So my donor engine for the Case 430 swap has a 24v alternator which isn't going to work for me, however I found a Bosch universal type one but it only has the B+ and D+ terminals (simplicity at its best!), no P terminal for the tachometer. According to the wiring diagram the thin red wire goes to the P terminal which goes.to the tachometer input on the cluster, question is: what does it do as there is no tachometer as far as I can see? Will everything work without it connected?
That is misleading, wire 124 does say input to tach, but I think it is the voltage sensor. There is no light for the alt charging. If the alt or battery voltage gets to low or to high, the hours goes off the panel and low or high voltage appears instead.
Yes and no. According to Mr Google, the P terminal (as indicated on the wiring diagram) is indeed the "pulse" output used for tachometer in diesels. When I was trying to get the wiring sorted I powered up the unit with an old battery, and no engine, alternator wires were not connected anywhere and low voltage error came up on hour meter display. Put a better battery in the next day and no error message, so that wire was not giving the info to the cluster. Further research suggests that tachometer signals are sometimes used to indicate the engine is running and thus used to start the hour meter. Not sure if it is used the same here? The alternator I have sometimes has the W terminal which is also used for the tachometer albeit a different signal, apparently it is a "wave", so probably a tap directly on the stator before the rectifier. Mine does not have this terminal populated but that can be fixed with a soldering iron. I just don't want to damage the cluster by giving it the wrong signal.