vdo tach ?'s

[NICKG]

ok, i have this gnx dash(new, never installed) avc made it. my question is about the tach. whan i hook it up(i tried 2 cars) it reads only when the car is cranking, as soon as it fires, the tach drops to 0. also, when you turn the key to on, the tach moves from rest to 0(as it should) so i bought the caspers converter for vdo tachs, put it in and same thing(in both cars) i checked the wireing (with the converter installed ) and no signal(on a dvom)
is the converter bad? i shipped it back to caspers along with the tach to be tested. i tried another tach (from a old porsche) and nothing. this is very frustraing as the wiring may be wrong on the tach, it has terminals marked 2 3 4, but all the directions list 2 + -. are these the same? what about the 3 dip switchs on it? the setting on it from avc is different than the one shown by caspers?
i searched the archives and saw no symptoms like this. HELP!!!!!!

 

[Matt Weiser]

You probably have a bad converter from Casper's. Apparently they shipped out a whole bunch of bad ones, but they've been real good about fixing them. This happened to me. Same symptoms as you, shipped back the converter with the tach, and when it came back from Casper's everything worked fine. I'm assuming you don't have your tach/converter back from Casper's yet?

You ought to set the dip switches on the tach according to Casper's directions and follow all the other directions they give -- including unhooking the stock digital tach connector behind the dash.