Recently we traded a boat for a 1986 corvette, and the one thing that we've been having trouble with is the cluster. I'm aware of batee.com and I've diagnosed as many of the prone to failure components (photocell, power supply, 12 pin connector, light bulbs, etc) and they are all good according to the tests. I've also looked on several posts, and tried various things with no success. So what is happening is I have no backlighting whatsoever. If you look hard enough, you can faintly see the numbers and bars light up during the 2 second bulb test phase when you turn the key. They don't work whether the light switch is on or off (I have the dimmer switch turned all the way up, and the other dash lights light up), I even have turn signals and the bright indicator (both working properly). I've checked voltage throughout the circuit, from the fuse, to the photocell, all having proper voltage. Hopefully it's something simple that I've overlooked, but after a couple days of troubleshooting, I'm lost.

 

 

If the bulbs are good, I'd suspect the ground between the 2 boards in the cluster. Similar on the cluster working but not showing on mine but I also had the turn signal lights on solid at the time. The connectors between the 2 boards was burnt in mine. Batee fixed it and it's worked fine ever since.