# Adding a digital tachometer to a tractor



## JD3430 (Jan 1, 2012)

So one of the things I didn't notice about the used JCB I picked up is that the tachometer is jumpy and sometimes doesn't work at all.
How difficult would it be to add an aftermarket digital tach to it? 
I'd rather have the factory tach, but who knows where to get it fixed and how costly.
Anyone ever added one to a tractor?


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## 8350HiTech (Jul 26, 2013)

Is the factory tach all mechanical? It's quite possible the tach drive is bad or even a joint in a cable not quite meshing properly. Neither should be big money.

Hoober's should be able to help you with factory options.


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## somedevildawg (Jun 20, 2011)

I agree, fix the factory tach if at all possible.....


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## JD3430 (Jan 1, 2012)

Factory tach has wires to back of it, not mech cable. 
Works ok sometimes, sometimes it reads low, sometimes not at all. 
Wondering if it has a bad pick up.


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## mlappin (Jun 25, 2009)

Bad pick up or a bad connection somewhere, pray for the first.


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## Gearclash (Nov 25, 2010)

What year is that tractor? Lot of tachs in the 80s/90/s/early2000s get their signal from the alternator, and a flaky or inoperative tach/hourmeter is sometimes the first sign that the alternator is on the way out.


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## JD3430 (Jan 1, 2012)

Crap. Alternator seems fine. So pickup is on alternator? In the meantime, if it's 1000rpm mower, it would be nice to know what throttle setting to run. I'm just running by "feel" right now.


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## Gearclash (Nov 25, 2010)

Did you remove the alt and get it tested? I've seen the alt maintain battery charge but not have a tach signal. Testing proved the alt wasn't working 100%.


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## JD3430 (Jan 1, 2012)

Is the the tach signal a part on the alternator that can be replaced? I would probably just replace that as a start.
Tach works periodically but reads low when it works.


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## PaMike (Dec 7, 2013)

I would confirm that the signal on a JCB comes from the tach before pulling off the alternator...I would think a search of the net should yield you some quick answers to help you know where to poke around at.


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## 8350HiTech (Jul 26, 2013)

PaMike said:


> I would confirm that the signal on a JCB comes from the tach before pulling off the alternator...I would think a search of the net should yield you some quick answers to help you know where to poke around at.


Or a quick call to Hoober's.


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## JD3430 (Jan 1, 2012)

I'm pretty sure hoobers thinks it's a alternator pick up.


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## jd4230ps (Dec 9, 2010)

I've added a Tiny Tach to two 30 series deeres. They work good,easy to install. Sensor clamps around injector line, needs 12 v power and good ground. Features are, tach, maximum rpm recall, 4 timers= total engine hrs, job timer, 2 service time reminders set in hrs.


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## JD3430 (Jan 1, 2012)

jd4230ps said:


> I've added a Tiny Tach to two 30 series deeres. They work good,easy to install. Sensor clamps around injector line, needs 12 v power and good ground. Features are, tach, maximum rpm recall, 4 timers= total engine hrs, job timer, 2 service time reminders set in hrs.


Can you post up a link to the one you have? That sounds promising.

On edit: found it.
https://tinytach.com/diesel.php


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## JD3430 (Jan 1, 2012)

So I did a little looking around and found that the JCB alternator is only $78 bucks! Dealer wants $225. 
It seems too good to be true, but for a price like that, it seems easier to just replace the alternator.
Thoughts?
http://www.ebay.com/itm/ALTERNATOR-JCB-LOADER-185-65-with-6BTA-Cummins-0-120-484-018-0-120-484-026-/130657436630?hash=item1e6bca43d6:g:gUQAAOSwWnFWCUVE&vxp=mtr


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## Gearclash (Nov 25, 2010)

Could buy it and keep your old one as backup . . .


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## JD3430 (Jan 1, 2012)

Reviving an old and boring topic:
So I dug into the alternator replacement job. 
Disconnected batteries and began unplugging it. When I unplugged the small tach wire, I saw it was encased in some wire loom and that was encased in a larger bundle of wires. There inside the casings, I saw a small crimp on wire repair. On first look, it seemed ok. When I touched it, the wire to the tach fell out of the crimp repair. 
So I repaired it somewhat correctly with a heat shrink connector. Fired up tractor and the tach worked perfectly. 
Lesson: it's not always the exact part that you think failed causing the problem. Gotta look "upstream" and "downstream", too! 
Now the question is do I keep the alternator, or send it back. It's only $78. I'm thinking it'll cost $20 to ship it back. Maybe I'll put it on the shelf for another day. Lol


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## Wethay (Jul 17, 2015)

Keep it and you will never need it. Loose it or send it back and your's will go south.


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## Shetland Sheepdog (Mar 31, 2011)

Got the same problem with my Ford 5610-2! Also, have issues with fuel gauge and oil pressure light. Wondering if my issue just might be poor ground to instrument cluster.

Glad you found your issue JD.


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