83 GMC Instruments Do Not Work

[67RS/SSx2]

Okay, the Beast finally arrived. It is a 1983 GMC Sierra Classic 2500 crew cab. It has a 350 SB and a TH400 tranny. It runs rough at idle and low rpm but smoothes out when the rpm is increased. I'll work on that later.

First thing I noticed is that none of the dash instruments work. The volt meter - nothing. The engine temp gauge - nothing (although I expected this as the previous owner installed a below-dash aftermarket temp gauge that does work). Oil pressure gauge - nothing. Gas gauge reads about 1/8th tank on both tanks (it has the aux tank) even after I added 6 gallons to the RH tank and then 5 gallons to the LH tank. When I switch between tanks nothing changes...I am not sure it is truly switching.

I do not yet have a service manual for this truck. Is there a fuse that could affect all instruments except the speedo? Any suggestions on where I should begin my search?

I'm just getting started but it looks a little overwhelming. A lot to do!

Thanks!

[ray_mcavoy]

Originally Posted by 67RS/SSx2

I do not yet have a service manual for this truck. Is there a fuse that could affect all instruments except the speedo? Any suggestions on where I should begin my search?

Yes, there is a "GAUGES" fuse that powers all of the electric gauges in the cluster. I think some years labeled it as "GAU / IDLE" because it also powers an idle speed solenoid on some engines.

It should be located over on the left side of the fuse box, second slot down from the hazard flasher that's in the upper/left corner.

[67RS/SSx2]

Thanks! There was a white connector connected to the fuse block that hung over in front of the gau-idle fuse that made it nearly impossible to pull out. After a little work I was able to replace it.

Now the volt meter rises to ~13 volts when the engine is running. The oil pressure gauge bounces around 45 psi at idle and jumps beyond 60 psi when any throttle is given. Seems to read high. Think I'll try to pick up a new sending unit at O'Reilly's tomorrow to see if that helps.

Fuel gauge sets just below 3/4 now on both tanks. I'm still a little leery of that.