Fusebox disassembly - Diesel Forum

tinman13kup · 12-09-2012, 06:29 PM

I thought I had sealed my leaking windshield, but after a couple days of rain I learned otherwise. I figured I would take some pics of how and what to expect if others have to do this.

My initial issues in the past were

fan not turning off
pcm/fuel pump relays chattering with key removed
truck not shutting off after keys removed

My latest issue came the other night, when the horn started blaring in the middle of the night. I disconnected the horn and soon after, the interior lights would come on while driving and the horn relay would go crazy, so I decided to dry out the fusebox.

Here's the steps and pics of the fusebox from a late model 99.

disconnect the batteries. easy enough
for me, it is easier to use a rod and jam the clutch pedal down and remove the dash panel. It allows easier access to the 2 big fusebox plugs on the rear and the 10mm bolts that you must unscrew.
remove both harness plugs and the gem connector
remove 2 upper bolts and 2 lower 10mm nuts holding the fusebox to the dash.
maneuver the box and pull it out.
I removed my relays, since they are easy enough to remember where they go and get in the way when removing the box
take a picture of fuse locations and sizes
on the rear, you will need to cut the flanges off the bolt posts. They keep the whole unit sandwiched together. Mine were removed with a dremel tool. Notice the rust in the bottom.
Next, pull the 3 torx screws out that hold the gem on and remove the gem.
The 2 halves can be separated now. Pop the clips around the perimeter and slowly work the back cover off, keeping the baskside facing upward. Keep the 2 halves parallel to avoid bending pins. Once they are separated, there might be some loose traces on the front half. They go from the harness connectors straight to the gem connector. I just transferred them back to the rear cover.
Now you should be looking at a black tray with pins coming out for the connectors. Using a small screwdriver, reach into the holes around the outside edges and start working out the tray pack. There are 5 layers, and there are pins out the frontside that go to the fuse locations. Here is the inside of the front cover after all trays were removed. The fuses are still being held in by a double female spade connector from the front. I see lots of rust and moisture.
separate the plates slowly and lay them in order. There are little clips that hold the traces in their locations, and each trace sits in an indent. They will stay in the tray as long as you separate them evenly and slowly
It's not hard to understand why circuits were shorting together in this pic.
I used silicone spray and sprayed and wiped each layer and put it back into the front half, one at a time, pushing evenly and looking to make sure each pin is getting into it's slot. If you didn't bend the pins, it goes together easy.
Before putting the rear cover on, a quick cleaning with some silicone and a nylon brush in the dremel was in order.
snap the rear cover on and mount the gem and it's ready to put back in

This took about 5 hours, with a 2hr break because of rain

01f25073 · 12-09-2012, 10:33 PM

Thanks Tom. This is why I like this site so much. I have a folder on my computer that is full of topics just like this that saves me from going to the dealer (if I have the same problem). I just replaced my GEM this past summer so the pictures look familiar. I am happy for you that you solved your issues and thanks again for posting this thread.

grandpawj · 12-10-2012, 07:00 AM

+1 Thanks Tom