New here I have a 2012 vintage Terex PT 30 that runs well but there is a problem with the charge indicator on the instrument panel. The red light is always on but the voltage at the battery is 14.0 to 14.4. The local ASV Terex distributor suggested that the diode on the fuse block may be the problem so I replaced it but it did not help. The tachometer also does not work but that has been an issue for a while but it wasn't a high priority. Any ideas?
An alternator problem most likely. The tachometer IIRC is connected there as well.
Agreed, sounds like an alternator that's not charging. Easy enough to test with a simple multimeter like this one: https://www.amazon.com/dp/B01C0IYLMM
The alternator is charging quite well. I mentioned in my original question that the alternator is putting out 14.4 volts.
have an ASV PT50 purchased new in 2009. Dealer had a quick connect on the battery; said to keep it disconnected when not running because it would discharge for sone unknown reason. He turned out to be correct. Alternator always put out the proper charge though. Replaced the alternator maybe five years later (battery light on). New alternator fixed everything; I leave the battery connected all the time and it doesn’t drain the battery anymore. So.....my vote is too put a new alternator in.
Did you confirm the amperage output?
Areas of an alternator can fail and it still have charge output. The light and tach signals usually come from the alternator.
You need a voltmeter in the cab to confirm that you have 14V+ when it's running and the lights come on. If you have that voltage, then don't worry about the amperage. Like Vetech said, the alternator drawing too much current to the excite will keep the light on even if the output voltage is fine. The tach comes off the wild three phase, or one wild phase of the alternator, so that's not likely to be the alternator problem, more likely the wiring or the tach itself.