Hey guys, I am installing a tach and need some insight on which wires to use.
There is a black (ground), Green(tach signal), Red(switched Power), White (Light). I have a 1996 transam, so do I use the white pin#13 wire in the red pcm connector for the signal? What should I use for the switched power source? The instructions (not LT1 specific) say the white wire goes to the "panel lights". Which wire should I hook the white one up to?

Basically i need to know where I should hook the red, white, and green wire. Thanks guys.

 

I like using the radio fuse for sitched power

for the "panel lights" wire, do you have a fuse labeled instrument lights, or dash lights, ect.?

 

what do you mean by radio fuse? Where do I find that wire? Should I test voltage to be sure of which wires i am using? Should be 12v right? Or is it less?

 

TTT- Somebody has to know this! Any help would be great guys.

 

I am also installing a whiteface guage set and I am using a wire that goes "hot" when The lights are turned on to power those gauges. So... can I use that wire also as my switched power source for the tach?

 

Sorry for so many replys, But I need to get this straight here.

Red= Switched Power
Black= Ground
Green=Signal Wire
White= Powers lights

I found all wires except where the 12v+ switched power goes. Does anyone have a suggestion and maybe a picture of a wire I could use for this? Thanks

 

You want your tach to work any time the key is in the on position. There is a switched power tap in the fuse block at the end of the dash, labled "IGN". I have several switched accessories wired into that connection. You just crimp or solder a 1/4" female spade connector on the wire, and push it over the spade lug in the fuse block.

You want your tach light to be on whenever your lights are on. You can connect it to the switched side of the headlight switch, or you can pick power up off the output of the dash light dimmer rheostat if you want the tach light to dim with the dash lights. When I opened up the dash under the headlight switch on my Formula, I found an unused factory connector for the fog light switch (no fog lights on a Formula), and used that to connect the power for the lights I wanted to go on and off with the headlights.

Not sure about picking up the tach signal from the ignition.

 

its best(and easiest to hide) to get that from pin 13, connector A(Red) at the PCM, or if you can locate the tach wire at the back of the cluster, this is the RPM the PCM sees, so....., and it makes it easy if you are going to run a MSD or LTCC, ect.

 

Thanks guys, I used the wires all you guys mentioned and got it to work perfectly. Thanks alot