When I got the truck, the wiring to the brake/tail lights had been cut off at the firewall for some reason. I ran new 16 gauge wiring from the firewall to tail lights and installed new bulbs. The wiring diagram in the shop manual I have shows 3 wires going to the tail lights, brown for brake/tail lights, yellow for driver's side turn signal, green for passenger side turn signal. My understanding is that the round steel plate that the socket itself mounts to the body with, serves as the ground?

With the new wiring installed, the rear turn signals and brake lights worked with the headlights off. But with the headlights on, the tail lights would come on "bright", as if the brakes were on. Rear turn signals would not work with the headlights on (front turn signals work). Then, the brake/tail lights stopped working all together, even with the headlights off. Front and rear turn signals still work with headlights either on or off.

Another somewhat related issue is that when the headlights are on, the instrument panel lights will only come on with the dimmer switch clicked to "bright".

I have installed both a new dimmer switch, and a new headlight switch. The fuse for the tail lights was a little bit too short, so it was barely in contact with both clips. I installed the proper length fuse. I made new connections for the tail light wire both at the firewall, and at the rear where the wiring splits off to go to both sides.

Any further suggestions are most welcome, I'm not very experienced with electrical issues, and I am out of ideas.

 

Don't you just love it when some jerk cuts up the wiring harness? I didn't think so. Anyway, some observations: There are two other switches which can have a huge effect on your lights working - the turn signal switch, which all of your brake and turn signal light wiring goes through, and the brake light switch which screws into your brake master cylinder. Both of these are famous for failing. If you decide to replace the T/S/S, buy a good (more expensive) one. The cheap ones will just be new headaches. You've done well to replace your light switch and dimmer switch, and to install the correct turn signal fuse. Do you know if your front turn signals work properly? You are correct that the tail light sockets should supply the grounds back there. Be sure you have good solid bare metal to bare metal contact. If in doubt, add grounds. Of course, if the lights work then they must be grounded. Did you install dual filament 1157 bulbs? Are they installed correctly? It is possible to put them in backwards. Do they make good contact in the bulb holders? Did you use a little dyelectric (sp?) grease on each one? The brown wire is for the running lights filament (not stop lights) on both sides of the truck, as well as the license plate light. So if things are wired correctly and you pull your light switch **** out one click you should have one filament lit on both sides, front and back, as well as the license plate light. The green wire adds the stop/turn filament for the right rear (it's white/blue for the front right), and the yellow/black wire adds the turn/stop filament to the left rear (left front is green/white). I hope this information is of some use to you. Good luck!

 

Clean all your grounds, battery to frame, frame to cab, frame to engine, frame to bed, bed to cab. Add them if they are not already there. You will be surprised how this can make a difference, electrons flow to the path of least resistance. I once had a John Deere that suddenly started using the choke cable for a ground and melted wires that were touching the cable. Crazy electrons!

 

SuperSabre's response is a good one.

 

Thank you for all of the info! The front turn signals do work properly. I did install the 1157's, but I wasn't aware they could be installed incorrectly so I'll check that. I don't have any grease on the lights, so that sounds like another inexpensive possible solution. I'll try those, then the stop light switch, before getting into the turn signal switch since I'm not immediately finding those at the usual places I've been ordering parts.

Thank you again!

 

Another thing I've done (that I forgot to mention), I've been replacing the ground wires with new ones. The old ones were badly corroded and the insulation was cracked and falling off. There wasn't one from the battery to frame, the negative terminal goes to the starter, then there's a ground from the starter to frame. I replaced both of those and cleaned the area on the frame with a wire brush wheel on an angle grinder. There was also one from the firewall to the transmission which I've also replaced with a new one, and cleaned metal. There aren't any from frame to engine, frame to bed, bed to cab, so that will be another direction to go.

Thank you for the reply!

 

Here is one possible source for your turn signal switch: National Parts Depot, 9th edition catalog, page 174, P/N 13341-2B, price $44.95. Unfortunately, for '63-'64 they call it an "excellent replacement". For '65-'66 a slightly different part number is listed as "original" which really means Motorcraft service part. That's what I got for my '66 and it came in a Motorcraft box. You might call NPD and inquire as to what you get for a '64. Good luck!

 

Don't waste time wth the cheaper ones from NPD (Chinese Knockoffs), call them directly, don't go off of the Catalog or web page... the guys there will explain the "how to" they sent me the Motorcraft for my 64 even though it was for the 65-66 it fit right in, you just don't use the emergency flasher contact

A bad Turn signal switch can really mess with all of the other lights

 

Double contact 1157 bulb cannot be installed wrong, only fits in one way. Bulb has two opposing pins, one is higher than the other. Socket matches pin locations.

C3TZ-13341-B .. T/S Switch / Obsolete / 1963/64 F100/250 2WD

GREEN SALES CO. in Cincinnati OH has 1 = 800-543-4959.

No Ford Dealer, no other obsolete parts vendor has any.
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C9TZ-13341-C (replaced C5TZ-13341-A & B) .. T/S Switch / Ford just obsoleted it / 1965/66 F100/250 2WD; 1966 F100 4WD; 1967/68 F100/350; 1969 F100/350 before serial number D96,001.

CARPENTER NOS OBSOLETE PARTS in Concord NC has 511 = 800-476-9653 / Genuine Ford, cuz DC bought all of FoMoCo's remaining inventory.

 

There's an old saying, "Nothing is ever foolproof because fools are so ingenious." With all due respect to ND, I HAVE managed to incorrectly install an 1157, in spite of the pin location safeguard. All you need is a bit of inattention and a sloppy bulb socket, with a bit of impatient force mixed in. I agree you SHOULD not be able to incorrectly install an 1157, but it is possible!