I have a 97 dodge ram 1500 5.2L 2wd 5 speed manual transmission. Truck has 125,000 miles and I'm the second owner. Wiring on this truck has been a nightmare. I have got the truck back up and running mechanically, only problem now is my brake light fuse keeps blowing intermittently. I've been chasing wires for 2 months of weekends now and I can never repeat the fuse blowing unless I'm driving. I've tried shaking every wire and jumping up and down on the truck and it won't blow. It did have a horrible trailer light job done which I have already taken the wires off. I've replaced brake light switch just for good measure.

Tail lights work
Turn signals work (although I just found last night that the previous owner had a 20amp fuse instead of 15 amp fuse installed in the fuse box in the cab)
Brake lights work when fuse isn't blown.
Center high mount brake light works when fuse isn't blown.
Hazards work.
Once fuse blows brake lights and 3rd brake light go out everything else still works.

Any advice would be much appreciated.

 

Do you have a trailer light connection? I'd pull that apart and check the wires first. Something is shorting to ground and this is the easiest section to check.

 

It did have one but I have taken it all off due to poorly being done. Exposed wires were just twisted together. Currently I have just temporarily wrapped electrical tape around the exposed wires to track this problem down. Eventually it's going to get completely rewired with new sockets for the tail lights.

 

Definitely look there to begin with. If those wires are messed up, you probably have other issues in the same area. Unfortunately, whoever did it probably worked on other places too.

 

I'll definitely keep looking. But let's say that checks out. Been reading on how these trucks are wired and I get different information from some sources and it gets a little confusing. Brake light wires from the fuse box go to the brake light switch then splits to the multi function switch and directly to the 3rd brake light, from the multi function switch it goes back to the rear of the truck to left and right brake lights and turn signals.
So if a short to ground happens anywhere in that system the fuse will blow and no brake lights will work, not even 3rd brake light, am I right?

 

Check inside of your trailer plug if you have one.

 

Trailer plug and all trailer wiring have been pulled from the truck.

 

I think so. I'd check the wires where they run along the frame. Look for some place where it rubs. You may have an intermittent short there.

 

Alright that's what I was afraid of. Inspecting every inch of wire from front to back. Looks like I'll have to pull all the wires out from the looms and see what I can find. I was hoping it was just the trailer wiring.

 

Look for a shiny spot on the frame metal. That's probably where it's rubbing. If that doesn't work, look for a damaged spot in the loom. Look for something that doesn't look factory. I had a Furd F-150 that was a nightmare until I found a spot with the loom damaged. It had several bare wires in it. A couple of hours of rewiring and my problems went away.