I have a 1968 F250 camper special. And what do you know, the brake lights don't work. I have checked that I have power at the pedal switch, so that is good. Both left and right turn signals work.
Where do I look next?
Does any one have a schematic of the wiring for this year?

thx for the help.

 

Did you actually check the bulbs itself? It's not that uncommon for both brake lights to be burned out. Usually, one burns out and you don't notice until the other one burns out leaving you with none. I also had to run a 1/2" copper pipe brush in the brake light socket to clean out the crust in order to get a good contact with the bulb.

 

Maybe the switch itself is bad. Did you check the switch itself with a voltmeter to see if you have continutity when its in the open position? also see if its adjusted properly as so the button pops up when you depress the brake pedal.

Even though your turn signals are working, it could still be the turn signal switch. I'm having the same problem with a single brake light not working, however both turn signals work and it is turn signal switch related.

 

The brakes and turn signals use the same bulb, wires, etc from the turn signal switch to the rear of the truck.
So if you have power into and out of the brake switch and into the turn signal switch....I would have to say the turn signal switch has faiuled internally.

 

Check the turn signal switch. If you don't look closely, you'll wish you did!

 

The brakes and turn signal do use the same bulb, but they utilize different filaments. I'd test the wires at the socket first before I pull the steering wheel to check out the switch.

 

Sorry but the brakes and turn signals use the same filiments. The other filiment is dedicated to the tail light. The turn signal switch turns off the brake light on the selected side and then makes it flash.

 

One of the joys I've found with older trucks, especially when they've been used to tow is the wiring. It's almost a given, that almost every owner of the truck has at some point, "customized" the wiring to suit their own particular trailering needs.

Check the wiring at the back of the truck under the bed. When I got my truck, their was huge monkey fist of electrical tape covering what appeared to be several botched attempts to install a trailering harness.

 

when you push on the peddel(brake) there is a little almost spark plug looking thing.......It can burn out break and what not.....you may look at that........Just a thought......( the thing turns the Brake light on when you puch down by releasing a little peace of plastic wich conect to another...give it a try..maybe...)

 

Definitely check all wiring to the back and rip out all PO stuff and restore to normal. I'm sure the complete wiring diagram is available on this site. Also, check https://www.ford-trucks.com/articles...elecrepair.php or look in tech articles for 70's turn signal diagnoses that has the basic colors for the turn signal/brake light circuit.

Joe

 

Easiest way to localize the problem, is to disconnect the wiring harness under the hood where it exits the firewall on the driver's side. On my 1971, its a square plug with four wires. Stick a probe in there and see if it lights up when you step on the brakes. If it does, then you know the wiring problem is after the firewall.

If it is inside the truck, I would check the flashers first. I do not have the shop manual handy, though I seem to remember the stop lamp gets its 12v from the flashers.

 

If you have turn signals that are flashing in the tailights then you must have a good circuit to them. you have eliminated that. If you have power to the brake light switch you have eliminated that. If you have power out of the brake light switch and into the column connector then It can only be in the turn signal switch. Simple process of elimination.

 

from my first inspection, it sure looks like the turn signal switch.
Where is the best place to get a replacement?
I take it the only way to replace it is to take the steering whell off.
Do I need a puller to do it, or does it just pull off?

thanks for all the help

BW

 

I found a vintage parts dealer that can get the switch for a 68 F100, I am hoping it is the same for the 250, does anyone know if this true?

 

Should be the same. I just changed mine out on a 70 250. The only cautions I would give you is be careful with the horn contact brushes and make sure you use a fish line on the turn signal wiring harness when you pull it out of the steering column. You'll have a lotta fun if you don't.