TC33d Tachometer and hour meter not working

[KrisHansen]

Good day gents, it's been a while since I've posted.. my 33 has been mostly trouble free since rebuilding it so many years ago due to a cracked block. I have a new problem that I'm dealing with, which is that the tach and hour meter have ceased to function. initially the hour meter would leap ahead when turning on the key, but that has stopped, and now just nothing.

the fuel and temp and idiot lights all work. I have confirmed voltage and pulses from the green wire that sends signal to the dash, but I don't know if the voltage (around 8 volts) or pulses (around 250hz at idle) are correct.

Anyone dealt with this issue before?

Thanks!

 

[jbrumberg]

Kris- If I remember correctly there the tach/hourmeter are driven by a cable I would check the connection of the cable driving the tach and hour meter. Good luck.

 

[KrisHansen]

It's definitely driven electrically, there is no traditional cable. I have the schematics, I just don't know if the readings I'm seeing are within spec.. Thanks!

 

[HAMMER TIME]

It's definitely driven electrically, there is no traditional cable. I have the schematics, I just don't know if the readings I'm seeing are within spec.. Thanks!

Kris,
I know that this post is a little old but I'm have the same issue with my tach on my TC33 and was wondering if you ever resolved this issue.
Thanks,
Jeff

 

[jigs_n_fixtures]

If it is a diesel the tach signal is typically generated at the alternator. So You’d need to know how the alternator is built, and the pulley ratio between the crank and the alternator to figure out how many pulses it should be giving out. But the signal is typically correct if you have one.

If gasoline, the signal comes from the negative on the coil. But at the frequency he was seeing, I‘d be inclined to say it comes from the alternator.

With two gauges not working, I’m inclined to think it is a power feed issue. I’d try to see if the power wiring to the tach and hour meter, are isolated from the rest of the instruments which are working. Look to see if the power to gauges is fed with a trace on a circuit board, as the circuit board can develop cracks, and the traces can corrode. Look for wires with chafing or rubs in the insulation, and wiggle the wires to see there is a connection which isn’t good.

 

[Halftrack]

See the attached thread for additional on TC33 tach.

TC35 Tachometer Failure

Dear Folks, TC35 tachometer not working, possible causes? Possible solutions? Thanks in advance! Kind Regards, Steve

www.tractorbynet.com

 

[HAMMER TIME]

See the attached thread for additional on TC33 tach.

TC35 Tachometer Failure

Dear Folks, TC35 tachometer not working, possible causes? Possible solutions? Thanks in advance! Kind Regards, Steve

www.tractorbynet.com

Thanks Halftrack. This gives me a place to start.

 

[dlctcg]

@HAMMER TIME - Besides the above mentioned thread, definitely check to make sure that wire on the back of the alternator is connected & the wire is not damaged (Oh, depending on the tractor & year that wire may not be green). If it seems to be connected correctly, you can check that wire for continuity as it runs from the back of the alternator to the instrument panel Connector (on the back of the instrument cluster), PIN# 20.
If you are looking at the connector plug (disconnected & facing you), it's on the bottom row & is the second pin in from the left.

Both the Hour Meter & the Tachometer are powered from the alternator so make sure you check all the connections on the back of the alternator.

From our NH repair manual:

Proof Meter (Hour Meter)- Records the hours and portions of hours that the tractor has been operated regardless of engine RPM. Use the proof meter as a guide to determine hourly service and maintenance intervals. The meter is activated by electrical current provided by the alternator.

Tachometer - Registers engine RPM (Revolutions Per Minute). The gauge is marked in increments of 100 and will return to zero when the engine is not running. The tachometer is driven electrically by the (P) lead of the alternator.