Wiring problems on 89 F250 diesel
 

Ahoy people. This is my first post. Unfortunately I had to look for this site because I'm having an issue that's difficult to resolve. Saturday afternoon returning from work my truck crapped out on me. I hadn't even made it a block when the engine, radio, air conditioner, and everything shut off like I had turned off the key. The clock on the radio worked and the lights worked when I turned them on, but turning the key did nothing. So I replaced the ignition switch but that didn't fix it. I grabbed a voltmeter and started probing and the battery wire for the ignition switch had no voltage. That wire is supposed to always be hot. So I hotwired it by running a wire from the battery terminal straight to the ignition switch and everything worked then.

So I need to figure out where that wire goes to know where to check it. I checked the fuse links next to the battery which were fine but I don't know of any other fuse links or connectors that wire may go through. I have the official Ford service manual but it doesn't show detailed wiring diagrams. I could use something like the Hayes repair manual I have on CD for my 94 Thunderbird but they don't seem to make them for an 89. If any of you guys could tell me what to check or provide a wiring diagram showing all the fuse links, connectors, etc, that would be awesome.

Nobody? Surely I haven't baffled everyone.

This would probably be better asked at www.12volt.com they have all kinds of wiring diagrams and will most l;ikley be able to help you out.

Here's the schematic for a 88 F250 diesel. Hopefully the 89 is the same.
The ignition switch gets 12 volts from a yellow wire that is hot all of the time.

The Battery has a Red wire that connects to one side of the Starter Relay.
On that same lug are a bunch of fusible links. That is where the Yellow wire comes from.

Looking at the schematic, there appears to be at least 3 Yellow wires going to the Starter Relay.

They all appear to be on Circuit 37 so I assume they are all on the same fusible link.

1) For exterior Lamps, Trailer
2) Provides 12 volts for Fuse #1
3) Provides 12 volts to the ignition switch

http://i135.photobucket.com/albums/q...0xlt/PG022.jpg

http://i135.photobucket.com/albums/q...0xlt/PG020.jpg

That wiring diagram is quite helpful. Can you tell me where C100 is? Is that the connector in the firewall?

And from where did you get those diagrams? They're like the ones I have on the CD-ROM for my car, but the manual for my truck doesn't have them. It'd be nice to have such a guide for the truck too.

The manual only says C100 is a 53 terminal connector that goes thru dash.
LH side.

This info. is from the Electrical Vacuum Trouble shooting manual.

For the 88 F150-350 there were two Book type service manuals.
Truck Shop Manaul A and B.

You could also purchase the Electrical Vacuum Trouble Shooting manual
Engine Emission Diagnosis manual, Light Duty Specifications Book, Owners Guide and Schematics. The schematics I got were copies and if folded out are like 2ft x 2ft and very hard to decipher due to the way they label the pages. All of these documents were published by http://www.helmsinc.com

The company is located in MI and publishes the service manuals for Ford and GM.

Not sure on an 1989 Truck but on a 1989 E-series in the wiring harness about a foot or so from the firewall connector in the engine compartment there is a group of four fuse links sticking out of the wiring harness. One of them is a large yellow wire.
I have not seen this on a 1988 van so the 1989 truck may have these fuse links also.

A Photo of them:
http://i54.photobucket.com/albums/g9...onFuseLink.jpg

Then yeah, it's that connector at the firewall I was talking about. It's where all the wires go from the engine compartment into the cab.

That explains it. I have manuals A and B, but not that troubleshooting manual. I'll have to see about getting that. It has been so helpful with my car.

I'll look for that. I'll bet there is one. It would be highly unusual if the wire itself went bad.