John CC

I know, normal, right? The problem is, it doesn't come back on the next time you start the car. This behavior just started a few days ago. It's as if they pushed a software update over the weekend...

A simple push of the button puts it back on, to the previous settings.

Or is there a setting somewhere that inadvertently got changed?

jpj

I have a 17 GLS450 just started doing the same thing. Doesn't always turn off but just sometimes when I restart it is off and I have to turn on after restart.

John CC

Are they secretly pushing software "updates" through the air?

jpj

I doubt it, I would assume you have to update it manually. Mine is very random.

John CC

Mine switched from "never" to "every time".

jpj

Possibly your auxillary battery? Located in the back right corner compartment next to the spare tire. About $50 at a battery store, you don't have to get the MB brand. If you disconnect the 2 small wires on the battery tabs on aux battery, then take a test light to it after it's been disconnected for a while and see if it's holding a charge. Pretty sure I have an head unit issue, occassionally won't play any audio till I restart then will work. So much fun figuring this stuff out!!

John CC

I thought about that. Wouldn't I get a warning message?

jpj

You would think so!

Conchasjim

I also suggest checking the auxiliary battery. But not only for voltage, but load test it as well.
These vehicles do all sorts of random things when either battery is defective.

John CC

Just an update: It started working again yesterday. Instills great confidence...

John CC

Update:
It's on again - off again.

Conchasjim

I would take the auxiliary battery out and have it load tested. If you can't find someone to test it, just replace it.
These vehicles do whacky things when the batteries are marginal.

John CC

Just FYI, no aux battery warnings and no issue starting the car, even after it has sat for a week.

BlownV8

One sure fire way to tell if the aux battery is starting to die is that the engine will not turn off when in eco mode.

John CC

It has never done that in cold weather, and it's winter right now. Guess I'll have to wait until spring.

BlownV8

I'll bet you a $ it's your aux battery.

John CC

If I replace it and it doesn't change anything, I'll be expecting a lot more than one dollar!

BlownV8

When was the last time you replaced your aux battery? You should have no expectation of a reimbursement as the advice is free much like I don't expect anything if it does work. These cars do funny things with failing batteries.

John CC

I'm not talking about reimbursement for advice solicited, just asking for better odds on a friendly bet. You're asking me to risk at least $60 to win one dollar. Only a fool would take that bet.

John CC

Interesting. According to the EPC my X166 has the same tiny aux battery as my X204, not the larger one like an ATV or motorcycle might have.

WIS seems to say otherwise, but also refers to hybrid drive, which I definitely don't have.

BlownV8

Power Sonic 12V 12AH 200CCA Start/Stop Automotive Auxiliary Battery - SLIPSAUX14 at Batteries Plus

John CC

I can put the battery from one of my bikes in and test the theory.