Fuse For Turn Signals Keep Blowing

[hdunlap]

I have a 1971 F-100, 351 Windsor (transplant), C-6 Automatic Transmission. I must say that for many years I have enjoyed owning the truck and it is fun to drive. Also I have enjoyed my almost daily visits to the forum and I have learned a lot from the different posts on the forum. For some reason my turn signal fuse keep blowing. Things I have done so for: traced the wires looking for bare spots, cleaned the turn signal bulb sockets, replaced the turn signal switch, replaced the blown 14 AMP fuse and all is good (all lights work as they should) for 20 minutes or one trip around the block before the fuse is blown again. I know this subject has been discussed on the forum before but I haven't seen a post that indicates what was done to fix the problem. After a lot of wire chasing looking for frayed wires that may cause a short and replacing fuses I have ran out of options and have no idea what to check next. Please help
Thanks in advance
Hdunlap

[Nitekruizer]

I'm not saying that this is what's wrong with your truck but it did happen to mine. When I bought my truck, sometimes it would blow the Turn Signal fuse too. The windshield washer and "back up" lamps are on the same fuse. I notice that you have a C6 so, this may have already been ruled out. Anyway, my truck had "three on the tree" and the Back Up lamps were not hooked up. There's a little two prong connector under the hood. In my case, it just kind of dangled from the wiring harness and at certain times would make contact with the sheet metal or some other metal part and cause the fuse to blow. I tied it up so it couldn't touch anything and no more problem after that. It's a longshot but, I just thought I'd mention it just in case.

[hdunlap]

Nitekruizer, thanks for the info, I will check that out soon as I get home from work. I got my fingers crossed that your recommendation solves the problem. I really miss driving my truck. Hdunlap

[tac]

You might want to take a look at the rear harness where trailer lights were connected creatively by a PO. Bare wires stripped back to tie in a trailer or trailer harness just cut off and left dangling.

[hdunlap]

Nitekruzer
I'm not saying that this is what's wrong with your truck but it did happen to mine. When I bought my truck, sometimes it would blow the Turn Signal fuse too. The windshield washer and "back up" lamps are on the same fuse. I notice that you have a C6 so, this may have already been ruled out. Anyway, my truck had "three on the tree" and the Back Up lamps were not hooked up. There's a little two prong connector under the hood. In my case, it just kind of dangled from the wiring harness and at certain times would make contact with the sheet metal or some other metal part and cause the fuse to blow. I tied it up so it couldn't touch anything and no more problem after that. It's a longshot but, I just thought I'd mention it just in case.

After a really good cleaning of the wires from the two prong connector I found a tiny, very tiny bare spot on one of the wires that was I guess every now and then rubbing against the brake line creating a short and causing the fuse to blow. Thanks again to the members of this forum (Nitekruzer in particular) and some electrical tape another problem is solved.
Hdunlap

[laharve]

Just happened to me, funky battery box by P.O. slides forward to pinch off the right front blinker wire causing a short to ground were the wires feed through the raidiator support (kind of a jagged edge formed by the punch press from the front toward the battery) . Because turn signals, emergincy flashers, brake lights all work off the same fuse, all are off. Fix replace wire and better secure battery and all are good.
Any body know how to check the flasher unit itself?

p

[hdunlap]

Wish I could help you with your question ref testing the flasher. Hopefully someone will come along soon with an answer. My fix for that is to keep a few flasher on hand and change them out when I think the flasher my be the problem.
Hdunlap

[tac]

Just happened to me, funky battery box by P.O. slides forward to pinch off the right front blinker wire causing a short to ground were the wires feed through the raidiator support (kind of a jagged edge formed by the punch press from the front toward the battery) . Because turn signals, emergincy flashers, brake lights all work off the same fuse, all are off. Fix replace wire and better secure battery and all are good.
Any body know how to check the flasher unit itself?

p

You can test a flasher by connecting it in series with the brake light bulb across the battery.

[fordman]

Our trucks have two flasher cans. Swap them. To test.

[ricotesio]

I'm having the same problem. My lights won't blink. They just stay on constant when I try to use them. I replaced the fuse tonight and they worked for about 30 seconds before going back to not working. I tried replacing the fuse again but it never worked again.
I am extremely new to this and have no experience in automotive repair. Trying to teach myself everything I can..
It's my best bet tracking wires and see if there is anything obvious?
Thanks in advance for any advise.

[fordman]

I'm having the same problem. My lights won't blink. They just stay on constant when I try to use them. I replaced the fuse tonight and they worked for about 30 seconds before going back to not working. I tried replacing the fuse again but it never worked again.
I am extremely new to this and have no experience in automotive repair. Trying to teach myself everything I can..
It's my best bet tracking wires and see if there is anything obvious?
Thanks in advance for any advise.

Spunds like the element inside one of the bulbs is broken and shorting.inside the bulb.