I had to resolder the pc board on my 92 about 3 years ago. The board is easy to remove. The problem area on mine was at the board connector and one pin on a relay connection. A good light and a magnifier showed the pins in poor contact with the PC board at the solder joints.I read of the problem off the diesel page site and somewhere on this site, a common problem I guess.
92 chevy CK2500 354K miles. Underdash fuel gauge,teed into injector pump inlet with a needle valve air bleeder. Under dash ammeters on port and starboard glow plug circuits. Under dash oil pressure, and temperature guages. Rebuilt Tranny