Diesel Place banner
1 - 2 of 2 Posts

329 Posts
Discussion Starter · #1 ·
I am working on installing dual alternators on a 2005 LLY... The secondary alternator calls for an "charge on/off pin" in the ECM. Problem is, no one I've spoken with really knows the logic behind when/why the ECM drives that pin to command the secondary alternator to charge. If it's only when the electrical system pulls a certain amperage, I'd rather just let the secondary alternator charge whenever the primary is on... for the simple fact that two alternators working a light load together will prolong the life of both alternators... rather than loading up one all the time and rarely using the other.

Also, on the primary alternator, there are two pins... one I am assuming is the same as the single on the secondary... a "charge on/off pin". What is the second wire for?

And finally, the "battery not charging" message in the DIC... who knows why and how the ECM knows when to display that message? I've already figured it is not a drop in system voltage... because I've had that message on when one of my dual alternators was definitely charging...

Anyone who can shine a light on the mystery of the 2005+ LLY charging system gets a free cookie.

1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.