lyonkster

All of a sudden I am getting the "battery" indicator light at startup after an all day or overnight rest, and the COMAND screen turns off soon after leaving the driveway.

The battery tests at 12.6V (supposedly 100% charge), and two shops did a load test confirming battery is good. Alternator puts out 14.7V at idle.

So I am wondering if the battery may be losing charge due to parasitic drains (never had this before though)?

Also, why would the COMAND screen be shutting down, could these be related?

Cwdawson

Doesn't the GLK have two batteries, one for starting and one for the rest of the equipment?

lyonkster

I don't think so (not 2011's at least). And from what I read, an auxiliary battery problem would be indicated by "auxiliary battery malfunction" message - I just get a battery icon on the dash.

bop11

Does the command screen come back after a short while by it self, or do you have to restart?

lyonkster

It does not come back on by itself, but does upon restart.

I should have mentioned also that the "SRS malfunction" warning came on just before the battery/screen problem started. I'm guessing that the SRS thing is a result of my disconnecting the seat harness to take out the driver seat to be able to remove the vent duct for the rear passenger, because (wait for it) a chapstick was rolling around inside the duct. What a stupid design, but I digress.

Not sure why disconnecting and reconnecting the yellow SRS connector would trigger the light (I did not have the key in during this repair), but I suspect it's related. No idea why "battery" and screen issue would start right after this, maybe a coincidence?

My plan is to take it in to my local dealer (the one that forgot to insert the axle after doing the motor mounts) and see what they say. I'll let you know what they tell me, I'm sure it'll be an interesting story.

lyonkster

Just to report back on this, it looks like it was the battery after all. Apparently when the battery voltage is low, COMAND screen is designed to shut off (no idea why that is). I put in a new H7-AGM battery, and all has been good so far.

MBKLUE

Could be a battery power saving strategy (turning off "non essentials" to leave the battery, hopefully, with enough juice for engine start/engine running). Also, many electronic circuits are designed to shut off if they're not provided with the minimum voltage to operate properly/reliably.