Instrument gauge problem, can’t find much info

[melueloff]

My ‘88 Suburban V1500 is my father-in-law’s, I’ve been using it off and on for six or eight years, daily driver for last 2 1/2. Out of the blue one afternoon my water temp (stuck at 210,) oil pressure (stuck at 10,) volt meter (zeroed out) died and my fuel gauge started running backwards. It’s now stuck way above full. As it started getting dark, going down the road, turned on my lights, the headlight buzzer came on. Anytime the lights are on, key on and running or key off it’s screaming. I checked the fuse, blown, replaced it and it hasn’t blown since. I finally found the ground bus behind the left dash vent, three grounds, all tight and pretty clean. I’ve followed wiring (not my forte by any stretch of the imagination, even worse with wiring diagrams) and can’t find a problem. Occasionally the temp and oil gauges seem to move a little, but not like normal. I finally pulled the headlight buzzer for my sanity, but don’t know if that can cause other problems. He’s a fixer upper, long story, but starting to drive me crazy after a couple other problems. A buddy at work has an ‘87, but hasn’t been any help.

 

[melueloff]

Just to clarify, I have seen other posts about gauge problems, but it’s mostly been “check fuses, check grounds” in the replies. As I’ve done that to the best of my abilities, if someone has other suggestions, I’m all ears.

 

[gmbellew]

the only common thread between the instrument gauges being inop with ign on and the headlight buzzer going off with the ign on that I can think of is the ignition switch...

 

[75gmck25]

My best guess is you have a hot wire grounded somewhere, but instead of blowing a fuse it is providing a ground path for gauges and other devices.

My suggestions is to take a picture of the fuse block so you know exactly where each fuse is. Then pull all the fuses out, turn on the ignition, and see what works. I think that only the headlights should work, since they are usually on a self resetting breaker instead of a normal fuse.

Now start putting the fuses back in, one at a time, and turn the ignition on after each one is inserted. The point of this is to try to narrow down which circuit is creating the problems.

 

[melueloff]

Interesting thought. Hopefully tomorrow I’ll get a chance to do that. Another “newbie” question: what should the temp and oil pressure typically run?

 

[Jgonick]

I believe everything you mentioned is fed by pnk/blk-39. Double check the gage/idle fuse. (replace it just to be sure).
If that doesn't take care of the problem check for current on both sides of the the fuse.

What fuse did you find blown?


If it is a fuse blowing- next comes the fun part tracking down the short.

 

[melueloff]

It was the gage/idle that was blown. Replaced it, hasn’t blown yet but no change. Gonna try 75GMCK25’s suggestion. Hopefully tonight after work.

 

[78plowtruck]

Let us know what you find