89GTdude

Alright well im putting a autometer tach in my friends car. I put a sunpro in the my car and it works great. Well anyways I have the white wire hooked up to the light switch and I go the backlight on the tach to work. I have the green wire connected to the negative side of the coil in the exact same spot I have mine. I have the red wire wired into a ignition wire that comes on with the car and I tested that and it pulls 14 volts when it only requires 12 and of coarse I got the black wire connected as a ground and even tried running it directly off the negative battery cable? Is there something im missing?

five0fm

is the stock one working still..i did that once and turns out it was a bad fuze.....if not recheck the connection to the neg side of the coil. i ran mine right off the existing tach wire...tan and yellow in my 92.

89GTdude

Ya the stock tach is working fine but does like to stick once in a while. I checked the connection and it was 14.08 volts from the wires off the coil?How can I find out what wire powers the stock tach?

five0fm

well i went online and got a wiring diagram...mines a 90-93...but it says its hte same colors as 87-89....when you take the stock cluster out there are two clips, the clip on your left is the one where the tach wire is...mine was tan with a yellow stripe. i got a florida 5.0 gauge cluster so i connected the autometer right to that wire and it works great.

89GTdude

I will have to try that. I have another old tach lying around I might just try that and see if its a bad tach. Correct me if im wrong but to test a tach dont all you have to do is have someone touch the redwire on the positive side of the starter cylinoid and the black to a ground then touch green tothe negative side of the coil?

projectresto83

Sounds like you have a bad tach or one of the wires that are attatched to the tach are broken at some point in its harness. I don't know about the testing a tach though.