builte Posted August 12, 2023 Report Share Posted August 12, 2023 What is the p on the back of my alternator it goes on a 86 Nissan 720 Quote Link to comment
datzenmike Posted August 12, 2023 Report Share Posted August 12, 2023 Is it a terminal with wire on it? Quote Link to comment
builte Posted August 12, 2023 Author Report Share Posted August 12, 2023 It is not it's like the receiving end of connector with one flat metal prong with the letter p next to it that alternator and everything works fine I'm just genuinely curious because it seems to have no use Quote Link to comment
datzenmike Posted August 13, 2023 Report Share Posted August 13, 2023 Possibly some sort of noise suppression? Perhaps a capacitor plugs in here? 1 Quote Link to comment
thisismatt Posted August 13, 2023 Report Share Posted August 13, 2023 Pulse or phase. You don't need it for anything. 1 Quote Link to comment
builte Posted August 13, 2023 Author Report Share Posted August 13, 2023 Ok thank you both I appreciate it Quote Link to comment
mojojojo78 Posted February 23 Report Share Posted February 23 I was just going to post a question about this same terminal. I upgraded my alternator to one from a 280ZX. It also has the P terminal. Can this be used to run a tachometer that uses the signal from an ECU and not the standard aftermarket tachometers that use the distributor? Quote Link to comment
datzenmike Posted February 23 Report Share Posted February 23 The alternator is part of the charging system and it has no connection to the ECU other than to power it. Why would the ECU be sending a tachometer signal to the alternator????????? It's not a tractor. Quote Link to comment
mojojojo78 Posted February 23 Report Share Posted February 23 From what I could find is there are some alternators, usually used on diesel engines, that have a terminal that puts out a signal for a tach. It is obviously a different type of signal than what most aftermarket tachs use, mainly the negative side of the coil. There are some tachs that pull a signal from either the cars computer or this terminal on the back of an alternator. I was just wondering if this particular terminal labelled P puts out that type of signal that can run a tach. The reason I am asking is I bought a tach and GPS speedometer set. The speedometer works great. But I couldn't get the tach to run and that is because it wasn't designed to run off the coil. It was designed to run off either an alternator or from the ECU. Quote Link to comment
datzenmike Posted February 23 Report Share Posted February 23 Agree but too many variables like engine and alternator pulley sizes. The alternator would have to turn 1 to 1 or maybe 2 to one or some multiple of the engine RPM. Quote Link to comment
mojojojo78 Posted February 23 Report Share Posted February 23 Thanks Mike. I agree, there was a lot of calculating to do when using the alternator terminal as the signal for a tach. Quote Link to comment
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