Archived fuse box fried

[PYoungblood]

I have a 06 3500 4x4 Big Horn. It has the 5. 9 and a Automatic. The truck is stock with 50K miles . When I opened the door today, my blower motor was running in the second to highest position with the key off. I smelled the electrical fire smell and checked under the hood and found the fuse box next to the battery on the driver side really hot. Immediately disconnected both batteries ( which would have erased any codes?) and pulled the fuse box apart. No fuses were blown. The hot spot was up in the corner where the 30 amp fuse for the diesel pcm is located. Melted the circuit board. Has anyone else seen this? If the ignition switch is bad and staying on, why would it have not just drained the batteries? New fuse box is over $700 so I don't want to fry another. Truck still looks good sitting in the drive though. This is my first post but I've seen a lot of helpful reply's on other subjects. Appreciate any help to get this rig running again. Phil

 

[BHanna]

Sounds like a short. Do you have any add-on electrical accessories? I'd check those first. Especially if there's anything added without fuse protection.

 

[PYoungblood]

Thanks for replying Brian. I don't have any add on electrical acc. It should have something to do with the ignition switch powered items but I don't know why it didn't blow one of those fuses.

 

[BHanna]

It could be the ignition switch but not necessarily. This doesn't seem to be a very common problem so I don't know if anyone's going to have a quick solution. It can be fixed with lots of patience though. How good are you with schematics and a meter?

Basically what you need to do is check all the circuits until you find one (or more than one) that's open (close to zero resistance). That should at least narrow down where the problem is. From there you just have to check that circuit until you find the short (that's really where the schematics come in).

 

[PToombs]

A lot of the fuse boxes in this area are corroding the circuit boards. My buddy has an '05 gasser that the lamp out light was on, and the headlights didn't work. Another guy I know with a diesel had almost the same problem. Turns out the corrosion was running right out of the bottom of the fuse box on both trucks. They were on national back order about 3 or 4 weeks ago. The used ones are non existant in this area. My buddy had a used one shipped in from someplace and it was about $250.



You can look right down past the fuse box and and see the ground. All the salt mist in the winter just floats right up into the box. Poor design.

 

[BHanna]

That would explain why the fuses didn't blow. Current going around them instead of through them.

 

[PYoungblood]

Thanks for the input. I ended up replacing the fuse box. While picking up the parts at the dealer I spoke with the service manager and a mechanic who were both very helpful given the fact my truck wasn't in their shop. The mechanic checked the burnt board and schematics and said the problem wasn't in the ignition switch, just a bad transistor or resistor on the fuse box board. Installed the board waiting for a short but nothing has happened. Two days and no problems. Problems like these with electronics and computers make me really appreciate my old '97 12 valve.

 

[JStankus]

This sounds like a possible explanation for the electrical gremlins I have been fighting for a while. I had the problems with the blower running with the key off. (amongst others).



Two questions

(1) how do you disassemble the fuse box to get to the circuit board (it wasn't completely evident when I looked at it today)



(2) I am having a hard time finding the fuse box as a part on the Dodge part websites, what is the part number you used?



thanks



John



2003 Ram 2500 2wd with the electrical Gremilins