brake light question

[texas trux]

we are having brake light problems my question is can you check to see if you have a short at that solenoid on the master cylinder we are working on a 1965 ford 1/2 ton tail lights work just fine

[65 66 Ford]

Yes, you can check the switch. It is actually a pressure operated switch that does go bad. The switch should read open until you apply pressure onto the brake pedal. When pressure is applied to the brake pedal the switch should read closed.

If the switch is bad you should think about installing a newer type plunger switch inside of the cab that works off of the brake pedal arm. There are some topics here that explains how to do this.

[DanSanDiego2000]

TT,
I too have a '65 F100, and had several light/brake issues.

That 'solenoid' you mentioned is a pressure activated switch. When the fluid pressure is great enough, the switch closes, and your lights work. If there is not enough fluid, or air in the line, the lights won't work. If the fluid is full, and the lines are bled, check the switch with a test light. The switch should work when the pedal is pushed. If the switch is bad, replace it.

However, if your turn signal switch is worn or broken, and does not 'click' into the center position properly, the brake lights won't work. The detent for left turn, for right turn, and for the center spot allow the circuit to be completed and the brake lights to come on. If the lever gets hung up in the in-between areas between the detents.... no brake lights.

And last but not least (and not last either), the fuse panel can become corroded, and not allow continuity through the fuses. An auto electric shop found my fuse panel corroded, removed all the fuses, sandblasted the terminals, reinstalled the fuses, and ALL KINDS OF STUFF on my truck started working again. The dome light, the dash lights, the radio, the blower motor all had been silent and dark for years. Once the fuse panel was cleaned, many issues were resolved.

I changed my brake pressure switch first (without testing it) because it was inexpensive and simple. It did not change anything. Check your fluid, bleed if necessary, test your switch, then move to the turn signal switch and then to the fuses. I imagine that somewhere in this search, you will find the culprit.

If your turn signal switch is wobbly/loose, try moving it to the left, right and center positions while you have the pedal depressed. With someone watching the brake lights, you should be able to determine if the brake lights work while you wiggle the turn signal.

Let us know how it works out!!

Dan

[Roger Carter]

I chased a couple of brake light problems on my '66, and am pretty sure the '65 would be the same.
I was showing an electrical short circuit, traced it to the pressure brake light switch. Found the insulator, at the base of the terminals on the switch, to be cracked and filled with grunt, allowing a slight current to flow to ground. Replaced the switch and the problem was solved.
Another item to remember is the brake lights do not work with the ignition key off. Once I learned how the system "worked" the problem went away. This is different than most vehicles, where the brake lights are "hot" all the time.

Roger Carter

[Michelle]

My 64 Falcon had a brake light problem and I traced it to the turn signal switch also. The Falcon and the F100's of the era share the same steering column. If you need I can post a wiring diagram of the 65 66 model for you. As a matter of fact I have master wiring diagrams for all Ford trucks from 1963 on up to 1972, if there is any other wiring diagram you need let me know.