Battery draining problems
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Junior Member
Joined: Nov 2012
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E coupe
Battery draining problems
Hi guys having issues with my battery dying. At first I thought it was a faulty battery so replaced with a new one but that died to. I've gone through the search engine but had no luck.
Symptoms I've noticed.
1- once the car is off the cigarette lighter still has power
2- the left side rear lights are dim when the car is running and was flickering and now has completely died
3- when the battery was dying and triggered off the alarm I could hear clicking coming from the fuse box area above the battery. Pulled relays/fuses but still clicking. Noticed another module behind the fuse box but the battery died completely before I could investigate if that's where the clicking was from.
Has anyone had similar issues? Is that black box behind the fuse box a Sam unit? Could it be a faulty Sam unit that's causing the cigarette lighter not to shut down when the car is off?
Anything to check to see what's causing the drain before I take it to a specialist.
Thanks in advance
Symptoms I've noticed.
1- once the car is off the cigarette lighter still has power
2- the left side rear lights are dim when the car is running and was flickering and now has completely died
3- when the battery was dying and triggered off the alarm I could hear clicking coming from the fuse box area above the battery. Pulled relays/fuses but still clicking. Noticed another module behind the fuse box but the battery died completely before I could investigate if that's where the clicking was from.
Has anyone had similar issues? Is that black box behind the fuse box a Sam unit? Could it be a faulty Sam unit that's causing the cigarette lighter not to shut down when the car is off?
Anything to check to see what's causing the drain before I take it to a specialist.
Thanks in advance
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C63 AMG
Good luck, I can't speak to your specifics. What I would do though is to disconnect, clean up and reconnect the chassis ground(s). It's a basic IMO that everyone seems to overlook when troubleshooting problems when there's systemic funkiness in the electrical system.
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2012 E550 Cabrio
I think my lighter goes off after dash finally fully powers down. Dont think I could keep charging my phone overnight for example. Now I have to try to find out tho!
Thread Starter
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E coupe
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From: Sidney, BC
2009 SLK55 AMG. & 2022 GLA250 4Matic
There is something else going on here other than there being power to the lighter whether is is 24/7 or not.
Remember that it only draws power when depressed. The simple answer if there is a question pull the lighter out completely and leave the socket empty.
My bet is nothing changes. There is a ground leak or something that is shorting insufficient to blow a fuse but is leaking off voltage.
Have you had a computer on it to try spot it with a code?
Remember that it only draws power when depressed. The simple answer if there is a question pull the lighter out completely and leave the socket empty.
My bet is nothing changes. There is a ground leak or something that is shorting insufficient to blow a fuse but is leaking off voltage.
Have you had a computer on it to try spot it with a code?
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2012 C63;1971 280SE 3.5(Sold);2023 EQS 450 SUV 4 Matic (Wife's)
Alex is correct about the lighter circuit. It is likely not the problem.
Anyway it looks like I am caught in a time warp as lighter circuits always used to be hot key off. But since I haven't smoked in 27 years and I don't own a cell phone that needs charging or a radar detector, etc I really have no idea of how a lighter is wired. I just tested mine and I bet it is the first time the lighter or the socket have been used since the car was purchased. Sorry for causing any confusion.
Anyway it looks like I am caught in a time warp as lighter circuits always used to be hot key off. But since I haven't smoked in 27 years and I don't own a cell phone that needs charging or a radar detector, etc I really have no idea of how a lighter is wired. I just tested mine and I bet it is the first time the lighter or the socket have been used since the car was purchased. Sorry for causing any confusion.
