No Electrical Power To Cab

[mulletmobile]

So it’s been a while since my 3G conversion. No problems til today when the boy was on the way to school. He heard what he described as a crackling or electrical sound. Lost all electrical power, engine shut off and he coasted into a parking lot. Now I didn’t have a lot of time to diagnose as I had to get ready for work. What I did notice: Battery had power enough to turn over the motor when I jumped the terminals at the solenoid but engine did not stay running, no power to main cab and it blew two 30A fuses (unk if this was as soon as replaced or when I jumped at solenoid) on the BLK/YLW wire. No other wires appeared melted, burned or scorched. Did not have time to check the alternator or ignition switch. Looking for ideas while I sit here at work tonight planning my attack for tomorrow. Could the alternator/regulator (3G) be faulty and cause this? Bad ignition switch? My MegaFuse is still good I think. Didnt have time to check voltages anywhere yet but I will gladly take any ideas!

[tsherry]

I'm going to be watching this thread with a lot of interest. Planning on several 3G conversions this year.

[mulletmobile]

Wanted to make sure I got back and updated the post. I think I have the problems solved for the time being. Here is what I ended up doing to take care of it.
1) Replaced the previously repaired section on the Red/Blue wire for the NSS where is appeared to have melted insulation and was in contact with the metal housing of the Flasher module. The new wire was soldered in with two layers of heat shrink (glue lined) to help ensure it doesn’t happen again.
2) Replaced the floor mounted Dimmer switch. It was 46 + years old and was feeling crunchy. I suspect may have been part of the issue (is it possible that it hung up internally and allowed the high and low beams to be activated at the same time?) and was old enough and cheap enough for the peace of mind to replace.
3) Replaced the headlight switch.
4) Upon a suggestion by HIO to check my headlight grounds, I pulled both headlights. They both looked ok, but just to be sure I removed them, cleaned with emmory cloth and reinstalled them. While doing so, I happened to notice a cut/crack in the insulation to the LH headlight ground right before the plug. I cleaned the connectors and pinned in a new ground wire.

After doing all of this, the truck starts, runs, and seems to have a better overall charge according to my voltage gauge. My test meter shows 12+ prior to starting and 14.5 when on and running. To help out with the aging wiring, I ordered and just about have a headlight relay harness installed. I will update further when done tomorrow morning.

I do not know for sure what caused the problem of blowing the 30A fuse from the battery to main cab power (Blk/Ylw wire). May have been a snowball that grew, but all in I think I spent $60 between the dimmer switch, headlight switch, and the headlight relay harness. Just a reminder to double check your wiring as these trucks are getting old so wiring becomes brittle prone to problems. Also make sure your flasher module isn’t contacting anything it shouldn’t. Why Ford did not take better precautions rather than letting it swing loose is beyond me. And most important, IF YOU COMPLETE A 3G ALTERNATOR SWAP MAKE SURE YOU HAVE A FUSE BETWEEN THE BATTERY AND THE BLK/YLW MAIN CAB POWER WIRE!! Had I not had this in place I very well could have had a fried truck.