Rather, how does it not work? I've had this problem for a while and it's mostly been intermittent, where the tach will start to climb and read anywhere from 1000 to 4000 rpms too high, even at idle. This would only happen sometimes, and then it would go away. The tach would go from reading correctly, then jump up and read too high, then jump back down. Eventually, it just pinned itself, and stayed there.
I finally had a chance to open up the dash and I found the tach wires, one of which has a splice with a connector in it. The connector wasn't exactly tight, but upon tightening it, my problem persisted. How would I be able to test for a proper voltage at the back of the gauge cluster? How is the RPM read by the tach? Is there a module that may be bunged up, or a bad ground, or do I have to just replace the instruments?
Anyone else experience similar problems?
Thanks.