Main Wire Harness Pics

[icanfixall]

After removing the passenger side battery I found a melted fusible link. Its on the heavy yellow line from the fender solenoid. I followed the wire to the corner of the battery tray and then it goes across to the drivers side and into the dash thru the large round plug. the actual link says 18 gauge and it ends up connected to a large yellow wire. Can anyone post a wiring schematic of this under hood harness. No idea what I'm doing in this mess. The heavy wire lug has 4 smaller wires with the fusible links after it.Found a red wire and a black or maybe blue wire. Most are 20 gauge fusible links too. Thanks for any help.

 

[franklin2]

This is supposed to be a 89 diagram

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89 truck wiring 1 by D Franklin, on Flickr

 

[franklin2]

One fat yellow wire goes to the fuse box(hot all the time parts of it) and the other yellow wire feeds the ignition switch.

 

[ifrythings]

http://www.bbbind.com/tech_database.html

This site has all the wiring diagrams, just put in some bogus stuff to get past the first screen and they have everything in pdf format

 

[Clb]

More info on this^^^ please.
Gary
I have an 88 fsm if it helps

 

[icanfixall]

Well no joy in my search for why the fusible link burned. As posted.. It appears to be the yellow wire leading to the trailer lights ect but it may also go to the fuse box. So today I will remove the steering colume and see what the top of the fuse box plus what the headlight switch looks like.Did I say I hate electrical problems...

 

[laserjock]

Gary, if you are going to have to replace the link wires anyway, cut the link out to separate it from the group then jumper each one individually, see what works (which one is which) and then go searching from there. I wouldn’t pull the column until I narrowed things down a bit.

 

[chillman88]

It appears to be the yellow wire leading to the trailer lights ect

Check your trailer relay if you have one. Mine was corroded and kept powering my fender lights (dually) until I replaced it.

 

[icanfixall]

Good points about testing before removing the steering column. I have not found a trailer lights relay but I have not looked for one either. I have a Teconcha brake controller I use for the trailer brakes

 

[chillman88]

Good points about testing before removing the steering column. I have not found a trailer lights relay but I have not looked for one either. I have a Teconcha brake controller I use for the trailer brakes

If you have a trailer relay it should be somewhere near the drivers side hood hinge. I'll snap a pic later. I don't know where it's "supposed" to mount because mine was just lying on the inner fender until last week when the lights stuck on and I pulled it apart and blew the water out of it before zip tying it upright.

 

[icanfixall]

Well no joy today. I looked at the fuse box back side.. No burns. I replaced the ignition switch. No change. Kept blowing the 35 amp inline fuse I installed on the red with green strip line to the cold advance and the fuel shutoff solenoid. BTW I replaced the top of the injection pump where both solenoids are. No change. So I removed the glow plug solid state controller. Engine starts after some cranking and no burned out inline fuse. So just purchased a new dy1128 motor craft controller.Be here by the 9th... Everything works. Turn lights. Headlights. Flashers only work on the back tail lights. Gotta look into that later. Probably a fuse in the box under the dash. Sure is a ****** not "finding" a smoking gun problem. Damn....

 

[laserjock]

Have you deleted your fuel heater Gary?

 

[OLDBULL8]

Do you still have the OEM Alternator with the regulator on the fender, or has it been changed to the 3G?

Why are you just throwing parts at it? Deep pockets?

Find the source of what burned out the fusible link.

 

[icanfixall]

Did away with the alternator with fender mount regulator 10 years ago when I rebuilt my engine. At that time I changed to the serpentine belt drive so I ungraded to a large 180 amp alternator.
The fuel heater has been disconnected and taped off for many years also. The ONLY electrical item still connected to the red w/ green stripe wire is the cold advance and the fuel shutoff solenoid. Both of those have been replaced with spares I had. I might have the same color wire going to the solid state glow-plug controller too. Am now opening up that wire harness. Had to rest. This old body hates bending over the engine with my feet in the bumper air vents I cut bout 20 years ago. Not sure if they work better as sets or air vents to the lower radiator. It does get me up high enough to work leaned over the engine. Just working way in the back sucks. Old body and failing heart can't work like last year.

 

[icanfixall]

So after looking at everything in the main engine wire harness diagram I see the ONLY thing I have not looked into.the coolant switch has not been "looked at". Its the small black box hidden down low behind the thermostat housing. The wire in question goes into this. May "find one" in the local wrecking yard and try it.Mine is factory so its been working since 1989.