Under-hood negative terminal disconnect on a 2013 G-550?
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From: Lake Oswego, Oregon
'13 G550, '77 FJ40, '18 F350, '87 Westy, '87 Wolfsburg, '17 GLE350, '08 GL550
Under-hood negative terminal disconnect on a 2013 G-550?
Is there a way to disconnect the negative terminal on a W463 m273 engine without opening battery compartment inside cabin? IOW, when I want to work on the engine, can I disconnect the negative side of the battery from the engine compartment? TIA!
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W212 MY'14 M276-3.5NA @75kMi
Show us pic of engine bay passenger side, brass post.
Also consider "AUX batt" must be disconnected before Main so it does not lock up ISM... if so equipped.
Last edited by CaliBenzDriver; May 23, 2026 at 08:16 AM.
Thread Starter
Junior Member
Joined: Oct 2023
Posts: 16
Likes: 0
From: Lake Oswego, Oregon
'13 G550, '77 FJ40, '18 F350, '87 Westy, '87 Wolfsburg, '17 GLE350, '08 GL550
will take a pic and post today. Re the "Aux battery must be disconnected first before main"...there is no way to do that in my G-550. The main battery sits in a box and must be pulled out before I can access the aux battery. Are you sure that your statement applies to all Mercedes with aux batteries or the vehicle you're most familiar with. Thanks!
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
will take a pic and post today. Re the "Aux battery must be disconnected first before main"...there is no way to do that in my G-550. The main battery sits in a box and must be pulled out before I can access the aux battery.
Are you sure that your statement applies to all Mercedes with aux batteries or the vehicle you're most familiar with. Thanks!
Are you sure that your statement applies to all Mercedes with aux batteries or the vehicle you're most familiar with. Thanks!
AUX supplies the chassis backup power as soon as Main batt goes out.
Hopefully disconnecting main batt. won't drain your AUX batt.
Some AUX use capacitor module instead of actual battery...
Last edited by CaliBenzDriver; May 23, 2026 at 10:48 AM.
Thread Starter
Junior Member
Joined: Oct 2023
Posts: 16
Likes: 0
From: Lake Oswego, Oregon
'13 G550, '77 FJ40, '18 F350, '87 Westy, '87 Wolfsburg, '17 GLE350, '08 GL550
So does that mean, we should be disconnecting and pulling out the main battery completely and then disconnecting the negative terminal of the aux battery before doing electrical/mechanical work on the car? What a hassle. I swear, MB likes to make life difficult!
Last edited by Ridefly; May 23, 2026 at 11:02 AM.
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
battery NEG disconnection
You simply need to disconnect the NEG(-) side connection (GND) of a battery for it to be out of circuit.
Removing the main battery out is seriously heavy... is it in the way to prevent access to AUX connections ??
beautiful van in Mainland CN.
Last edited by CaliBenzDriver; May 23, 2026 at 08:54 PM.
