Smoked Christmas Turkey

[speedracer0626]

Well got myself in a pickle this Christmas. I was on the way home and noticed my battery gauge drop out, headlights went dim and she started smoking under the dash. I had just came home and was pulling in the drive so I disconected the battery until the a.m. I started probing with my meter and noticed that the number #11 fuse was grounded. The more I dug into it the more I found. No fixing this harness. Hope I can find one at PAP. Have you guys ever seen this?

 

[speedracer0626]

So did some more digging and found out that I'll have to do some splicing. Question is are all harnesses the same between 4.0 and 5.0?. I have a 98 awd 5.0 and hope to find the same harness but just curious about interchangability.

 

[speedracer0626]

Also while digging I found this GEM. Is this even right? Stock truck never touched until now by me. Is there a difference between the 4x2 and awd Gem?

 

[donalds]

I think just the software is different

Keep at it you're doing good
Solder and shrink wrap one wire at a time

 

[speedracer0626]

So I need to put the right one in it for Awd to function properly? Seems like it has been working fine. I plan on sourcing one Tmrw at PAP for kicks. I anticipate spending my day at PAP getting what I need.

 

[donalds]

Buy one from the same year model as your truck is yours broken

 

[donalds]

Take your sweet time at PAP and get fuses and such

 

[massacre]

Dang dude that sucks
I’ve had a few wires overheat over the years but never saw anything like that!
Good luck with the fix

 

[speedracer0626]

So I spent the day at PAP and got some goodies. Not one truck with the 5.0 had 4wd and there was three plus four 4.0's. Found a sport with the 4.0 5 speed and awd so I grabbed that GEM just for testing. I got the harness out of a virgin 5.0 2wd Eddie. It was late model 97 and mine is late model 98 so I will see what all is different Tmrw. This is the truck I got the parts from. Took me 3 hours to pull the dash and harness. I didn't get but this one picture after I had started tearing it down.

 

[speedracer0626]

So just a little update. First do not cut your body harness unless you like your head in a vise. 2 16g yellow wires for the mirror circuit, 2 for the keypad circuit, and one for the seatbelt. Mirror circuit runs to the back and back up same as keypad circuit. Easy enough just have to trace and mark however Ford made the harness to be easily bolted in and out. Yes I would have had to remove the entire interior but..... A peach in one and an apple in the other. Hey live and learn or go out fighting.

 

[Mbrooks420]

The AWD in a V8 needs absolutely nothing electric for it to function, it’s entirely mechanical.

The 4.0 “AWD” isn’t really AWD, and requires computers and such to work.

The wiring harnesses for the exact year are the same as well. If you pull your radio bezel in your V8 will have a dummy plug infor the 4wd switch wiring, as do the 2wd models.

 

[speedracer0626]

☝ Thank you for the nugget of info on the systems and wiring. I've been doing some research and it appears that there is a model specific GEM for my truck but as you say it's irrelevant.

 

[Mbrooks420]

Kudos for tackling this. I know seasoned mechanics that would cry over less.

 

[speedracer0626]

Door wiring is done and all I have is one extra wire. A BLK/LT BLU for the light in the door panel that is non existent in my Hi Series. Now on to the run under the driver seat and then to the back.

 

[Mr. Alligator]

Awesome work.

But question: what caused all of this? (Read: how do you know that when you hook it back to power, it will not immediately happen again).

Good luck, and good tenacity.

 

[speedracer0626]

Theory on failure. #1 modified relay on the number #11 power distribution feed to under dash relay box. As to why the modification or purpose it served is beyond me. Dealership did "wiring work" because of previous owner complained that her headlights were dim. #2 Ford used an inferior wire that was already taxed from the get go and after 20 years of service one circuit melts into another and you have a ripple effect. Proper repair calls for tracing each wire and verifying proper termination as well as testing to ground to verify no shorts.

 

[speedracer0626]

Case in point. Here we have a low voltage keypad wire in the virgin donor harness. A wire harness that has never been fooled with and as you can see In the picture it's oxidized. So you tin it, crimp it and liquid tape it. My repair will be tucked up high in the kick panel. On the wires under the seat and running in to the back I will use heat shrink butt connectors and liquid tape. The whole harness will be wrapped when all is done and function is verified. The key is to use an aviation crimper with interchangeable dies. This is my first auto wire harness but I have done many of Bell UH-1 restos. So good enough for the FAA is good for me plus liquid tape

 

[speedracer0626]

Also soldering is a bad idea on wire with age and heat cycles. The reason being it takes heat to flow the solder properly thus fatiguing it even further making it brittle. With the vibrations and movement in a vehicle that wire repair could break.

 

[donalds]

I'd solder them don't want to do this again I've been there
All it takes is one bad crimp to send you on a wild goose chase

 

[MAS Tequila]

That GEM IS correct.
I have a 2000 AWD (now 4wd) 5.0 Mountie.