Hey all!

I have a 1990 Corvette and the digital part of the dash (speedometer, gas gauge, odometer, etc) doesn't work all the time.

It seems every time I do something with the battery (unhook it, or plug in a trickle charger when I'm at college for a few weeks at a time), the display shorts out. It won't display anything, then it will display partial numbers or just a random fixed display. After about 3 or 4 days of steady driving, it will start to work again. First it displays the speed, but takes about 10 to 20 seconds for the speed to actually come up, then stays there for 10 to 20 seconds until the # changes. Then it won't work on heavy acceleration or deacceleration. Then after those stages, it works fine, until I plug in the charger...

Any idea of what I can do, or what is causing this? I don't want to invest 600 bucks to swap out the entire instrument cluster, so I was hoping someone might have ran into this problem and had an easy solution.

So, can someone pleaseeeeee help me out here?

Thanks!

-Dave

 

If you don't have a Helms service manual, get one. You will see it called a FSM (factory/field serv. man.) on here. It will tell you exactly how to diagnose that problem. My initial guess would be a grounding issue though. Check the ground wires that connect to side of the block & bell housing on the drivers side. There are about 5 or 6 grounds that terminate in those two locations & one of them may have broke off...

 

I'll have to check that. I do have a Helms manual, just forgot where I placed it. Would make sense though, since I had trouble after replacing the motor on it.

 

The grounds on the top of the bellhousing on the drivers side all look good, but I loosened and cleaned them all anways. Still no luck.

Does anyone know where I can get the ground at a closer location, and maybe splice and ground it to somewhere else? That way I don't have to trace the wire from the instrument cluster to the original ground.

Secondly, can there be any other explination for this?

I seem to have lost my manuals, and am dead in the water right now.

 

After you check any grounds if there are any connectors that connect the wire harness to the back of the cluster, pull them a part(this may require a small screw driver to lift the clips clipping the male and female connections together and be careful to not be to forcefull or the clips will break. The get brittle in age and there is nothing you can doabout that. These connectors can get corresion on metal connection area you cannot even see some times, good stuff to use on the computer ECM plugs on the car at least onece while you ownethe car. If you do break the clipsuse some electrical tape and rap the connector tightly after reinstall. Get one wind with the tapeand the second wide pull tight stretch the tape and it hold it well, ifyou need to getit off in thefuture just cut lightly with a raiser blade and peal the tape off. Use some contact cleaner from auto zone the cheapest or radio shack and do all the plugs, spray well but try to keep it from dripping on the plastic by using a commone wash rag to hold the connecter why you spray it, the rag will obsorb the excess spray and not drip on your panel, where on occassion this stff might attach clear plastic surfaces like the partof the dash you look thru to the insturments,,,, good luck you will getit

 

You can download my scanned Electrical diagnosis service manual supplement 1990 from
www.ifsascandinavia.com/1990.rar
Its 140Mb. Hope it helps.

 

For Digi Info and Diags and Repairs you can do, go here:
http://www.batee.com/corvette/dcrg/index.shtml

 

IIRC, the '90 has a junction block with a bunch of wires just behind the battery. Not unusual for the nut that secures the wires to loosen over time causing all sorts of wierd issues.

FWIW, the digital portion of the IP gets its feed from the CCM.

 

Hi, your link no longer works.

 

Dave, did you ever resolve this issue and how???

 

Check over at Batee.com. Bryan has a wealth of info there and does both repairs and sells parts.

Good luck

 

Of course it doesn't work. Its 9 years old.

 

I had the same problem with my '90
It turned out to be a faulty ground in the hei coil

I almost tore the car apart, phoned Gordon Kilebrew and he said try that
Fixed the issue right away

 

Thanks!!!!! Did you have to replace the coil or just fix the ground? I appreciate the help!!