There are 2 fuse boxes on my jeep one under the hood and one under the driver side interior

The under hood 40 amp fuse that powers the fuse panel inside the jeep keeps blowing

when it blows everything else turns on except the dome lights, radio, clock. I replaced it 3 times today. After the second time I took the jeep on a hour long drive to see if anything might blow again and it didnt. Parked and a few hours later I drive to the liquor store. When I get back in the jeep and go to start it up the fuse was blown again.......I dont understand why it would keep blowing intermittently

While cleaning up the battery cables i discovered the brake lights are wired directly to the battery. That doesnt seem to be the reason it keeps blowing but i thought id mention it

When i replace the fuse I can start the jeep and itll run until i turn it off then it wont crank MOST OF THE TIME. Sometimes it will still crank and sometimes it wont until I replace the fuse. Its almost as if it blows when I turn off the jeep. How can i determine when the fuse is blowing?

From what I read its likely a short in the wiring but I dont know what its from because it wasnt doing it until I cleaned up the battery cables and terminals today. Does anyone have any idea what it could be or what I should do ?

Also does anyone have any idea how much it might cost to get this relatively simple issue fixed if i went to a mechanic?

 

If the short was inside the vehicle, it would be more likely to blow one of the lower rated fuses in the internal fuse junction block - before taking out the higher rated fuse under the hood. Because it is the the PDC fuse that is blowing, the two places I would inspect first would be the backside of the PDC (power distribution center / the underhood fuse box) to see if there is corrosion or wire degradation there. The short could be happening very close to that fuse. The second place would be the ignition switch, that is on my mind because of you mentioning that it seems to blow when you turn the vehicle off. It could be the changing of the ignition switch position (when coming out of the run position).

When you blow a 40 amp fuse like you describe, it is almost guaranteed to be a direct short to ground. There are very few components in the vehicle that can pull 40 amps (starter motor, very bad ac/heater blower motor, and perhaps a very bad or stuck seat position adjustment motor).

 

Over the past couple days since attempting to clean up the battery wires and terminals ive had check engine codes for bad alternator, speed sensor and now this blown fuse issue. The speed sensor works intermittently and the alternator was checked the other day and it appears to be working. Once i put a new battery in I no longer get the alternator code.


Today my goal was to clean up the battery terminals and wiring. I cut and striped to fresh wire, wire brushed everything. But in doing all this I did pull on some wires as move the neg. wire around a bit so ill check the grounds along with the pdc.

 

Disconnect the battery before messing with the PDC. Common sense stuff, but youd be surprised how often people dont follow it.

 

can anyone help with where all the grounds are?

I have a haynes manual if anyone knows under what section it might be??


additionally the newest fuse i put in blew again and now i believe it could be blowing on startup and/or when turning off the vehicle

It was blown this morning but the jeep started right up. Just no radio or interior lights

 

Can you take a picture of that and post it? I'm looking at the schematics and I can't find a 40A fuse.

Course I have a white cane, seeing eye dog, bruises...

 

Yeah ill run down and take some pics of everything now.

 

This is showing the splice i put on the positive cables to clean it up. So this is the positive cable from the starter, the positive from the pdc and the brake lights into the one positive terminal

this shows the pdc box. The 3rd fuse from the right is the fuse that powers the internal fuse junction box and its the fuse that keeps blowing

 

Cause dome lights, radio, clock need about 10-15A. See what it says inside the cover re: what SHOULD be there... OK got it.

 

I dont understand. 3rd from the right shows as 40a for fuse block(This is the fuse that keeps blowing)

 

So that thing feeds the inside block. Does the rest of this stuff work?

 

From what I can tell only the following do not work....Radio, Clock, dome light. The cigg lighter works.


One thing I should mention that I didnt before is that I bypassed the stock alarm system the other day becuase it kept activating during startup which was really weird. I bypassed by unplugging it while the vehicle was running and apparently that is a way to disarm it. It is not currently plugged in....kinda just hanging there under the dash. Could that plug possibly be touching something and shorting the fuse?

 

I'd trace the wire from that 40A back to the fuse block. It seems to me that anything else would blow something in the interior fuse box.

Wondering about the brake hot wire. Is that the only mod or are there others.

 

From what I can tell thats the only mod.

Trace it like pull both fuse boxes and literally follow the wire all the way from one to the other?

 

Yes. IMO far more efficient than arbitrarily hunt and peck. Look for any other mods. If no other mods then I'm thinking the issue is near the interior fuse box fuse 1.

Also I'd try to figure out why the brake lights are hot wired. Carefully check the back of the interior fuse box.