What makes the hour counter work on a 4720H and fuel Gauge

[Slowpoke Slim]

I don't know the answer to your question, but you might try looking at the hour meter itself. I would think it uses 12v dc power (I could be wrong, but it would seem strange for it to run of un-rectified power). If so, supplying it power from any switched 12 source would work. As with other instrumentation components, the hour meter ground could be your problem as easily as the supply side, so check your ground. Improper intuition seems to always cause people to concentrate on the power supply side and to overlook and assume that the ground is good. My experience leads me to believe grounding problems are just as, if not more, frequent.

Honestly, I have no idea what the tach needs for a signal or power. Does it generate it's own internal timing pulse off of getting plain old DC power, or is it using the unfiltered output of the alternator as a "timing pulse" to trigger the "clock" in the tach? It may actually need both 12v DC and the timing pulse from the tach? It might be easier to get it to read true engine rpms if it's getting non-filtered (non-rectified) signal directly from the alternator?

 

[Cougsfan]

The tach works by counting the pulses from the alternator, converting it to rpm. If you lose your alternator you lose your tach. (I know from experience) It sure seems that the hour meter is nothing more than a clock that is turned on when either the ignition is on or the engine is running, one of the two, and has no need for the AC current. I know my tractor seems to tick off an hour in one hour regardless of engine rpm. It would seemingly add needless complexity for the hour meter to depend on unrectified power. But again, I am not sure.

 

[ptsg]

The tach works by counting the pulses from the alternator, converting it to rpm. If you lose your alternator you lose your tach. (I know from experience) It sure seems that the hour meter is nothing more than a clock that is turned on when either the ignition is on or the engine is running, one of the two, and has no need for the AC current. I know my tractor seems to tick off an hour in one hour regardless of engine rpm. It would seemingly add needless complexity for the hour meter to depend on unrectified power. But again, I am not sure.

That's pretty much it. The Hour meter just gets the signal from the alternator to know when the engine is running so it starts counting, otherwise it would count hours every time the ignition as on, even without the engine running.

 

[ericm979]

That's pretty much it. The Hour meter just gets the signal from the alternator to know when the engine is running so it starts counting, otherwise it would count hours every time the ignition as on, even without the engine running.

My old Kubota did that. The meter would click over when the ignition was on and I was warming the glow plugs before starting it.

 

[bigrich954rr]

OK thank you ill have to dig around