Rat damage to dash wiring
In case other folks have rat damages under the dash, here are some suggestions
I did all the work with the loader in place, it really makes things difficult to get to the front of the truck. I expect it would be worth the effort to remove the loader which would open up access significantly. You will need to get at the wiring at the back of the dash and that means you need to remove stuff. First thing to do is unbolt the fuse panel from the cowl. The wiring was set up with enough slack so you can gently unfold it out away from the cowl and end up with it sitting with the fuses facing down in the vicinity of the air filter canister. You really don't need to access the fuses as much as the connectors on the back as many (but not) all of the wires behind the dash end up going through these connectors. The big exceptions are the grounds that are generally run individually to a threaded stud behind the dash. I think the gauge grounds share a common wire. Now remove the air inlet ducts between the engine and the big canister. A casualty of this is probably the foil/corrugated defroster ducts that are snaked in and around the air inlet ducts. I need to source a new supply and mine got crushed in the process. From there you can remove the hardware that holds the gauges in. There is also speedo cable and two air lines to be removed.
The warning light bar at the top of the dash is just pushed in with clips, I gently pried mine out but once the other gauges are removed you should be able to push the indicator out from the back.
You now have access to the harness through the gauge holes. The wires are bundled up for routing and protection from the wiper arm mechanism so you need to unbundle them. You next job is to locate all the gnawed wires and temporary mark them with white electrical tape or something that will make them obvious.
Its now time to get the electrical troubleshooting section from the volume 1 tech manual and start going through the individual trouble shooting sections, there are partial wiring diagrams and generally once you get the hang of it its not that difficult once you find the right wire numbers. The government did issue a wall poster of the electrical schematic but no one seems to have one. It was special order and not standard issue so I suspect there weren't a lot of them to begin with. Generally you want to figure out what wire number is at the indicator, switch or gauge connector and then locate the same wire where it goes in the fuse box or some other component. Once you find both ends you then can ring out the chewed off wires until you find the one with continuity. I use a Fluke DMM that beeps when I find continuity so it just a matter of clipping to known point at the connectors and then waiting for the beep as you go through the gnawed wires. Once you find that end, find the other end that runs from the indicator, switch or gauge. You would do the same thing with the grounds, just hook up to the ground stud behind the dash and ring out all the gnawed wires. I would use the ohmmeter and verify that all the suspected ground wires show low ohms as a light bulb may show continuity but will show higher ohms. I solder my splices and use heat shrink tubing. I would not use electrical tape for permanent repairs. I had 21 gnawed wires which means 42 gnawed ends, (plus several partially stripped wires that weren't severed but could cause a short). The going is slow initially but as the number of circuits get fixed, the number of gnawed wires are reduced. Eventually I ended up with few mystery wires and then I ended up doing a lot of homework in the manual for very little progress but eventually, I got them all except for one warning light.
The warning lights at the top of the dash are mostly a hot wire coming from the fuse box connectors running to a light bulb in the warning bar and then the other wire goes to the ground stud. I think the air cleaner differential pressure warning goes directly to a switch on the air cleaner. I did not look very hard for it and it is the only circuit that I didn't spend the time to get working.
Once you have everything hooked back up, you need to re-secure the wiring behind the dash. The wiper mechanism moves around behind the dash and you don't want the wiring to get snagged by the wiper assembly. I used mini ty wraps instead of tape.
I did find my notes (attached) which obviously were for my own use in diagnosis. They are fresh out of the book and could have errors and my penmanship is lousy. A definite Caveat Emptor applies.
The most important page is probably the 3rd page as that calls out the wire numbers I could find for the connectors at the back of the fuse box. Prior to unplugging the connectors label them permanently as some of the connectors appear interchangeable. Page 4 refers the block of four relays on the firewall above the air box. Do note that the illustrations in the manual showed the relays in different pattern that what is on my firewall.
View attachment Electrical notes.pdf
I expect if there was enough interest, a group of folks could catalog all the connectors, sketch them and identify the wire numbers for each pin. That would really help troubleshooting for everything except for the diagnositic test wiring which appears to have zero documentation. My opinion is that this harness is worthless to anyone without the dedicated electrical interface and isn't that "smart" so I wouldn't worry about it.
Good luck
