Hi all, Thanks in advance to any who have the time to read and respond. Im working on a 1985 f-250 w/6.9 IHD. Driving along and truck shut down. After further inspection I found a wire coming off the harness (8 wire plug) on passenger side fender well burnt in 2 pcs. Replaced the wire and as soon as I turn the key on, the new wire simply melts the jacket off. Turned key off immediately and started to trace wires, it comes off the connector into a fuseable link then splits off into 2 more wires (one is Green w/red stripe.. other is red with green stripe). The red W/green stripe goes to ignition(guessing here unable to trace far enough) other wire the green with red stripe comes to another plug which has a second wire large yellow to alternator and the green w/red stripe continues to the voltage regulator mounted on fender well. First thing I did was remove and test alternator which tested bad regulator, I replaced alternator and still same prob wire simply melts the jacket off once the key is turned on. I am not getting power to the GPlug indicator light and do not here the glow solenoid engage/click. I guess what im asking for is 2 things. 1st does anyone have a diagram showing destination of wires and volts/amps expected and 2nd does anyone have experience with this issue in the past and know where I should start first. Any and all help is greatly appreciated.

 

Welcome to the IDI Forums! I don't have a wiring diagram so I'm just guessing. Does one of the wires go to the fuel heater? On a 6.9 the fuel heater is the bigger spot on the fuel line that runs from the lift pump to the fuel filter. You have a direct short some place and that is the first place I would check.

 

Not that I can tell, off the fuel heater there is a single wire that goes into the opposite end of the glow harness and that wire on fuel heater looks to be in decent condition. From my guess the system is getting too much juice. Im starting to wonder if A, the voltage regulator is bad or B, the glow solenoid is possibly bad. What I mean by bad is open circuit.

 

Check the actual connection for the thick yellow wires harness. My truck did a similar just die on me. It was the actual plug for the yellow and green wires. The yellow one is the main power wire for the run position. My harness went and the truck just died. I supose if the harness dry rotted or something similar u could get an arc between them and that would definatly melt something. The yellow is main power in run and the green one in the harness with it is a signal wire

 

pardon my lack of knowledge when it comes to auto electrical, but how do I go about checking it? I do know what wires and connector you are talking about, just a touch of insight as to how exactly I should test this. I will say that from appearances it looks to be in good shape.

 

I don't have a wiring diagram either, but you can download the entire Ford 1985 6.9L engine manual here.

 

Artfd TY so much for that, im sure it will be a great help since all I have been able to find are the multi purpose haynes/chiltons (junk) books. Please anyone else with suggestions or info keep it coming, I can use all the help I can get.

 

I remember something like this happened to someone else quite a while back.I believe they bypassed the connector

 

Actually joe f350 would be a good one to assist with wiring issues being he has had about every wiring issue there is. His truck was cobbled up real bad.

 

when got my truck back in Dec. i found my wire like that buy the right battery i guest got lucky ill cut them back and soldering them back to getter there only 1 wire i have no idea where goes but everything seem to and run right

 

Just pull the connector apart and look inside. Anything looking burnt and its shot. I ended up bypassing mine. I cut it out and soldered the wires together. Fixed mg issue.

 

That heavy yellow wire NEEDS to have that connector bypassed. I used a removable butt splice. It offers a very poor connection and creates alot of heat, while running I could mold my plug with my fingers it was so hot. Now if your alternator wiring is in a loom open the loom and ispect the wires they my be shorting inside, mine were full of burned spots.

 

Forgot about the alt wiring mine was pretty beet up as well inside the loom

 

Tackled that before I bothered anyone. If by loom you mean the flexible spliced cover, yes already removed and inspected them. All seem to be in decent shape. I do however recall at one time being told by another guy to just get rid of it before I have any issues. Maybe he was right and I didn't think about that until it was mentioned above. I'm in MO and well, next few days are going to be rather bad with the weather flux we are getting so as soon as I have a decent (not iced/wet) day maybe I will just remove the plug....

Just to be sure we are talking about the same plug/connector. I'm referring to the 8 pole connector (ea side) clipped to the passenger side fender well
oxoo
oooo very bad example of what it looks like and the (x) is the wire that keeps burning on the male side.

 

The only way I could see that causing a wire to melt is if there's a short INSIDE the connector.

I find that unlikely. But I could be wrong. That doesn't mean the connector isn't bad, just means that I don't think it's your issue.

Good luck

-Matt