Parked in the field and when I started to work on it today noticed this wire chewed off.
Engine started and ran fine to move to driveway, anyone know what it is for? Comes out of the glow plug loom to this Junction Plug then ends……
Thanks for any help.

Craig

 

looks like one of the glow plug power wires.

 

If it was clean it would be red with light green stripe.
On 1987 and earlier, that wire goes to the Fuel Line Heater which is on the upper part of the steel fuel line coming up from the lift pump to the filter assembly. The heater is cylindrical shape, about 6 to 7 inches long. You'll see it. It has a single wire coming out of the bottom of it and that's the wire you are holding.

Be careful with that connector and don't try to separate it, they are very brittle from age and heat and will crack/break.

In the other direction: On the harness side of the connector the wire will look black but it's actually Dark Blue. On my 87 that wire goes into the harness and it runs inside the harness conduit to the engine side of main 8-wire harness connector (plug) on the fender well - that's the female side. It goes to the pin location that I have marked with an 'X' (Y = the two main power wires to the Glow Plug Relay and on the starter relay side of that harness connector those wires should be Black with Orange Stripe going to the starter relay on the fender well)
Female (engine side) of main harness connector on fender well:

Y O O O <---top row
Y X O O <---bottom row

On the male side of that 8-wire harness connector that wire goes to a 20 GA Fusible Link, then, with another different blue wire and fuse link (from a different pin on the 8 wire harness connector) it is spliced into a single larger red wire that goes past the start relay and into the main harness that runs in front of the passenger side battery. It probably goes to the ignition switch via the fuse panel.