Hey all,

I have a 2019 gla 45amg.

I drive it very little and had both batteries replaced at the last prepaid service a year ago
My kids were last to drive it, and since a week had passed thought to hook up the tender.
it was dead, but my schumacher sensed some life and I ran the 100amp boost til it cycled out and then put it on the 0-20 overnite
reading 12.5 today, and I pulled the charger, then dropped the hood, which set off the alarm.
It gives me a break with the damn horn after 30sec, but the hazards are flashing so I disconnected the brass nut negative and have peace.

I did not look at the dash, figured I would check here for some info first.

1 will it go away by itself overnite in a disconnected state?

2 if it starts alarming when reconnected, what are my options to reset it?
I have both original keys available

THANK YOU

 

So only when you close the hood?

 

When you hit the car with that 100amp boost, it probably caused a voltage spike that confused the alarm system, most newer MBs have sensitive anti-tamper triggers tied to sudden voltage changes. The alarm system on the GLA 45 is integrated into the CAN network and sometimes a dead battery or sudden charge like that will make the central gateway think the car was being broken into.

 

Possible cause thanks for chiming in.

 

without ability to clear faults.... you hands are tied
You dont have many options.

Try reconnecting without surging power while your tightening brass nut.

If still alarmed 50% chance: insert key fob in ignition slot. It's more direct that unstable KeylessGo module waking up.

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+++ NO killer 100Amp shot !!!
100A may have wasted the AUX caps module that hates high current like normal battery do.

A shot of 100Amp in a flat battery is hundred times the opposite of what to do.
Battery (AUX Caps) needs controlled charge current.

 

"jimyj" is a sales pitch. Have a look at any 5 or so of jimyj past posts. You just might notice the artificially personalized robotic responses that, about 80% of the time, happen to mention a certain scanner ;-)

 

behaved fine after a nite disconnected, hooked it up, no alarm
no current codes on the icarsoft

cleared out some more historic codes, car is quite unreliable actually, given 9K miles and 2 bad wheel speed sensors

Thanks for the thoughts

 

These great cars are service oriented. They need attention and frequent expert care.
The No1 best thing is to USE A BATTERY FLOAT CHARGER (CTEK or better) to disable many if the low-voltage issues that are built-in.

Disconnecting battery when unused is an excellent practice to disable standard "drain by-parking" and get a beneficial free Reboot.

The crazy alarm sounding is a side effect of soft-crashed CAN-B, the one responsible for battery drain.... Reboot gets temporary relief!

HOPEFULLY NO MORE JUMPS!