How to Hook up Tach - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rennat_2006 · 07-12-2009, 02:11 AM

Just wondering where the easiest spot is to get my tach rpm signal on my 77 k10 with a 400sb. I know some of these trucks were optioned with tachs from the factory and im wondering if it is as simple as finding the wire behind the cluster if it is even there or if im going to have to find the one off of the coil/distributor and what wire it may be.

Thanks

Prong · 07-12-2009, 02:41 AM

There's a tach terminal next to the ignition wire that plugs into the HEI cap. If you look on there, it's marked as such.

Walts_restoration · 07-12-2009, 03:06 AM

I like to use the correct tach plug, but i think some people get away with using a female spade connector. It will be on the distributor cap, right next to the BAT symbol (tach side should be to the front of the truck if i remember right).

Then all you need is a power source (key on IIRC) and a ground and a cluster light.

68 TT · 07-12-2009, 09:02 AM

I have used plain female spade connectors for the tach wire. It will work but they are difficult to install and when you squeeze the terminal edges tight enough to the back that they won't fall off the tach terminal they tend to fold over when trying to seat them fully.

Many junkyard GM cars have the same plug connector so it should be pretty easy to find the right one. I would bet you could get one in those Help sections at the auto parts store too.

*C-10 simplex* · 07-13-2009, 11:01 AM

jeg's and summit have the connector that goes into the hei cap for about $6 and that's what i've always used. Or if you're lucky ,as previously stated, you could find it at a salvage yard.

i can't get into deep detail right now because i'm really a beginner when it comes to electrical but i think i used an open spot on the fuse panel, i think it was labeled "acc" and plugged a spade connector into it. It only gets power when the ignition is turned on.

Definitely fuse this line This is soooo important. i used a 5amp fuse(mainly because i didn't have any smaller ones handy and the time). Maybe a 2amp would be better?

For Ground i used a bolt right near the parking brake pedal. Other things are grounded to it as well from the factory so i thought it would be the most appropriate place?

For lights/dimming i tapped into the marker light line using a "quick-tap" connector; i use a digital tach and the readout must dim at night as opposed to during the day.

07-12-2009, 02:11 AM	#1
rennat_2006 Registered User Join Date: Jun 2009 Location: Pasco, wa Posts: 111	How to Hook up Tach Just wondering where the easiest spot is to get my tach rpm signal on my 77 k10 with a 400sb. I know some of these trucks were optioned with tachs from the factory and im wondering if it is as simple as finding the wire behind the cluster if it is even there or if im going to have to find the one off of the coil/distributor and what wire it may be. Thanks

07-12-2009, 02:41 AM	#2
Prong Registered User Join Date: May 2007 Location: CO Posts: 475	Re: How to Hook up Tach There's a tach terminal next to the ignition wire that plugs into the HEI cap. If you look on there, it's marked as such.

07-12-2009, 03:06 AM	#3
Walts_restoration Real Projects never die Join Date: Jan 2007 Location: Lawrence, kansas Posts: 1,508	Re: How to Hook up Tach I like to use the correct tach plug, but i think some people get away with using a female spade connector. It will be on the distributor cap, right next to the BAT symbol (tach side should be to the front of the truck if i remember right). Then all you need is a power source (key on IIRC) and a ground and a cluster light. __________________ Ill put it this way, ive got a few lawn ornaments My name tag says Ryan KansasTwister On other forums

07-12-2009, 09:02 AM	#4
68 TT Still plays with trucks Join Date: Jul 2009 Location: Spokane, WA Posts: 3,556	Re: How to Hook up Tach I have used plain female spade connectors for the tach wire. It will work but they are difficult to install and when you squeeze the terminal edges tight enough to the back that they won't fall off the tach terminal they tend to fold over when trying to seat them fully. Many junkyard GM cars have the same plug connector so it should be pretty easy to find the right one. I would bet you could get one in those Help sections at the auto parts store too.

07-13-2009, 11:01 AM	#5
C-10 simplex Account Suspended Join Date: Dec 2008 Location: indisclosed Posts: 1,515	Re: How to Hook up Tach jeg's and summit have the connector that goes into the hei cap for about $6 and that's what i've always used. Or if you're lucky ,as previously stated, you could find it at a salvage yard. i can't get into deep detail right now because i'm really a beginner when it comes to electrical but i think i used an open spot on the fuse panel, i think it was labeled "acc" and plugged a spade connector into it. It only gets power when the ignition is turned on. Definitely fuse this line This is soooo important. i used a 5amp fuse(mainly because i didn't have any smaller ones handy and the time). Maybe a 2amp would be better? For Ground i used a bolt right near the parking brake pedal. Other things are grounded to it as well from the factory so i thought it would be the most appropriate place? For lights/dimming i tapped into the marker light line using a "quick-tap" connector; i use a digital tach and the readout must dim at night as opposed to during the day.



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