GLC 300 4Matic woes.

[AndyChapman]

Good afternoon all. I have just rejoined this forum after many largely trouble free years with an E220 Avant Garde. Now I have the above suv which is showing some eccentric and strange electrical faults.If anyone can shed some light on this it would make me a very happy man. First off, the (new) battery has a habit of discharging itself overnight. Come to the car in the morning it will not open on the key, new battery in there. Have to recharge the main battery which has dropped to some 3.5v. Had to get in with the metal key. Now only the driver's door will open, along with the tailgate. Nearside mirror won't close on the lock, or open. Mirror repeater on the winkers not working either. Even when the car's main battery has been charged it sometimes shows the 12vBattery warning message on the screen between the speedo and rev counter. Has anybody any clues as to why all this is happening? My local (very good) garage can't get any error codes. It's as if a real living gremlin has buried itself somewhere and enjoys causing trouble... Car is on a 2020 plate and has done some 43,000 miles. Not a lot to be having so many things going wrong! Kind regards, Andy

 

[Riva811]

When did you last replace the starter battery?
Otherwise it sounds like condensation or water damage

 

[AndyChapman]

Hi, that's an interesting thought... The battery was replaced in June, and more recently the garage put on a better quality battery to see if that made a difference. Still problems. I know of no water ingress which would cause this either. A complete mystery.

 

[Riva811]

Hi, that's an interesting thought... The battery was replaced in June, and more recently the garage put on a better quality battery to see if that made a difference. Still problems. I know of no water ingress which would cause this either. A complete mystery

Weird. I would get the mb oem one instead. You could have a parasitic drain somewhere, star diagnosis MIGHT be able to point at it