on my 88 vette the cluster on one side(the tach side) is dark.but the speedo side is bright. whats going on? checked the bulbs and the fuses. could this be a ground issue?

 

If the lamps are good, then it is likely a poor connection between the lamp socket and the circuit board trace. You have to remove the cluster and take it apart to get to the traces.

 

Can anyone help me out here? I just bought a 1990 and the tack goes up to 10 when I start car. But then it wont work. Also I can't see any of my displays unless its dark out side. They are so dim even with the int light switch turned all the way up. Thanks

 

It's usually best to start your own thread, but I may be able to give some insight. I think your problem is possibly a bad ground connection. Not sure if the cluster uses a main power wire for everything, but typically they all share the same ground. In basic electrical, a series circuit, meaning multiple "loads" in one circuit, "circuit" meaning a full wired connection, total resistance is calculated by adding the load resistance values together. If I have one load being 3 ohms of resistance, and another load 2 ohms of resistance, in a series circuit, I would have 6 ohms of total resistance in the circuit. So you figure, ohms law, voltage / resistance = amperage, so 12.6 volts / 5 ohms = 2.52 total amps.

Essentially, if the light bulbs have a resistance value of 3, and the bad ground connection has a resistance value of 2, that is 5 ohms of resistance. That 2 ohms doesn't belong there. It should be 0.2 ohms at the most. So, amperage is mainly what will give you your brightness of the bulbs. So if you are getting 2.52 amps throughout the whole circuit, that would lower the brightness of you bulb, because if you do 12.6 volts / 3 ohms, you get 4.2 amps, which would be much brighter.

That was all an example. I tried to break it down for you to help you understand how a bad ground connection would cause something like this. That's where I would check first. Located the ground connection for the cluster, unplug the negative battery cable, measure the resistance value using an ohmmeter from the ground wire of the ground connection, to the actual metal surface that the connection is tethered to. It should be no more than 0.2 ohms. If it is more, you should clean up the connection with a wire brush or some sand paper. That will solve your problem.

 

Ok thank you I will try to find the ground problem. Sorry new to this site. I will open my own thread next time.

 

Your '90 is NOT similar to the earlier cluster that you tagged on to. I'd suggest some "searches" for 1990 tach issues (there will be many). Lot's to read. You can try the same for what I believe you meant to mention is an LCD issue and maybe not "all the displays" which was interpreted by Daniel as to being a problem. There is though I believe maybe 14 - 16 bulb/socket for the cluster back-lite. 6 - 8 more for warning lights. You mentioned "unless it's dark" so I interpreted that as an LCD issue in the cluster center. Maybe I'm wrong.

The search function works very well on this forum. Use the one that's "for this forum" at the top right in both the "general" and "tech" OR use the "C4 Community 84-96" and it should do all of the C4 threads.

Example: http://forums.corvetteforum.com/sear...rchid=39400676