charosenz

Here is a pic of the small wire terminal on my alternator. I am not using and OEM ECU.

I have heard conflicting reports. Some say this "small" wire goes to the idiot light. Other say this needs to go to power to "turn on" the alternator. Can someone give me some ability to know which answer is correct?

I will also include a pic of the alternator plate details.

It is a 2015 Civic, 1.8L,

tech8

The 2015 Civic has a LIN (Local Interconnect Network) controlled charging system. The alternator voltage regulator has a LIN wire going to the PCM (the LIN wire is yellow). The LIN wire allows the PCM to control voltage and load response control rate. The PCM can also read back information and status of the regulator and alternator through the LIN wire. The LIN provides control/diagnostic on the same wire.

There most likely is an IC chip in the regulator since there is the LIN wire.

charosenz

Thank you for the reply.

What I am learning is that ECU sends a 5 volt reference signal that has varies the duty cycle to control the alternator output. Since I am not using and OEM ECU, I am hoping to learn the range of duty cycle the LIN circuit can handle. I suspect, but do not know, that it varies between 50% to 99% duty cycle.

If anyone knows the typical duty cycle range of either the ECU output I would appreciate knowing this. A graph that shows the coorelation between the output and the duty cycle would be super appreciated.....

charosenz

I have learned that the duty cycle varies from virtually zero to 99 percent.

I am hoping someone can advise what the frequency of this 5 volt reference signal is that the ECU sends to the LIN terminal on the alternator.

I would be grateful if someone who has an oscilloscope would be willing to take a reading off the small wire on their alternator which of course would reveal not only the frequency but what the pulse width is.

I am unable to do this myself as I have this engine on a test stand and I am not using an OEM ECU.

I hope someone can help.

Thank you.