Brake and Signal Lights Problem

[FORDification]

Just out of curiosity, why not try disconnecting the rear wiring harness completely and see if that allows the front signals to work. If it does, at least you'd know your problem is in the rear harness....which it's beginning to sound like that's where your problem is anyway.

[68F250]

Yeah try isolating the problem.

I don't think the turn signals will flash without the rear bulbs connected, there's not enough load with only the front bulbs but it should light up steady on either side.

Hope you got plenty of fuses.

[skeeterg49]

I had a similiar problem with my '72 F-250. I went to the parts store and bought what I thought was the turn signal switch but it was only the cam used to cancel out the signal. This got me a brake light on the driver side but not the passenger side even though I had turn signals on both. I had to go to my local Ford dealer and have them order my the whole turn signal switch assembly. It cost about $57.00 but you get the whole switch with wires and all. After replacing the old one with the new, my light problems were solved. The guys on here are the ones who helped me to figure my problem out and I know they'll help you get yours as well.

[jcwillis]

Update on Problem:

Did not make much headway over the weekend because of other things going on (Was in LA framing up a door. I live near SF and got back late last night).

Isolating sounds like the best way to go about this. Where is this connector located?

Yep, I went down to AutoZone and picked up several packs of those 14 amp fuses.

Just out of curiosity, why not try disconnecting the rear wiring harness completely and see if that allows the front signals to work. If it does, at least you'd know your problem is in the rear harness....which it's beginning to sound like that's where your problem is anyway.

Yeah try isolating the problem.
I don't think the turn signals will flash without the rear bulbs connected, there's not enough load with only the front bulbs but it should light up steady on either side.
Hope you got plenty of fuses.

[68F250]

Look at bottom of this wiring diagram (sorry for the poor quality) for connector "L" which is for the rear stoplights, taillights, backups & licence. Here's the link: http://www.fordification.com/forum/download.php?id=610

Now look at this cheesy attachment below for the location of connector "L", it is under the hood by the master cylinder. You should be able to find it on your truck, follow the big harness under the truck to where it enters the engine compartment and goes over by the master cylinder. Pull the plug apart to disconnect all power to the rear. Now see if the fuse still blows.

[jcwillis]

Hello Electrical Consultants,

Ok, here is an update . . .

This past weekend, I followed the suggestion by Keith (Fordification) and Barry (69F250) and the flashers worked (only at the front and in dash) without frying the fuse.

Since the only unknown at the rear was the trailer hookup wiring, I disconnected all of it and hooked it up as though it were stock (without the trailer stuff), with only brake/turn; tail, and reverse lights. Flashers still work without popping fuse. But, still only at the front.

Currently (a little electrical humor, ), the front parking lights work as they should (on at first click, off when headlights are on), and the emergency flashers work as they should, but only in the front.

Still no turn signals or brake lights.

Tail lights, front markers on fenders, and reverse lights work.

Flashers will work until I close (step on) brake switch. Then the flasher will stay on steady. Also, without emergency flashers on and with brake switch closed, the dash signal lights come on steady when I try the turn signal each way. Would this be normal?

Although it seems to be in baby steps, at least it seems to be some progress. However, I am beginning to think that the column switch needs replaced as Skeeterg49 suggests, because I only put in the "repair" portion Skeeterg49 initially did.

Does this sound like I would be on the right track?

Jim

[FORDification]

Stepping on the brake pedal WILL overide the flashers, so that the people behind you can tell when you hit the brakes when the flashers are on. However, the signal indicators are still supposed to work when the brake pedal is pushed down, they should never stay illuminated.

Sounds to me like the problem is definitely in the rear harness, or possibly with the bulbs and/or sockets. You never mentioned whether or not you checked the rear bulbs themselves to make sure they're OK. In addition to checking that the bulbs are good, make sure that they're the CORRECT bulb (1157). The 1157 bulb has two filaments....the second filament is what lights up the brake lights and the turn signals. Though it's unlikely, it's possible the second filaments of both bulbs are bad?

If they're OK, then it sounds to me like the power to that circuit is broken. Possibly the wires aren't touching at the brake light assembly harness connector?

Based on what I'm understanding here, I think I'd start from the back and use an ohmmeter and check for wire continuity for that circuit all the way to the front. I'm guessing it's broken somewhere along the line.

[mk]

Jim, I think you're on the right track with maybe replacing the entire t/s switch, if you only changed the cancelling cam in the first place. They are a tricky piece to install right.

mike

[crozetiga]

I had the same exact problem that you have described. I did as you did and changed the rear wiring back to stock (without trailer brake wiring) and it still would work correctly. So I replaced the entire turn signal switch and it work well. I would give that a try. I think the part number is D0TZ-13341-B but someone else might want to confirm that. I got mine from www.carolina-classics.com. It was 57 plus shipping

Josh

[fordman]

i say turn signal switch also. i have problem with one of my rear lights also but my problem is the socket. i need a new one when the cops pull me over all i do is smack the bed and they come back on.

[jcwillis]

Latest Update . . . .

Cliff notes Version:

Changed out the switch assembly in the column, and all of the lighting is now working properly. Nuff said.

Long Version:

I checked out the harness leading from under the master cylinder to the rear by running a hot wire from the battery. Got power through all four wires as the lights worked when power was applied to each of the four wires.

Since wiring to the rear seemed Ok, I hooked up my new column switch assembly directly under the dash (before taking out the old) and everything worked correctly! However, for those who might try this, be aware that the colors of the wires in the switch assembly are not exact matches to the colors in the harness (I would imagine it depends on the year of truck, assembly plant, etc.). For instance, the switch assembly greens were a forest green while my harness green was a much lighter green.

Anyway, so now everything seemed to work Ok when power was turned on and signals actuated, emergency flashers, brakes, etc. Now it was time to put in the new switch assembly. I removed the pins from the two connectors (I used a special tool from Fry's, and needle nose) to clear the way for the new wiring.

I drew up a diagram of which pins go where for the new switch assembly and then removed the steering wheel. I pulled the old wires (all except one wire, happened to be the horn wire, so I could pull the new wiring back down through) out through the column.

I taped together the ends of the new wires in a pencil/spear shape along with the one wire for pulling the bundle, and I found that the bundle could not be snaked back down through the column. After several unsuccessful tries I decided to dissassemble the column by removing the two 3/8 nuts to see what the holdup was.

Wow! What a near disaster. Everything just sort of popped up and fell apart. But, I did find that the wires needed to be in a flattened position (aligned next to one another rather than bundled in a pencil shape) to get through the column shift portion. Reassembly was not too bad once I figured that the two 3/8 nuts, which holds everthing together, had to be extended pretty much all the way before they would catch. With a bit of pushing, jiggling, and aligning, it all fell back together. However, I had to realign the neutral safety switch as the switch had moved while I played with aligning the column to get the column back together.

Took the new switch assembly wires and pushed the new pins into the connectors and snapped the connectors together, did a test of all functions and all works correctly. Granted, the way I did the switch assembly replacement took a lot longer than cutting and splicing in the new wiring. But, it seemed that since the new switch assembly had the pins attached, so it was meant to be put in without cutting/splicing.

Also, while I was under the dash, I swapped out the headlight switch for a new one since, a while back, the dash dimmer spring had decided to pop out of the old switch. Now everything concerning lights for exterior and interior works great.

Next will be to reconnecting the trailer lighting, which likely did not need to be disconnected. Will post about a group of wiring I found in the back frame as another electrical question.

Thanks again to all of you fellow electrical-problem-solving folks.

Jim

[QC]

The brake lights and turn signals are the same filament. If the back ones are burned out the front ones won't blink. The usually will just come on and stay one.

[flyboy2610]

Glad to hear you got it working!