I have an 1987 F250 with a 7.3L diesel that has a problem. I have no brake lights. turn signals, hazzards, headlights and tail lights work fine. I replaced the hazzard flasher, brake switch (that is attached to the brake pedal), and the turn signal switch. bulbs are all good. Also the turn signal fuse blows often. I am at a loss. Please help. If you have had any of these problems and (hopefully) solved them please let me know.

Robert
87 Ford F250 Diesel

 

I had a trailer brake controller go bad that did this. Might be worth a look.

 

Crap......I was hoping to find a quick fix. now I need to price out a trailer controller. Thanks I will give it a try.

 

Unhook it and see what happens first. I could be wrong!

 

I have a brake controller on my 1957 ford f100 that I don't need maybe I will try to switch them. If this wasn't my daily driver I would park it and wait until I had more money and time, but such is life.

 

IF, and I sat IF, it is the controller, the only link to your problem is the activation wire. This wire is connected to the brake light switch at some point. When you replaced that switch, did you notice any add-on wires connected to it? And how was the installation? Twisted together with electrical tape or those blue square things(scotchlocks) or was it done correctly? Simply stepping on the pedal can move a wire and make it contact something it isn't supposed to. When mine went it was shorted inside. I simply unhooked the a fore mentioned wire and the problem stopped. Then I took the controller apart and found the real problem.

Do you tow a lot with this truck? Do you have a 7-way trailer plug? Some of them have a separate brake light circuit that would also cause this but have no effect on turn signals, etc.

 

There are the square blue things. I will disconnect it tomorrow. I hope this solves the problem. I don't tow very often. I have the 4 plug. I really appreciate all the help.

 

With the 4 plug, you have no brake power going to the back anyway so disconnect it, tape up the bare wires, and see what happens. If its fixed HOORAY! Take the controller out and trash it. No need to put another back in. Unless you want trailer brakes and if you do, we need to start a new thread!

 

Or you could diagnose it correctly by using a DVOM or a Power Probe and find where you're losing voltage.....

Tip: fuses typically blow due to a short to ground. You may have a wire where the insulation is worn through somewhere.

 

I went back and read the OP. You said you had no brake lights but the turn signals work fine. Then you said the turn signal fuses blow often. So the turn signals DON'T work fine!

It won't hurt to unhook the controller, but closer diagnostics do need to be done.

 

Removed brake controller and had brake lights. but now they are out again. I hate chasing wires. looks like I will be spending quality time with my fluke....Thanks for the help. I will keep you posted on the progress.

 

I have an '87 460 that had a problem blowing fuses with the brake lights and turn signals. (both the #1 & #5 fuses)
After a lot of poking around I found that the insulation had pulled back from a plug in the harness.
It was in the engine bay beneath the brake master cylinder.









Not saying that this is your problem, but it is worth a look.

 

Thanks Jim I looked at that connector and found 3 wires like the ones you found. I insulated them with electrical tape. Didn't get achance to check for the brake lights yet. Will do tomorrow. Again thanks to all for the help

 

The saga continues........I hate electrical problems. Got up to go to work at 4am and the truck wouldn't start. everything turns on so I though it might be my ignition actuator(I had it break on me before) but it was fine. Truck would crank when I jumped the relay but not start. I must have damaged a wire when insulating the wires. Looks like I will have to do a lot more than I was hoping to. If anyone has any insights I would love to hear them. Thanks guys and girls.

 

OK I r & r'd my multifunction switch (again) and completely removed the brake controller. All lights work again but truck will not start from key. I turn the key and nothing happens except my temp gauge goes all the way up. I can now jump the relay to start the truck. I will begin a new thread for that now......Ugh. I guess I can't complain too much truck hasn't given me hardly any trouble until now except it won't switch tanks. Thanks to everyone for the help.