i got a tach from sunpro for my 2000 3.8 camaro, and i just now got evrything hooked up. and my tach light and evrything works. but the RPMs doesnt. the sheet that came with the tach says i hook the green wire (which recieves the tach signal) to the white wire coming out of the powertrain control module pin id 8. i did that and its still not working!!? can anyone help me out?

 

There is a white wire (according to Haynes) that goes to the stock tach from the Ignition Control Module (ICM). There is alsoa white wirethat connects betweent the ICM and PCM (I think the one you tried). I would try hooking to the first one I told you, since you already tried the second.