Hi first post here. Tried a general search but haven't found anything quite like my problem.

I just picked up a 95 GMC 3500 and had some issues on the 3.5 hour drive home. The truck ran fine but I noticed the Low Coolant light was on. Checked it and it was fine so I went on my way. Coolant light went away after a few km. About halfway home my CEL came on, for just a couple seconds but it cut off my cruise. Came on and went away a few more times but never actually affected the truck for the rest of the trip other than the cruise control. Also the gas gauge rapidly bounces within about a quarter tank of what it's actually sitting at.

I'm wondering if someone can give me a general idea of what could be the issue or where to look first. Thanks

 

Obs style trucks are known for a bouncing gas gauge. I have a 97 k1500 it does it. As for the coolant light possibly a coolant level sensor. And for the CEL try to get your hands on a nice diagnostics computer and see if you can look up a history of old codes and check the out. Its hard to get an actual code unless the light stays on. Just my 2 cents.

 

I know what you mean about the OBS. I've had a 98 Tahoe, 98 6.5 and a 95 Blazer. The gauges always move a little especially when starting and stopping. But even at idle this 3500s gas gauge bounces around like crazy. Don't know what could cause it other than an electrical issue. I'll know better when I rip into it. Thanks for the input

 

My 96 3500 does the same thing. Fuel gauge all over the place, oil psi up and down. Not a single gauge is reliable. Acts like a short some place.

 

Grounds are really important and overlooked in these trucks it's a good idea to pull all grounds and clean the especially the main ground on the rear of the passenger side cylinder head, and while you are at it do all battery connections this can be done for free another thing I have done is the battery bolt modification for my cables a total of less than $2, this is done by getting bolts that fit the battery connections use judgement when getting the lengths anything touching the positive terminal will melt and cause sparks.

Use bolts that fit the battery terminals from 1" to 1-1/4 get nuts that fit bolts
Run nut all the way to bolt head.

Bolt battery cables using the bolt (do not over tighten bolts into the battery terminal) run nuts down to tighten cables using back up on bolt head.