Originally posted by Andy
When a CEL (or Check Engine Light) come on, it's because the ECM (Engine Control Module, your car's computer) got a weird message from one of it's sensors (or no reading at all). Basically the computer in your car thinks something is wrong and stores a code (which you can check) about what it's reading that isn't right. The issue with your gauge cluster sounds like to me is that you do have one of these CEL's. However, your old clusters had a burnt out light and never let you know. The new cluster has a working light and is trying to tell you. A CEL don't mean your engine exploded (often it doesn't come on when it does), just a weird sensor reading. What year Civic do you have? '96+ OBD II cars are very sensitive and will throw CEL's more often for emissions related problems than actual engine one's.
When you first turn the key on in the car, some of the dash lights come on, CEL, ABS (if equiped), SRS (your airbag system), and a few others. They all blink out quickly just to let you know they work. Put your old cluster in and see if come on when you first turn the key on. If so, my theory's shot to hell and it may be that your new cluster could be defective. If not, find a website that explains how to check the codes and find out what it's trying to tell you.
Also, the ECM stores the codes in it's memory. By disconnecting the battery for a few minutes, you wipe out the computers memory and it goes back to all it's factory defaults (think of restarting a windows computer, it's still works, but you lost what you were doing before the restart). That will eliminate the code and CEL but if the CEL is coming from some problem that still persists, say a sensors failed or not hooked up, it will come back. Seeya.
wow! thanks! i will try to check the codes and go from there. i'll let u know what happens or will ask more questions if need be!