Trouble Installing Tachometer - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Black70c10 · 01-10-2014, 06:30 PM

I can't believe I'm creating a thread for something so simple but I'm getting frustrated and figured I'd see what you all thought. Appreciate the input

Bought a sunpro tach and I've got the power running to an accessory fuse, the black on a ground under the dash (also tried directly to neg terminal), the white isn't hooked up yet, and I have the green hooked to the top of the negative coil. It's the most bizarre thing, when I start it up the dial definitely moves, but it moves right to zero and does not fluctuate at all. I thought maybe it wa ts the ground so I tried about 15 spots with the same result.
I even tried hooking the green up to the positive side of the coil and it shoots up to 3,000 RPM but does not fluctuate with throttle..
Seems like power is not an issue as its a 12V source, I can't imagine the ground is an issue..has something to do with the green wire but I can't figure out what in the world I'm doing wrong..

Any advice?

Longhorn 70 · 01-10-2014, 06:53 PM

I have a dumb question. The negative side of the coil is going to the distributor, right?

kelbystanley · 01-10-2014, 06:58 PM

Quote:

Originally Posted by Black70c10

I can't believe I'm creating a thread for something so simple but I'm getting frustrated and figured I'd see what you all thought. Appreciate the input

Bought a sunpro tach and I've got the power running to an accessory fuse, the black on a ground under the dash (also tried directly to neg terminal), the white isn't hooked up yet, and I have the green hooked to the top of the negative coil. It's the most bizarre thing, when I start it up the dial definitely moves, but it moves right to zero and does not fluctuate at all. I thought maybe it wa ts the ground so I tried about 15 spots with the same result.
I even tried hooking the green up to the positive side of the coil and it shoots up to 3,000 RPM but does not fluctuate with throttle..
Seems like power is not an issue as its a 12V source, I can't imagine the ground is an issue..has something to do with the green wire but I can't figure out what in the world I'm doing wrong..

Any advice?

If you have it wired this way and it still doesn't work, you have a bad tach. Return and exchange. I've had this happen before.

Black70c10 · 01-10-2014, 07:23 PM

Thanks. I wonder about that side note on the top of that picture you sent. Says something about having to use an adaptor with MSD ignitions... Could this be?

kelbystanley · 01-10-2014, 07:39 PM

I'm running the msd andd do not have the adapter. no troubles.

kelbystanley · 01-10-2014, 07:42 PM

Post a few pics of your ignition set up so we can look at it. I assume you have an external coil. If you have an MSD with the coil built in to the cap, Hook the green wire from the tach to the white wire on the dist.

**TBONE1964** · 01-10-2014, 07:57 PM

Are you running a MSD 6AL box or just a stand alone 12V ignition coil. The SunPro tachs are wired the same as any conventional tachometers. The green wire will go to the negative side of the ign coil or to the tach output on the MSD 6AL box. If you have it wired this way and it does not work, then your tach is bad(as kelbystanley stated). I do not suggest touching the green wire to positive )12V) in the future as this can also cause damage to your tach. It sounds as simple as a bad tach right out of the box.

**bigmac73** · 01-10-2014, 08:11 PM

you said you had the power hooked up to an accessory fuse, it has to be hooked up to a ignition source fuse not an accessory

kelbystanley · 01-10-2014, 08:15 PM

Make sure you have 12v on the red wire when the key is on. The green wire to negative post on coil, and the yellow or white wire (depending on tach) to a switched 12v forr the light. If it doesn't work that way you have a bad tach.

Black70c10 · 01-19-2014, 09:38 PM

Thanks for the help guys... I was doing something stupid. I had the tach feed wire going to the negative coil terminal like I usually do. However, with the msd ignition, that wire is supposed to feed into the tach terminal on the ignition box... Got it working. Thanks

kcsa75 · 01-19-2014, 11:58 PM

Quote:

Originally Posted by Black70c10

Thanks for the help guys... I was doing something stupid. I had the tach feed wire going to the negative coil terminal like I usually do. However, with the msd ignition, that wire is supposed to feed into the tach terminal on the ignition box... Got it working. Thanks

I love it when a plan comes together.

01-10-2014, 06:30 PM	#1
Black70c10 Registered User Join Date: Sep 2013 Location: Houston, TX Posts: 44	Trouble Installing Tachometer I can't believe I'm creating a thread for something so simple but I'm getting frustrated and figured I'd see what you all thought. Appreciate the input Bought a sunpro tach and I've got the power running to an accessory fuse, the black on a ground under the dash (also tried directly to neg terminal), the white isn't hooked up yet, and I have the green hooked to the top of the negative coil. It's the most bizarre thing, when I start it up the dial definitely moves, but it moves right to zero and does not fluctuate at all. I thought maybe it wa ts the ground so I tried about 15 spots with the same result. I even tried hooking the green up to the positive side of the coil and it shoots up to 3,000 RPM but does not fluctuate with throttle.. Seems like power is not an issue as its a 12V source, I can't imagine the ground is an issue..has something to do with the green wire but I can't figure out what in the world I'm doing wrong.. Any advice?

01-10-2014, 06:53 PM	#2
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: Trouble Installing Tachometer I have a dumb question. The negative side of the coil is going to the distributor, right? __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

01-10-2014, 07:23 PM	#4
Black70c10 Registered User Join Date: Sep 2013 Location: Houston, TX Posts: 44	Re: Trouble Installing Tachometer Thanks. I wonder about that side note on the top of that picture you sent. Says something about having to use an adaptor with MSD ignitions... Could this be?

01-10-2014, 07:39 PM	#5
kelbystanley Registered User Join Date: Sep 2012 Location: Lafayette, LA Posts: 39	Re: Trouble Installing Tachometer I'm running the msd andd do not have the adapter. no troubles.

01-10-2014, 07:42 PM	#6
kelbystanley Registered User Join Date: Sep 2012 Location: Lafayette, LA Posts: 39	Re: Trouble Installing Tachometer Post a few pics of your ignition set up so we can look at it. I assume you have an external coil. If you have an MSD with the coil built in to the cap, Hook the green wire from the tach to the white wire on the dist.

01-10-2014, 07:57 PM	#7
TBONE1964 Cluster King Join Date: Nov 2012 Location: Junction City, OR Posts: 5,263	Re: Trouble Installing Tachometer Are you running a MSD 6AL box or just a stand alone 12V ignition coil. The SunPro tachs are wired the same as any conventional tachometers. The green wire will go to the negative side of the ign coil or to the tach output on the MSD 6AL box. If you have it wired this way and it does not work, then your tach is bad(as kelbystanley stated). I do not suggest touching the green wire to positive )12V) in the future as this can also cause damage to your tach. It sounds as simple as a bad tach right out of the box. __________________ Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C

01-10-2014, 08:11 PM	#8
bigmac73 Senior Member Join Date: Mar 2012 Location: Chesapeake, Va Posts: 1,275	Re: Trouble Installing Tachometer you said you had the power hooked up to an accessory fuse, it has to be hooked up to a ignition source fuse not an accessory __________________ Mike 72 C-10 Cheyenne off frame resto and Upgraded to 4 wheel disk, Tilt, Dakota Digital Dash / Rear slider. 421 SBC / TH350 3000RPM Stall Progression Ignition /Holley 750 DP/3:73 gear Eaton Limited Slip unit / 2 1/2 exhaust glasspacks

01-10-2014, 08:15 PM	#9
kelbystanley Registered User Join Date: Sep 2012 Location: Lafayette, LA Posts: 39	Re: Trouble Installing Tachometer Make sure you have 12v on the red wire when the key is on. The green wire to negative post on coil, and the yellow or white wire (depending on tach) to a switched 12v forr the light. If it doesn't work that way you have a bad tach.

01-19-2014, 09:38 PM	#10
Black70c10 Registered User Join Date: Sep 2013 Location: Houston, TX Posts: 44	Re: Trouble Installing Tachometer Thanks for the help guys... I was doing something stupid. I had the tach feed wire going to the negative coil terminal like I usually do. However, with the msd ignition, that wire is supposed to feed into the tach terminal on the ignition box... Got it working. Thanks



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