionally pull a U-Haul or boat trailer, and the added power demands placed a strain on this wire, leading it to fry. I had pulled a boat several days ago, and it may have led to the light failure. This is troubling to me, since I was under the impression that this vehicle was designed from the ground up to pull trailers. It even had the "Towing Package" as one of its options. The gentleman at the repair shop said this would have never happened 20 or 30 years ago, because things like this wiring were much more robust then. He also assured me it will happen again if I pull enough trailers. Great.

At least there's some consolation that it took 12 years for the wire to burn through. If it takes that long to occur again, well, the vehicle would be an antique and would receive my compassion due to its senior citizen status.

At any rate, the brake lights are working once again, and I'm looking forward to getting back to the lake and burning out that wire again.

Thanks again, everyone.