Traceing a short ????

[Dandeluxe]

My 69 chev. cst p/u keeps blowing the fuse for my tailights and interior lights ..It only does it after about 20- 30 minutes after driveing ..It seems like it has to get warmed up ..I'm pretty sure it is in my dash lights panel but i could be wrong. My ? is how can i trace this back w/ o going nuts . I plan on installing a new painless wireing harness soon but don't have the cash flow and would like to drive it to get my doors and hood painted. and to get other work done .. any help at all is greatly appreciated and thanks in advance for any help .. thanks, Dandeluxe

[cdowns]

it's easy to inspect the taillight harness you get on your back crawl under the truck with a light and look at the harness inch by inch and use your fingers to feel if theres cracks in the insulation especially where the harness is held by clips to the frame rail// if you dont find anything there repeat procedure under the dashboard

[Dandeluxe]

Thanks!!! I Will Try That C Downs

[gator2511]

If you don't find it you can always splice an inline fuse in the wiring leaving the dash. Size the fuse one amp less than the fuse panel fuse and see which one blows. If the fuse panel fuse blows its probably in the dash. If the fuse in the wiring leaving the dash blows you have a problem farther back towards the tail lights. You can move it all the way to the back in between the lights to see which one is blowing the fuse. If you don't have a short all the time thats one way of finding it. Tom

[67chevy2wd]

Start unpluging things too and see if the fuse still blows. For example unplug the tailights back at the rear crossmember and see if the fuse still blows.

[Dandeluxe]

Thanks guys, I am considering going with this idea on the problem..
http://www.itsasnapwireandcable.com/new_page_6.htm

[Old Yeller 1970]

I agree with cdowns, I'll bet your problem is in the taillight harness. I had the same problem which turned out to be where the harness split off and went to my trailer light connector. One of the wires was laying on a brace in my bumper and shorting out where all the insulation rubbed off. Since then I've removed the entire taillight harness and replaced everything from the firewall back to the taillights because all the insulation was dryrotted and peeling off.

[Dandeluxe]

Thanks !!! i'll try these suggestions

[dwaite72lnghrn]

I had my taillights blow fuses and put a new ground between the frame and the bed near the back and no more blown fuses. You get too much resistance in the circuit and pull too much current and blow the fuses. Run a 12 gauge wire between the rear frame driverside and the rear cross member of the bed holes are already there on mine, scratch the surface good before you put the wire on tighten them down and then paint them.

[ND_guy]

Originally Posted by dwaite72lnghrn

I had my taillights blow fuses and put a new ground between the frame and the bed near the back and no more blown fuses. You get too much resistance in the circuit and pull too much current and blow the fuses. Run a 12 gauge wire between the rear frame driverside and the rear cross member of the bed holes are already there on mine, scratch the surface good before you put the wire on tighten them down and then paint them.

Bad grounds are a source of many problems and a good thing to keep an eye out for but,
Amps = volts divided by resistance

So more Resistance= less amps

[dwaite72lnghrn]

ND_guy I agree but when you have a bad ground and the current goes from 13amp? (bad ground) to 20 amps? (good ground) fuses blow(rapid current rise). Just my experience bad ground on rear lights blows fuses. The other thing that will cause fuses to blow is dirty or corroded fuse block. Increased resistance causes heat at the fuse and melts the fuse. check and see if the fuse block is hot. again just my own past experience.