installing factory tach

[Adamds86]

Hello everybody. I bought a new cluster that has a tach for my 1973 GMC K25. One problem though, my truck didn't originally come with a tach sooo I need to know how to wire the tach into the truck...on the back of the tach there is a 3 pin connector labeled coil, ground and 12v...could someone help me out with wiring this?

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[bucket]

Did you get the correct year range of cluster? You need one with an ammeter, and not a voltmeter. The tach is labeled just how it gets wired. The ground goes to ground, 12+ goes to ignition power (your gauges fuse would be a good hookup) and the TACH wire goes to the negative side of the coil. Unless the truck has been converted to HEI, then it just hooks to the TACH terminal on the distributor cap.

 

[RetroC10Sport]

Yeah, if you try to plug a voltmeter cluster in a truck with an ammeter, you're gonna have a BAD time.

 

[Adamds86]

it is a cluster from a 74. I figured out the wiring. my hei distributer had a section right on it for a tachometer that I spliced into. Thank you very much.

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here's a picture of the finished job.

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[RetroC10Sport]

Looks good!

 

[animal]

Nice find

 

[74 Shortbed]

Looks great..

 

[75 short]

doing same to a 75 what is the slot at the bottom of speedo for thanks

 

[Adamds86]

doing same to a 75 what is the slot at the bottom of speedo for thanks

it is a park brake indicator when park brake is actuated it lights up.

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[75 short]

thanks appricate

 

[Camatruder]

I did the same in my '91. Love having a tacho.

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