# Tach and hour meter stopped



## tabaka45 (Mar 19, 2018)

Expanding this post beyond Ford/New Holland for a larger audience and reply. The tach and hour meter just stopped on my 1991 Ford/New Holland 455C backhoe. The schematic seems to show that they work off a connection to the alternator and a ground. Before stopping completely the tach would only work after revving the engine a little after starting and then seemed to be ok until shut down. I am hoping this is a simple loose wire issue, but before I go tearing in to things, does anyone have any suggestions? Thanks


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## Fedup (Feb 25, 2014)

From what I see the alternator on the 455C is also used on many other models as well, including the TB series ag tractors. I've been down this road and have learned that the AC tap on the alternator supplies the signal for the tach. Just a single wire circuit to the tach, not switched or connected to any other components I'm aware of. The alternator should put out 8 to 9 volts AC in order for the tach to operate. Those tractors I have found where the tach was not working had 5 volts or less at this post while running. They were charging fine, with no issues of battery draw, or anything else charging system related. They just wouldn't power the tach/hr meter.


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## tabaka45 (Mar 19, 2018)

Thanks for the information. I will check mine and see if that is the problem. That wouldn’t surprise me. After starting I always have to rev the engine a little to get the alternator light to turn off, but then it seems to work fine. I’ll put a meter on it this weekend. May be time for an alternator rebuild.


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## Hacke (Feb 22, 2011)

I do not know much about this, but the alternator has a temperature sensor at the battery.
Could the sensor be the culprit? Wiring?
https://avspare.com/catalog/newholland/54948/25195/677300/
https://www.messicks.com/part/82988248/sensor


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## Hacke (Feb 22, 2011)

I found that the 10-series has the same battery temperature sensor. I attached pages from the 10-series Shop Manual.
Read only the information under "2. Battery Temperature Sensor Circuit Test".

They did not bother to show resistance values for different temperatures, which is necessary when you are testing a temperature sensor...


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## tabaka45 (Mar 19, 2018)

Thanks. I'll look for the battery temp sensor in the service manual I have and try tracing it.


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## tabaka45 (Mar 19, 2018)

The alternator, Denso 54022336 E, is bad. Isn't putting out any volts at all. I have found a 
10565 Alternator 12v 55a IR/EF Lucas aftermarket for about $110 with free shipping. It looks exactly like the Denso. I have found some for less, but the plug configuration is a little different and that bothers me. Has anyone used the Lucas alternator, or have a suggestion for a replacement?


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## Hacke (Feb 22, 2011)

Or just replace the regulator?
https://www.walmart.com/ip/E8NN1031...and-Tractor-230A-2310-234-250C-260C/578309577


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## tabaka45 (Mar 19, 2018)

how would I know for sure that is the problem?


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## Hacke (Feb 22, 2011)

If the alternator is completely dead, it is most likely the regulator/brushes/slip ring that is causing the problem.
If in doubt, have the alternator checked at a specialist. If it is a genuine Denso, I would rather put new parts in it than replace it with a $100 alternator.

The rectifier/diodes can be a problem, but since nothing is happening I do not suspect it. Anyhow, you can get a rectifier for the same cost as the regulator.

10565 is not a Lucas number, I think you have found an alternator at:
https://www.fleetalternatorstarter.com/alternator_10565.aspx
10565 is that company's part number, the OEM numbers for this one are at the bottom. The alternator type is Lucas A127.

The previous parts list link was wrong, this is for 455C (I changed above):
https://avspare.com/catalog/newholland/54948/25195/677300/


And, never connect +12V directly to the "S" (Battery Temperature Sensor) terminal.


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## Hacke (Feb 22, 2011)

tabaka45 said:


> Thanks. I'll look for the battery temp sensor in the service manual I have and try tracing it.


Did you follow the steps in the service manual to test different parts of the alternator?


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## tabaka45 (Mar 19, 2018)

I just finished reading the test steps and I think that may be above my pay grade. I'll either take it to a shop or just buy a replacement. 

Also, would a bad generator and/or tach cause the hour gauge to stop or is that another problem? I'm not good at looking at electrical schematics, but it sort of looks like they are separate even though incorporated into the same gauge.


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## Hacke (Feb 22, 2011)

I found a Shop Manual, see the attached page.
***Edit
I have removed text containing wrong information. Corrections in a post further down.
***
You can check that the brushes are OK, without removing the alternator from the tractor. Disconnect the battery first.
Watch the first part, when he removes the regulator (you have to remove temperature sensor dongle as well):


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## marc_hanna (Apr 10, 2017)

I would just take it to a local starter and alternator shop. They can probably repair it for under $100 and usually in the time it takes you to go grab a coffee.


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## Hacke (Feb 22, 2011)

I looked at the detailed wiring diagram and I think I was wrong about the hourmeter. It does not have any connections other than power and ground, so it is most likely activated by vibrations. Is it digital?
If it is not working, check fuse #17 in the fuse box for power when key switch is in "Run" position ("Ignition" on).
The Yellow/White wire feeding fuse #17 (among others) comes from the key switch.


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## tabaka45 (Mar 19, 2018)

I just installed a new--not re-manufactured--alternator from Carquest and I still get the same results. Battery shows about 12.45 volts, running I only get 12.25 volts at the battery and at the alternator. All wires are correct and all fuses test good. My brother-in-law is coming over tomorrow and we are going see if he can find the cause. He is much better at reading the wiring charts, etc. By the way, I removed all the wires, except the battery and ground wires, one at a time and never got any increase in voltage. Wonder if my new alternator is bad.


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## Hacke (Feb 22, 2011)

Was the old alternator tested and found faulty?
Have you tried with a known good battery?
Is the battery temperature sensor tested?
Is the belt OK and not loose?
Is the alternator grounded properly? (Measure the voltage between the alternator housing and battery (+))
Is the charging light on, all the time, goes out when engine starts or never?


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## tabaka45 (Mar 19, 2018)

My brother-in-law came over today to help. We decided to check the battery temp first and found that the plug connection had come loose under the tractor. Plugged it back together and the tach now works and I am getting about 14 volts from the alternator. So, now I have a new alternator that I probably didn't need, but given the other one is about 30 years old I will just keep the old one as a spare. 
However, the hour gauge still isn't working. Looking at the wiring diagram it seems to share a lead with the tach but apparently doesn't depend on the tach to operate. All the fuses are good, so is there any way to test the hour gauge?


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