New Caprice - Discussion forums

I currently do not have a second battery but will be installing one real soon. Before I do I want to make sure that the wiring is all correct.
There are a few cut wires and empty terminals in the second (pass side) battery mounting area that id like to address before hand.
Thanks for your help.
David

You will also need to make sure the AUX battery option is turned on in your BCM. An easy way to tell is to check and see if you got power on the yellow/green wire in spot 6 on plug X446. If no power check the fuse and relay but if they are OK then chances are it is turned off in the BCM.

Diagram: https://www.chiltonlibrary.com/content/ ... 601868.pdf
Pinout:

Basically all the vehicle wiring for the AUX battery comes through X446 and X447 (white and blue plugs above where the aux battery goes) then the main cable over to the main battery. All the rest of the wires you should get with whoever sells you thier AUX battery assembly. So this diagram shows everything that is in the AUX battery assembly wiring harness:

https://www.chiltonlibrary.com/content/ ... 903415.pdf

The car had the second battery was functioning at some point and there is a lot of wiring there already.
There is a heavy gauge wire coming from the main battery over to the aux battery area and connected to the isolating relay - most likely the changing wire.
The isolator relay is in place but with one empty big post - missing the big wire to the battery I guess.

Looks like a 10 gauge cut ground wire on the ground side of the AUX battery .
AUX side - Also on the positive battery terminal - a couple empty spots and disconnected circuit breakers.
And two harness that go to the console are unplugged above the aux batteries location.
My guess would be that AUX battery function is ON and they just unplugged, cut wires and removed the battery.
THANK YOU VERY MUCH FOR YOUR HELP.

smwalker wrote: ↑Tue Feb 23, 2021 9:59 pm You will also need to make sure the AUX battery option is turned on in your BCM. An easy way to tell is to check and see if you got power on the yellow/green wire in spot 6 on plug X446. If no power check the fuse and relay but if they are OK then chances are it is turned off in the BCM.

Diagram: https://www.chiltonlibrary.com/content/ ... 601868.pdf
Pinout:
X446.png
X446 wire.png



Basically all the vehicle wiring for the AUX battery comes through X446 and X447 (white and blue plugs above where the aux battery goes) then the main cable over to the main battery. All the rest of the wires you should get with whoever sells you thier AUX battery assembly. So this diagram shows everything that is in the AUX battery assembly wiring harness:

https://www.chiltonlibrary.com/content/ ... 903415.pdf