A key to help identify alternator terminals

Posted by Peter Kennedy on 12/13/2018 to Alternators

This key might be helpful to identify the terminals on your alternators, as you can see the same function can have different designations depending on the make and model of alternator

Terminal	Definition	Notes
A	Battery	Battery positive connection
B	Battery	Battery positive connection
B+	Battery	Battery positive connection
C	Center	Centre point of a Y stator
COM	Conputer	Computer Connection
D+	Warning light	Comes from the old ‘Dynamo Positive’ on a generator
DFM	Dynamo Field Modulation	Duty Cycle signal from the ECU
E	Warning light	Comes from the word ‘Excitation’
F	Field	For externally regulated alternators
FR	Field Regulation	Voltage Signal from the ECU
G	Ground	Chassis negative connection
I	Inidcator	Warning Lamp
L	Lamp	Warning Lamp
M	Field	Found on older Externally Regulated units
N	Neutral	Centre point of a Y-connected stator
P	Pulse	Stator connection for tachometer
R	Relay	Output to charge relays, etc
S	Sense	Battery Voltage sense wire
S (FORD)	Stator	Stator Pulse. Used for tachometers
T	Tach	Stator Pulse. Used for tachometers
W	Waveform	Stator Pulse. Used for tachometers

12 Comments

js

Date 9/28/2020

Love it. thanks

Steven D Harris

Date 12/27/2020

Thanks - useful today for me! 12/27/2020.

Bob

Date 1/11/2021

I have a question I have terminal letter N on my alternator along with terminals B I and F. Those three I terminals are fine. The terminal N is my question? Can you help me?

Date 1/12/2021

Yoneda Jr Kloulubak

Date 9/5/2021

can I send you a picture of an 24v alternator and ask you to identify whether it's an internal or external regulated unit and also can you tell me where to connect each terminal ? This unit is most likely rebuilt and no connection instructions comes with it and vendor can't do much to help me. Thanks so much.

Johannes Åkrehamn

Date 9/15/2021

IG to ignition

Hammer

Date 1/17/2022

Good itechnical information

Jim K

Date 1/29/2022

Thank you so very much, straight and to the point, and I don't need to be a college professor to understand it. If only all things I need to look up were this simple.

Vasant Ichharamp

Date 2/28/2022

Very informative

Peter Sprunk

Date 8/12/2022

Hello Peter, greetings to you from Gympie in Australia! One of your Terminal Descriptions ... E = Warning light - Comes from the word ‘Excitation’ ... seems to be only half-right or maybe even incorrect. (See your website address below.) In an alternator wiring diagram I have, it certainly is not a warning light. The connection E appears to be the negative connection for the rotor coil in an alternator. Presumably that is then taken to be the exciter coil, hence the E. Or could E also stand for E = Earth? A friend (in Papua New Guinea) and myself (in Australia) came across this while trying to work out how to connect a Sterling Alternator Regulator; but we can't work out where exactly the two black wires go. Or better put, we worked that out, but we are not sure now whether the the E & N terminals on the alternator need to be connected to Earth, i.e. ground (B-). Various auto and marine electricians I have asked in my area don't seem to know anymore either. If you were interested, I could send you a photo of the diagram. https://shop.pkys.com/Alternator-Terminals-explained.html

Shane Chambers

Date 2/6/2023

F (Field ) = IG (Ignition) Would be nice to see a matrix of synonymous connectors. There seems to only be a handful, and yet everyone seems to want to 'roll their own' nomenclature. All these Engineers should have a pow-wow and and standardize the naming conventions. Should be something like BP/+ = Battery Positive. BN-/CG = Chassis Ground IG = Ignition

James Nicholas

Date 7/13/2023

Hello, I have noticed that in some applications R is used as signal tep for Tachometer is it so.

A key to identifying your alternator terminals