tach

Dave-R · Post by **Dave-R** » Sat May 01, 04 12:39 pm

I don't know what year car you have so this is general.

Normally you have three or four wires out the back of a tach. One is just for the bulb so ignor that. One maybe an earth or it may earth through the body of the tach.

There will be two other wires. One (power lead) gets connected to the battery + via the switched accessory circuit. The other (signal) goes to the -ve side of the coil.

If you just connect each side of the coil it will not be getting full voltage due to the ballast resistor.

If I remember right (slim chance) my 1970 tach only has two wires out the back. One will be dark blue because that is the live on most Mopars. The other will be green and goes to the -ve of the coil.

Dave-R · Post by **Dave-R** » Sun May 02, 04 8:19 am

The factory units are very inaccurate anyway Steve. Just an ornament really.