Need Help with Tach!!

[Jekyl]

I bought a tach and I need to hook up a wire that clamps around a spark plug wire..Done.

But the other 3 wires I dont know what to do. The ground wire, a power wire and a light wire.

The gorund wire I tied around a peice of metal on the firewall on right of the pedals.

I need to splice into a wire that gets power only when the key is turned to the on position.... where can I find this wire? Be specific please. I tried splicing into 5 different wires under the dash and got no power.

Last but not least.. I have to splice the last wire into the dashboard light system so that when I turn on my dash lights... the light in my tach will turn on. The instructions dont say anything specific on how to do this...so how??

Thanks...

 

[cjman15]

What kind of tach is it? If it's Autometer, they have information on their website.

 

[seijirou]

Your ground is fine, for power there is a spare position on the fuse panel that gets power when you turn the key on, you can test for it straight from the front of the fuse panel, when you find it, stick a proper fuse in, and tap the other side of that fuse for power. You can buy fuse tappers at radioshack. For the light I'm attatching a diagram. The light blue with a red stripe is the wire you want, it's on the dimmer switch.

 

[HISSIN50]

how old is the tach? it has been forever since i have seen one that was not run off the neg side of the coil.

get yourself a test light - it will make life so much easier. as said, you can grab key-on power at the fusebox or any decent wire that is key-on hot. there are a couple big yellow (IIRC) ones under the column. people use radio triggers and whatnot also.

and you can get the dimmer at fuse 13. tap into the dead side of the fuse and stick a tiny (one amp if you can find it) fuse on the dimmer wire you run, so if you happen to get a short on that wire, it will hopefully not take out your dash lighting.

good luck.

 

[Jekyl]

its a brand new equis tach from walmart lol.. 3 1/2 inches diameter. having a hell of a time getting to and finding a power and lighting wire

 

[MrKwik]

I bought a tach and I need to hook up a wire that clamps around a spark plug wire..Done.

Around a spark plug wire?! I dont know about all that. There should be a green wire on the tach that goes to the negative side of the coil, not a spark plug wire. If you have an MSD box then there is a tach terminal on the side that you hook up to instead of the coil. Ground id easy, just find a screw that goes into metal. I have hooked up guages a few different places but if Im feeling lazy I just splice into the power and illumination wires behind the radio in one of those flat connectors. I think in that diagram above it looks like yel/blk for the hot in run wire wicch would go to the red wire on the tach and the lt-blu/blk would hook to the light wire on the tach which I believe would be white.