I bought a new battery at Walmart last year to replace one that died after 4 years, probably died because it had run down from an excessive current drain that I discovered to be due to salty corrosion inside the BCM.
This new battery doesn't seem to want to hold a full charge (reads 11,6 V on my DIC or 12.3V with a VOM after a few days) and I have been over the car a few times looking for another current draw, which I don't have. After my car goes to sleep. I read between 10 and 20 ma current draw. I have tested each fuse for voltage and no circuits at all are leaking anything.
I have been back to Walmart twice to get them to replace this battery, but they say it holds 12.4 V when they test and/or charge it and is within specs so they won't exchange it again.We all know 12.4 V is not nominal for a fully charged good battery.
So for the past few months I have kept it plugged into a 3 A smart charger continuously and only unplug it if I use the car. Never had a problem starting it even if the DIC says 11.5V, but I leave it plugged in anyway.
Today i unplugged the charger (read FULL when I did) started up the car, drove about 10 miles and got the Service Column Lock message on the DIC, and at that time my DIC was reading 14.5 V (as I leave it on to see what is happening).
I already have an LMC5 with the brown wire mod that I installed 5 years ago and have never had a problem with it or this message.pop up. The Reset button turned it off but it came back again later, twice, while riding 10 min after starting the car again, with 14.5V on the DIC.
Why am I getting this message? Could this be because of a bad battery with 11.5-6 V on starting the car, and why does it show up 10 min later when battery voltage is OK?
Very aggravating.

 

Moved to C5 Tech.

 

Anybody?
I may try and disconnect neg battery terminal for 15 min to reset computers and see what happens,

 

I don't see any issues with 12.4v on a resting battery. Have you properly check for a drain with a multimeter? Plug the black probe into the common (COM) jack input of the multimeter and the red probe into the amps (usually A) jack input. Then connect the red probe to the previously disconnected negative cable of the car loom, and the black cable onto the battery terminal.

Note: in order to test for current, the multimeter must be connected in series with the circuit as it needs to gauge electron flow, so to speak. Voltage, on the other hand, is measured in parallel.

You can also call compliance parts and and inquire about the LMC5 to see if it needs to be relpaced or there could be another issue with how the LMC5 was installed.

 

Robrote - I know you are trying to offer advice and help me, but have to take issue with many of your statements -

I am WELL AWARE of the procedure for finding a current drain, and I have none, and as I stated above I have a 10-20ma current draw after the car goes to sleep.

A fully charged battery at rest should read at least 12.6V. 12.4V is a 75% charge.
My battery is not optimal but I am using it for the time being anyway, constantly on a 3A smart charger when not driving the car.. If I disconnect it from the car and let it sit overnight, the voltage drops significantly from just sitting idle not connected to anything,

My LMC5 was installed over 5 years ago, there was/is nothing wrong in how it was installed, and I doubt the unit itself has failed.

I disconnected by battery for 10 min. allowing the computers to reset, and that seems to have cured the problem, the SCL message no longer appears. Undoubtedly, this message, like many other erroneous messages that pop up on the DIC, was due to low voltage. Hopefully the issue is resolved, I will let you know if it comes back.