Trouble shooting an intermittent electrical problem??

[Scrapper_MV]

My rig keeps blowing the running light fuse. It will go for weeks with no problem, then it will blow the fuse five times in one day. It has a Centech harness that I installed a few years ago. I can't find the short because it doesn't show up when I'm checking. Any ideas on how to find this gremlin?

 

[73stallion]

have you tried a heavier fuse? may be a light bulb that's shorting out. i have a load tester, we could see how many amps the circuit is drawing. not sure if it'll help.

 

[RRRAAAYYY2]

How many legs does it have on the circuit? Try thinking about how and where you routed the wires to each one. Then check where you went through a hole or around and edge. Real PINTA but that is likely where you are going to find the short.

 

[Scrapper_MV]

I tried a heavier fuse, still blows. I replaced all the bulbs on that circuit, still blows. This is the running light circuit, probably the most wire of any circuit! Front marker lights, side marker lights & tail lights. Sometimes it blows the instrument lights as well.

 

[RRRAAAYYY2]

Well you got an issue likely where the wire goes through something, or around something. You ran the wires originally correct? If so you need to think back to where possible rub spots might occur, or where it might be pinched.

When you replaced your bulbs, were any of them darker than the others? If so that is the first leg I would start chasing. Not going to be a fun job. I bought an 8 year old Cadiallac Fleetwood for $400 once because of a wiring short. Took 40 hours to figure out that it was some corrosion on a bulkhead connector.

Nice thing about shorts is they are usually visible. A broken wire is a lot harder to find, so it could be worse. I know you dont think so right now though.