Practically everyone of the gauges in my 88 IROC-Z seem to be malfunctioning. I have taken the instrument cluster out, and about 5 of the bulb socket holders are missing from the cluster. The only gauge that seems to read right is the rpm gauge. I beleve the speedo cable is bad and thats why the speedo isn't reading nada. But, as for the rest I am not sure. I am willing to get any pics/videos or whatnot if it will help. I was wondering, would the missing bulbs stop a circuit from completing. And, in this case, could it mess with the gauge, meaning could it be the cause for the other gauge problems?

 

Bulbs are on a totally separate circuit, they won't affect the gauges.
Since your tachometer is working, I'd say that you have good power supply to the instrument cluster but the separate gauges have probably issues or their sending units.

What are you seeing on each gauge? Are they pegged? Are they moving erratically?

Lou

 

The oil pressure gauge looks to be half way, the gas gauge is pinned at full, and the speedo just stays at 0. With the cluster out and the car in gear, I watched the speedo cable and it doesnt move at all, which points me to a bad VSS as far as the speedo is concerned. It looks like 2 boxes are missing from my convenience center, which lead me to believe thats why like my belt light and such don't work.

 

The oil pressure senders do go bad and read low after a while. Either you can verify the reading with a mechanical gauge or just replace the oil pressure sender and see if it fixes the readout.

The gas gauge is either bad in the tank or the circuit has a broken wire somewhere.

The mechanical speedometer won't show any speed unless the cable is spinning, as you already know. The gears in the tailshaft might be stripped or not meshing right. That is more of a mechanical problem. Before you start replacing them, though, I'd disconnect the cable from the tranny tailshaft and try to spin it to see if it is moving freely or binding. Then I'd put a drill on it to verify that the speedometer actually moves.

Hope this helps.
Lou