Keep Blowing My Signal Light Fuse!!!

[Propanator]

I bought a 69 f100 last month and I cannot for the life of me get my signal lights to stop blowing the fuse. I can put a new fuse in and turn on either signal light and it will go forever if the truck is just sitting there (running or not), but as soon as I pull out and take it for a drive, the fuse goes. Sometimes it goes even before I turn the signal lights on and other times I can drive with the signal light on for 3 mins, turning it on and off periodically and letting it cancel when I turn, then it blows. If ANYONE has ANY info that may be helpful, it would be much appreciated.

[PhantomoftheBumpside]

Possibilities...

1. Incorrect fuse?

2. Intermittent short somewhere or extra crap wired in wrong. Trace the wires and make sure there are no bad spots that could be occasionally making contact to the body/frame, and that extra stuff isn't wired into these. These wires are are white wire/blue stripe (right side circuit) and green wire/white stripe (left-hand circuit).

3. Wrong bulbs. Make sure you have all 12V bulbs and not 6V or 24V, incorrect size will mean the wrong draw and you may blow the fuse instead of the lamp(s).

[Propanator]

Thanks for the reply PhantomoftheBumpside.
I checked both the bulbs and the fuse and they are correct. I have been following wires and they seem to be fine as far as I can see. I just don't understand why everything is 100% until I actually take a corner. I thought that might just be because the battery couldn't supply enough amps to blow it, so I fired it up and revved it up to 2 or 3 grand and the fuse was still fine. Nothing goes wrong until the truck moves. I'm kinda baffled.

[PhantomoftheBumpside]

Front and Back?

At the firewall?

Near what's left of the battery tray ?

Metal conduits behind the taillights ?

[67mann]

Just a thought...as I'm not to informed on this whole wiring thing but you say "until the truck moves" nothing goes wrong.....so I'm thinkin it may be in your steering column. You made the statement of turning and it blows....Try starting your truck...turn your wheel left..check..turn your wheel right check

It's sounds like you have a short in the harness inside the shaft

[basketcase0302]

I'd 2nd the column possibly being the culprit here. There should be a ground strap that ties the two halves of the "rag joint" together, (goes from one side of the steering coupler to the other). There's pictures here somewhere that show that "ground strap", but I can't seem to find them now...
I'd also go to each turn signal bulb assembly and verify the grounds there are good with an ohm meter.

[70_F100]

Column "could" be the problem.

Ground strap won't make a difference, though. The TSS will work fine just hanging out in mid-air. That ground strap is just for the horn.

[67mann]

[Propanator]

Hey looks like I may have found the short... or I am closer anyways. I decided to just unhook each component downstream of the fuse them plug them back in and drive it one at a time until I figured out which component was blowing the fuse. Turns out it is the back up switch or on the way to it. So I now have signal lights!.... but no back-up lights. That's a bit of progress though.... kinda. Thank you for the replies guys.

[basketcase0302]

What transmission do you have (to maybe help locate the switch if you don't see it)? If memory serves me correctly the two wire harness for the back up lights runs down the DS framerail on it's way toward the switch mounted in the tranny. I'd run a continuity test on the switch itself also. With the engine off / have someone shift it into reverse (where you'd have continuity across the switch) / no continuity-when not in reverse.