I have a 1985 B2 xls, 4×4, 2.8 with 2 barrel carb. I parked it a couple of years ago due to electrical issue. My 15 yo son decided he would like to drive it when he turns 16, so I started trying to figure out what's wrong. To make a long story short, I was trying to get it to "pick up" gas through the fuel pump by turning it over. After 10 to 15 seconds I released the key and there was a puff of smoke under the dash. I unhooked the batt and waited for the smoke to clear. A wire going to the ignition switch (brown w/pink) had nearly all the insulation melted off and a yellow wire under the hood with a fusible link was was the same way. I have found the switch wire on a Haynes diagram but cannot determine what it feeds, so I will know where to start looking for the problem. I have not hooked the batt back up since then so I don't know what all might be fried. Wiring is my greatest weakness, so all suggestions will be appreciated. Thanks in advance.

 

According to my '88 Ford wiring diagram that brown/pink wire moving from the ignition splices out a few times with one lead going to the door sensors and another through the firewall into the engine compartment and to a breakerless module. From that module there are 2 leads back to the starter relay (essentially a direct connection to the battery's positive terminal), another lead to the distributor, and some others. I too was unable to determine exactly what this wire powers, but based on it's direct leads from the battery and multiple splices it appears to be a main power source into the ignition. It's stop along the way at the door sensors seems to confirm that (since the door sensors are 'always hot' not needing the ignition). Considering the wire is melted right at the ignition my guess is there's something past the ignition that's drawing too much current (likely caused by a short to ground) There are a lot of possibilities at this point though. Your best plan of action might be to follow your melted brown/pink wire and just see where it leads you. It sounds like you will need to unwrap part of the harness anyway to replace that wire and you might want to temporarily add an in-line fuse to that new wire until you get the problem sorted out. There's a good chance the melted brown/pink wire is just a symptom of the real problem. A recommended size chart is below.

Found at http://www.bcae1.com/fuses.htm:
Suggested Fuse Sizes
Wire Gauge Recommended Maximum Fuse Size
00 awg 400 amps
0 awg 325 amps
1 awg 250 amps
2 awg 200 amps
4 awg 125 amps
6 awg 80 amps
8 awg 50 amps
10 awg 30 amps
12 awg 20 amps
14 awg 15 amps
16 awg 7.5 amps

If you'd like, I could scan in and upload the related pages from my wiring diagrams tomorrow. They are actually made by ford for their shop tech's so the information in them is very detailed compared to what a Haynes manual might show.

Electrical work just takes a lot of persistence. In my limited experience it usually ends up being a simple problem that takes many hours to find.

 

I did unwrap the harness under the dash and found that the brown/pink wire ran with a red/ light green wire from the ignition switch and joined together and split into 3 red/ light green wires that run to the following:
1. Charge power distribution
2. Electronic engine control (twice)
3. Ignition coil
4. Radio noise capacitor
5. Solid state (not sure what that is)

I am not sure what yellow wire under the hood goes to. I'm guessing the power side of the switch?

Thanks for the help. I will try to keep tracking down wires this weekend and update this post if I come up with anything.