Can someone tell me what each of these do. The plug to the steering column and also short out the MAXI fuse The one that is totally burnt used to be blue. Yes I was lucky the truck didn't burn.

 

Don't have a 1990 FSM so Going to guess that it's the wiring to the headlight switch.

 

Sorry but no. It goes to the ignition switch. I've figured out that the blue wire runs the fuel shut off switch but I'm not sure what else. The only way I know this is because I fired the truck up and cut it and truck shut down. If someone knows more please let me know. Thanks tcows for your support nput

 

Here Ya go Dan.....did a little google searching a found this....

https://www.dieselbombers.com/1st-ge...-diagrams.html

Hope it has what you need.

 

As I remember, the blue wire provides 12v to these and maybe others.
Fuel shut off valve
Intake heater solenoids
OD solenoid

As you can see it runs behind linkages and past hot things. The only fuse to it is the fusible link. Shorts in that circuit are common.