These instructions apply to the Mercedes GLC Mk1 (X253) 2015-2022.
For other models, please choose your vehicle here.
The Mercedes-Benz GLC (X253, 2015–2022) has a main 12 V battery plus a small auxiliary battery. This guide covers the main 12 V battery — the one you disconnect — and where to find it. You might take it off to fit a new battery, to isolate the car before electrical work, to stop a parasitic drain over a long lay-up, or while recovering from a flat. Done in the right order the GLC relearns cleanly; the main jobs afterwards are the clock, the windows and, on a brand-new battery, registering it to the power-management system.
Where the Batteries Are
The main 12 V battery is in the engine bay, under a cover — this is the one you disconnect. Lift the cover to expose the two posts: the negative (−) earth normally has a black cap or clamp, and the positive (+) a red cap. Identify both before you loosen anything.
- A small auxiliary ECO start/stop battery lives in the rear (boot/under the rear-seat area, driver’s side) — it’s a separate, low-current battery you don’t normally touch.
- On the plug-in hybrid GLC, keep clear of the orange high-voltage components; the 12 V main battery is still owner-safe, but the orange HV cabling and connectors are not.
Before You Start
- Switch the ignition fully off and make sure the car isn’t in READY on the plug-in hybrid; check the dash is dark.
- Take the keyless remote out of range so the car can’t wake and re-arm mid-job.
- Turn off the lights, climate and accessories, and close the doors.
- Note any aftermarket audio security code; the factory head unit reloads by itself.
- Give the modules a minute or two to sleep, then work with gloves and eye protection and the right spanner.
Disconnecting the Main Battery
- Switch everything off, take the keyless remote out of range, and wait a minute for the electronics to settle.
- Slacken the clamp and disconnect the negative (−) earth first, then tuck the lead clear so it can’t flick back onto the post.
- If you are removing the battery, disconnect the positive (+) next, then undo the hold-down clamp and lift the battery out level.
Reconnecting & After
- Refit the battery and clamp, then reconnect positive (+) first and the negative (−) last. Tighten both firmly — a loose earth causes intermittent faults.
- Reset the clock; the displays reload on their own.
- Re-initialise the windows and, if fitted, the sunroof — see our GLC window guide. Until then, one-touch and anti-pinch may not work.
- A new battery should be registered to the power-management system with a diagnostic tool so the charging strategy matches it. A same-battery disconnect/reconnect doesn’t need this.
- Any warning lights that appeared usually self-clear after a short drive as the systems re-baseline.
If a Warning Light Stays On or the Car Feels Off
- Check both clamps are tight — a slack terminal is the usual cause of post-reconnection gremlins.
- Drive gently for a few minutes so the systems relearn; many messages clear themselves.
- Re-run the window (and sunroof) re-initialise if auto functions still play up.
- If you fitted a new battery and start/stop or a charging message lingers, it likely needs registering with a tool.
- Rule out a genuinely flat or old battery, and read any stored code before changing parts.
Frequently Asked Questions
Where is the battery on a Mercedes GLC X253?
The main 12 V battery is in the engine bay under a cover — that’s the one you disconnect. A small auxiliary ECO start/stop battery sits in the rear and isn’t part of a normal disconnection.
Which terminal comes off first?
The negative (−) earth comes off first and goes back on last; positive (+) connects first on the way back. It removes the earth path so a tool touching bodywork can’t short the battery.
Does a new GLC battery need coding?
Yes — a new main battery should be registered to the power-management system with a tool so charging suits it. A quick disconnect/reconnect of the same battery doesn’t need registering.
Do I need to touch the auxiliary battery?
No — for normal disconnection you only deal with the main 12 V battery under the bonnet. The small rear auxiliary battery is left alone.
Will disconnecting clear fault codes or the service light?
It may drop some temporary codes, but a real fault sets the light straight back. It does not reset the service reminder — use our GLC service reset below for that.
Can I jump-start it instead?
Yes — if you only need to get going, use the marked jump points rather than disconnecting anything. Disconnection is for renewal, storage or electrical work.
For any warning light that stays on, look up the code on autodtcs.com. To clear the service reminder, see our GLC service reset.
Independent guide — not affiliated with Mercedes. Always follow your official service manual and safety precautions. Read our full disclaimer.