2005 NH TC29 DA TACHOMETER & HOUR METER STOPPED WORKING

[ranger13256]

Yesterday my tach and hour meter stopped working. Everything else works. Several days before that I had removed the starter solenoid hot wire to clean it as a possible reason for my click, click, click then start condition. I was careful not to disturb the wires on the generator. Anyone have an idea?

 

[kydick]

is it electric or mechanical?"

 

[ranger13256]

It is electrical. In addition, a new development has occurred. I put my trickle charger on the battery to make sure that is fully charged. After doing so, no more click, click and the tach works for maybe 20 seconds and then it stops. I think that I have eliminated the battery as it load tests fine but am confused as to why the tach starts working for a short time after a trickle charge.

 

[thclimer]

As you have also suspected, my first thought is a poor/intermittent electrical connection somewhere.

What type of load test did you do to the battery?

Are you indicating that now with a fully charged battery you can easily start your tractor, but now with the tractor running you still have the tachometer issue?

1) Have you eliminated mice chewing wires especially behind the gauge cluster?

2) Battery cables can corrode from the inside with the insulation looking good. You can use a set of jumper cables to "by-pass" them.

 

[ranger13256]

Load tester that has a heat element. The battery stayed right in the green. It also indicted about 14 volts while running that indicates to me that the alternator is putting out.

The tractor seems to start now every time with a fully charged battery and the tach will work for 10-20 seconds.

The wires behind the cluster appear OK and no mice

I will try the jumper cable idea to bypass. Good idea and thank you!

 

[thclimer]

The following attachments might be helpful:

 

[ranger13256]

Battery cables and grounds are good. The tach wire from the alternator to the instrument cluster has continuity. The alternator appears to charging the battery ( 13.5 volts) even though the battery always requires a trickle charge to bring it fully up according to my NOCO electronic charger. Yesterday, after charging, I started the engine and the tach worked for 15 minutes before dropping to zero. I am now thinking that the alternator may be have an issue regarding the signal to the tach even though it is charging. The belt is tight and not slipping. Thinking about purchasing a new alternator but hate being a parts changer and hoping for the best.

 

[Harry in Ky]

You can replace the alternator as a "maybe", but if it were me I would first check the output from "terminal P" and see what you get. Most electronic tachs on other New Holland tractors operate from AC voltage from the alternator. Very low voltage at that, like 8 or 9 volts. 5 volts is not enough. I know that from experience. This is on other models, not TC series tractors.

I would try to catch it when the tach works and see what the voltage reads. Then again when it's not working and see if there's much difference. The DC portion of the alternator can be working, keeping the battery up, charging at the proper rate and all that. In most cases repair shops only test that portion, and rarely look at the AC tap, so having it tested usually won't catch the problem.

 

[ranger13256]

Thanks for confirming what I was thinking. I will try to test that if and when the tach works. One other thought. Last year I replaced the start switch ( aftermarket from Amazon) after seeing the usual fried contacts, blown fuses and having the no-start condition. What are the chances that that the switch is acting up again? I see that it has some relationship to the tach, I believe. FYI, I replaced the 10 amp #2 fuse with a breaker. Possible that it is tripping and resetting?

 

[Harry in Ky]

I can't speak to that possibility other than to say I doubt it. As far as I know, the tach has nothing to do with any DC circuits, but I can't confirm that.