im putting in an aftermarket tachometer, and i hooked it up to the white wire (ignition coil negative) and its not getting any kind of reading. i have all the wires hooked up, and the lights on the gauge are working, what could be my problem?

its an external coil. is there a different wire i could use?

OR, how can i fix the original tach? it gets some sort of signal and registers, but it doesn't start reading anything until the car reaches 2000 rpms. then after that it does move, but does not read accurately. its an 88, so is there a certain resistor i should check?

 

all i had to do to my aftermarket tach is hook it up to a hot with key, ground, the tach signal wire off the coil under the hood, and then the light wire .... if you want your stock one back you can find a cluster with a broken speedo or what not and just pull out your old tach and put the new one in.... here i a link to a post i did on how i set my tach up and black out the factory tach

https://www.thirdgen.org/forums/inte...indicator.html