Guest Posted May 4, 2002 Share Posted May 4, 2002 i just installed a factory tach in my 72 GS. Hooked a wire from the neg of the coil and nothing. Does it need to be grounded, if theres something wrong with the tach how do i fix it? anyone have any suggestions? Link to comment Share on other sites More sharing options...
Guest Posted May 5, 2002 Share Posted May 5, 2002 Wiring diagram shows the tach to have a ground wire. It has been many years since the tach was installed in my GS, but I believe there were 3 wires. One for the coil, one for the ground, and one for power from the fuse block for illumination. Link to comment Share on other sites More sharing options...
Guest Posted May 5, 2002 Share Posted May 5, 2002 i tried a ground to the tach but still nothing. is my tach shot? Link to comment Share on other sites More sharing options...
Guest Posted May 8, 2002 Share Posted May 8, 2002 This is a long shot, but some tach's don't work if you have the Pertronix ignition upgrade. If you have the Pertronix it could be that. Link to comment Share on other sites More sharing options...
Guest Posted May 8, 2002 Share Posted May 8, 2002 nope its all stock. i think the tach is bad Link to comment Share on other sites More sharing options...
Guest Posted May 10, 2002 Share Posted May 10, 2002 the black wire from the tach needs to be attached to the frame of your car someplace where a good connection will be made, this is the ground. The red wire needs to be connected to your fuse block (perferably to a wire that is only on when the igntion is on.) The third wire, a green wire needs to be ran to the "tach" output on your coil, OR it needs to be ran to the negative out on the coil. Link to comment Share on other sites More sharing options...
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