I'm thinking about trying to bypass the engine compartment fuse box. I am looking at using a power source that's hot only when the engine is started or the key is on. Use an inline fuse for 25amp using the pink wire to go to the switch. replace the gray wire completely from the switch to a 15amp inline fuse. Bypass the fuse block and splice in to the light green wire that goes back to the backup lights. I would also leave the trailer connection out of the loop at least until I see if it works.

 

You could do that.

 

Getting close but no cigar. I bypassed the fuses in the box. I turned the key to the on position and put the shifter in reverse and they worked. Celebrated a little to early though because as soon as I turned the key the rest of the way and started it the 25 amp blew. What could cause it to be ok when the key is in the on position but then blow the fuse when I start it? I ran the gray wire from the switch towards the back and put the other fuse in right by the back gate then ran it to the wires going directly to the backup lights.

 

I have a feeling it's the 7 pin plug! I pulled out the pink wire completely and just let it lay on the garage floor while I reconnected it to the power. All of a sudden it works. So, I route it back through the engine compartment again to the same power source i just used and bang it starts popping again. ( Finally got smart and started using a circuit breaker in place of the fuse. ) I am waiting for the new plug to get here this afternoon and hopefully it works because it's an 80 dollar plug. I hope they choke on 75 dollars of it because it's only worth about 5 if that. If it doesn't work I'll choke on the 80. The plug is the only thing I haven't replaced. I have even bypassed the fuse block under the hood with my own wiring and inline fuses. Plug is supposed to be here in a couple of hours. I'm gettin the beer cold! it better work.

 

You definitely have a short in the wiring somewhere. Hopefully for your wallets sake, the trailer plug is the source of the problem, but it is strange that it would pop the main fuse even with the TRL B/U fuse out...

 

I installed the new 7 prong plug and here's what I have. I turn the key on; in park the fuse blows, in reverse the backup lights work, in 1,2,3 or drive the backup lights are off and the fuse is OK. Park is blowing the fuse. I have six wires going to the plug so I have one left over. If only six are to be used, Do you know which prongs are supposed to be used?

 

I think it's time for you to get a hold of a factory service manual or AllDataDIY.com account and start pouring through the wiring diagrams, isolating circuits, and testing for shorts, etc.

Wiring problems are tedious and painful to chase down, but once you start cutting into the system and rewiring things, it becomes very difficult for us to help you.

 

I have an alldatadiy account but it doesn't give me the detail in the electrical schematics to see this. I can read any kind of a print or schematic with one eye tied behind my back but I need the darn thing first. I even went to the dealer to get some info but they only gave me what I already have.

 

I have never found a schematic for the park/neutral switch ever. If you replaced your switch, maybe you could cut the old one open and snap some good pictures of what's inside for all to see. With some pictures, I can create a schematic.

What else are you not seeing in your Alldata account?