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Do all of these have an auxiliary Battery?
because I’m pretty sure I do, just can’t find it. Checked in rear where spare is located, under the main battery.
checked under seats, see no way there could be on there. The reason I think I have a aux battery is when I disconnected the main battery when reinstalled all radio stations were still programmed. Seems silly but if I do have one, I’d like to replace it. Thanks
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by Thguns
Do all of these have an auxiliary Battery?
because I’m pretty sure I do, just can’t find it. Checked in rear where spare is located, under the main battery.
checked under seats, see no way there could be on there.
Ours Aux is used for ECO Start / Stop, so is the larger one in the back with the spare.
Some models have the tiny Aux behind the dash, on the extreme left side ... basically above the Brake Release pull lever.
Many videos about this ... I'll try to find one ... tick tick ...
EDIT : okay, found a popular one :
https://youtube.com/watch?v=e5ZnvdjTdDM
Last edited by calder-cay; Jun 10, 2025 at 03:57 PM.
If you don't have START STOP feature you don't have an aux battery. If you did you have to lift one more panel just forward of the spare tire area you have pictured.
Concerning the GLK350, what I stated is correct. Your own video makes the distinction that only the Bluetec 250s have the small aux battery under the dash.
For gas models, only vehicles equipped with eco stop start have the larger auxiliary battery in the trunk to run the transmission pump.
Last edited by droptopchevy; Jun 14, 2025 at 07:54 AM.
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by Thguns
Do all of these have an auxiliary Battery?
because I’m pretty sure I do, just can’t find it. Checked in rear where spare is located ...
Our Aux is in the back with the spare. Here's a photo of our 2014 GLK350 Base rear trunk /spare area. I'm standing near the rear bumper for the photo ... I've marked where the Aux battery is - it's underneath that dedicated (Aux) cover on the right side. There's two bolts (where that can of fix-a-flat is) that need to be removed. There might be a couple more - I forget now.
I have one in my 2013 GLK 350 with ECO Stop, it needed to be replaced a couple of years ago. Mine is located under a plastic cover located behind and to the right of the spare tire (if you're looking in from the rear door at the bumper). I suggest you look under the plastic panels around the spare tire, as it seems like it moves around every model year. It may be that you do not have one if you don't have eco stop.
Also, you could bring your VIN to a dealer (or call one) and ask at the parts department if there is one of these batteries in your car and where it is. I'm sure they'd be happy to replace it for an incredible fee. If there is one, it's better to find one yourself at a much cheaper price at a battery store where you can get the proper replacement, not a general car parts store where they'll sell you something kinda sorta maybe close. Ensure to get one with a connection for a vent tube, as the safety blowouts occasionally fail. I have seen it, and the results. It is not a good thing to have the vented gases in your car, but is ultimately your choice.
Something that often gets lost or overlooked in the aux battery discussions is that the pre-facelift (2012 and older) GLKs don't have an aux battery at all. So the OP is chasing a unicorn... ;-)
Something that often gets lost or overlooked in the aux battery discussions is that the pre-facelift (2012 and older) GLKs don't have an aux battery at all. So the OP is chasing a unicorn... ;-)
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