A little HELP please

[qtmileman2]

Hey guys & gals I have a 1989 T600 with a 855 cummins with a (i think) a factory shutdown system on it has a warning buzzer under the left hand dash above fuse/relay panel & warning lights overhead for low oil Pressure/high water temp(same Light), Low air PSI, Diff Lock, . A while back it started shutting down as it warmed up. Oil PSI & water temp OK and no warning light or buzzer. Screw in screw on fuel solenoid runs fine all day. I know I could just bypass this very easily but I like to fix things right since I put a driver in it from time to time.
I have looked and looked on the net and can't find a wiring diagram for this truck can anyone tell me where to find one local kenworth dealer was NO help.

 

[mndriver]

the only wiring diagrams are going to be with the manufacturer.

I know for my freightliner, you have to have your own account as a registered title holder of the vehicle. I am not sure how Paccar does there's.