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Just bought a 1966 F250 Custom Cab Deluxe and don't have any brake lights. I traced the wires back from the lights, one green and one black. The green seem to be the blinkers and they work. The black one I can't find how it connects to the brake pedal for it to work. Any help would be appreciated.
Normally in '66 the brake light switch is mounted on the master cylinder. It is a hydraulic pressure switch instead of an electro-mechanical movement type switch. The switch has two wires hooked to it and if you jump them together it should turn the brake lights on. If it does-replace the stoplight switch or check some of the recent discussion on why you should convert to the later pedal mounted switch.
I had the same problem with my 65 and I Jerry rigged the connect to the hydraulic pressure switch which works fine after 39 years. I think a brake switch would be better though. I'll convert mine over some day.
Keith, Do the other functions work on the rear lights, like tail and turn signal?
There are three wires used to make everything work. One is used for the tail lights and license plate. The other two are left & right signal and brake. The brake shares the signal wire. Putt has described how to test that circuit.
On all the 61 to 66 trucks does the key have to be on for the brake lights to work?,my 66 is the first vehicle I have had that the key had to be on for the brake lights to work. I had a 50 chrysler that the key had to be on for the horn to work but usually the brake lights have constant power.
Thanks for the replies guys. Been raining for most of the day here so I couldn't really work on the truck. I will try out the lights tomorrow with the key on. Yes all the other lights work just fine.
Got a test light? If you don't you can get a cheapo at Autozone for $3. A MUST for anyone with any plans at all of maintaining an older vehicle. The only trick is making sure that your alligator clip lead is hooked to a good ground and not painted or corroded surfaces.
On the brake light wires you will be able to touch the test light probe to each one with the key on. Your light will come on when you find the "hot" one.
You can make your own test light with any 12 volt bulb, a socket, some lengths of wire, and some insulated alligator clips. You could buy one cheaper than buying the stuff to make one but if your like me you've got the stuff laying around.
The brakes quit on my 65 once and I traced the problem to the plastic wiring connector under the dash. It had enough corrosion on the terminals to stop the current from flowing. I had to bypass the connector.
This may not be the problem you are having, but it might help.
Dittos Greg! Ya aint gonna fix anything without a tester.
My preference is the icepick looking kind with the bulb in the handle and 2 ft. of ground wire with an insulated alligiator clip. I would also spend a couple bucks more for a good one. I had an elcheepo one that came with a kit that bit the dust real quick.
I also like a small tackle box to keep connectors, extra bulbs, fuses, extra wire, wire cutters, and other tools in. It is easy to grab the tacle box and have most needed things at hand.
When my brake lights quit, it turned out to be the connection at the switch on the master cylinder. I mashed it a little with pliers and put it back on. Voila! Now it works.
Well this might just be the answer to your problem, The colors will tell a lot about the truck unless somebody did some wire replacement. Your turn signal switch and the wires going down the steering housing intercept your brake light relay under your dash. There will be two wires coming from your engine compartment and will be intercepting a hookup. It is a power splitter connector. Sometimes debris gets in the hook up and causes the current to short or impede. Check this area. Your wires will then go back out through another wire setup to your front lights and to your rears. Black is usually hot or ground. They changed the color code through the years of 61-66. Your brake light sending unit on your master cylinder might be bad. Check that with a test light to see if you have current. From there it is just tracing wires. Good Luck
Probably to late to add my 2 cents; I also recommen ensuring that the ground connection where you screw the tail light housing to the body makes metal to metal contact as well as possible brake light sending unit being bad.
C.C.
yea we have a 66 f250 and wiring still isnt figured completly out. i was just curious as to what engines, trannys, and rear ends you guys have in your 66's. strange that ours has a 240. that seems like a tiny motor for an f250. thanks