87' 944 S gauge cluster not working...
 

okay so i bought a 87' 944 S last monday nov. 24th. The person that owned the car before me installed a silly auto zone tachometer. He said the gauge cluster "was" working before the tach was installed, but I dont know if I believe it. Anyways, where should I start?
The tach was wired to the fuse box, i've already ripped the tach out and unwired it all. however, I havent figured out how the oem gauge cluster works (ie. whats connected to it). Is there maybe a sensor or something that might be left out? thanks in advance...

-James

I think there's (2) "X" relays you can replace and the quages will work.