Hi, as mentioned in the title, when the brake is depressed the passenger brake light illuminates appropriately, whereas the driver's taillight (with parking lights on) goes out when the brake pedal is depressed...no light. What the heck?!

This is on a '78 F-250 Camper Special. I'm new to these trucks (only owned it about a day) so any assistance is greatly appreciated.

Thanks!

 

This sounds like a ground issue. 9 times out of 10, the problem is in the socket itself, meaning replacing the socket solves the problem. It's strange that it goes out completely, however, instead of dimming (which is often the case). You could verify this by probing the socket terminals with a multimeter while a buddy works the brake pedal - if you see something like 2 or 3 volts (or anything much less than 12) at the socket with the lights on and the brake pedal pressed, that would point to a ground issue. However if you see no voltage at all, then maybe it's a little more complicated.

 

I've had a problem similar to this on 2 of my trucks, no driver side brake light, replaced bulbs, socket, some of the wiring and couldn't figure it out until one night I was messing around with the turn signal switch and I noticed it was coming on if I pushed it up! I never fixed it, I would just hold the switch up at stop lights but I figured it was the switch inside the steering had gotten worn out, napa sells a repair kit for $17 online, maybe cheaper at your local store or replace the whole thing for $59

 

I've got a similar issue on my 75 and glad to see some comments. Maybe it is related to the turn signal.....hmmmm.

I had the problem with the driver's side, too. Grounds look fine. The running light in the rear DS tail works, but not brake or turn signal. I cleaned the socket and it began working. But when it recently went out I replaced the socket with a new one, but it still doesn't work.

I'll look into the turn signal switch. Any other suggestions are welcome.

 

just back up to a wall and put your brakes on and play with your turn signal, if it comes on then it's probably your switch, mine was a total accidental discovery as I had my truck backed in and I was doing something else to it and noticed my light coming on when I just slightly pushed it up

 

What is the deal with these ground issues all over the place?

I'll look into what you've mentioned, fmc400. If that's not it, where is this switch you're talking about, Ace.? What did you "hold...up"?

The previous owner mentioned that he thought it would be something to do with the harness for the trailer lights (a ground or something). Would that make any sense? And if so, how would I go about checking an fixing that?

I haven't actually opened it up yet, but where are the grounds that I need to be checking on all of the sockets? Maybe it will be self explanatory once I'm in there.

Is there some kind of prevtative maintenance that can be done so as to not continually run into these problems?

 

the switch is actually under the steering wheel, but I just held my "turn signal bar" (for lack of having a few beers, and little words) up

whole thing
Store Locator | NAPA Online

repair kit
Store Locator | NAPA Online

 

don't know why it says store locator, but I clicked and it actually takes you to the parts I'm talking about

 

Great, thank you!

I noticed that the replacement has a hazard switch on it. I don't see hazards on mine. Did '78 F250's have hazards?

And how difficult is it to access this piece (that you linked to above)?

 

I actually had this same problem on my '78 F150. You have to pull the steering wheel off, but that's the hardest part of it. I was lucky enough to have bought a steering wheel puller a number of years ago for another vehicle; you can rent them from one of the auto parts stores (Auto Zone? I don't remember which one it was; I was going to rent one, and they told me I could buy one that had been used for the same price. They then found out they had no used ones, so I got a brand new one for $20).

After that, you take 4 screws out of the plastic piece around the lower part of the steering shaft, holding it onto the dash; 3 screws from the switch itself; and disconnect the wiring harness under the dash. The wires should then pull out.

As for the hazard, look on the bottom right of the steering shaft. I would think your truck had it.

 

Ground Everything!

Check your ground from your battery (-) to the chassis. (See photo)

Check your ground from your battery (-) to the engine block.

Check your ground from your block back to the chassis. (Usually behind the carburetor on the intake manifold to the firewall.

Fix as needed all the above.

Then install an additional ground on your rear wiring harness near the rear fuel tank. Determine which wires go to ground by using a multimeter or a test light. Once you found the ground (Common wire) ground it to the chassis but don't cut it off, just loop it to ground. Use all industry practice when doing this procedure such as wire brushing the chassis, using proper guage wire etc... Mine was easy because someone wired a trailer harness connector so they already spliced everything so for me it was just a matter of dressing it up and adding a ground strap.

I had dim dash lights, turn signals that didn't work properly, tail lights that where dim and a plethera of other strange electrical issues. I did these repairs and all my strange electrical problems went away. The photos show my ground strap on the rear harness and my chassis ground from my battery.

 

Hazard lights were federally mandated in the 60's. Yes your 1978 is supposed to have hazard lamps. It sounds like you need to replace the turn signal switch. It's obviously broke if the hazard switch is missing, however it may or may not be your initial problem. Brake and turn signal lights go through the hazard and turn signal switch. First step in diagnosing the turn signal switch for faults in the service book is to turn the hazards on. No hazards, replace the switch and then test again.

Hope this helps.

 

Ok, so the previous owner told me that it did not have hazard lights. After reading these posts I checked with a flashlight. Lo and behold, HAZARDS! I tried them and they work fantastically. I guess I need to play around with the turn signal lever while depressing the brake. If no indications there then I'll open up the taillights and play around with the multimeter to see if the socket is bad. Following that I'll check the grounds on the rest of the vehicle.

Does that sound like a good plan?

NBC-Steve, do you know what "industry practices" are? I have a few different trailer harnesses in the back. Can I ground one of those to the frame? Did you have to tap threads, or is there a nut on the other end of that bolt? Lastly, did you just use one of the splicing connectors to connect to the ground and run a wire from that to the chassis (if that makes sense)?

 

so all 4 corners of the truck light up with your hazards on?

 

Yes, all four corners light up. The strange thing is that when the parking lights and hazards are on at the same time the rear hazards flash opposite each other, and the passenger side parking light (taillight) is on, while the driver's side is off.

Additionally, I just noticed that the left-hand turn signal works just fine...unless the parking lights are on. Once the parking lights are on it either stops working (stays dimly lit when it's supposed to be on), or is very very sluggish. But the indicator on the dash is very dimly lit at all times that the parking lights are on.

Glad I found another clue...wish I knew what it meant. lol