Battery Drain from Door Module
Thread Starter
Junior Member
Joined: Apr 2006
Posts: 34
Likes: 2
From: Mexico Beach FL
2007 S65 AMG, 1997 SL500
Battery Drain from Door Module
Hello. My 2007 S65 is experiencing a drained consumer battery after sitting parked in my garage for 3 or more days. I have replaced both the consumer battery and the starter battery as they were both several years old. The car has never failed to start but after sitting a few day i was noticing electrical problems like the trunk lid motor not operating, the message "command unit shutting down" on the command screen if I turned the car to "on" and did not start it withing 30 seconds or so. After charging the consumer battery either with a charger or driving the car these anomalies disappeared. When I monitor the voltage in the center display it is 13 to 14 volts when the engine is running. Also if I drive the car daily no electrical problems are apparent so I do not believe I have a problem with either battery or the charging system. I purchased an Amphound (a really helpful tester and time saver) and tested every fuse on the car (there are a ton) after shutting it off and letting it sit for a few hours. Only one fuse showed any current flow; fuse 80 on the passenger side dashboard end which powers the driver door module. My foxwell scanner also shows several codes that will not reset when I scan this module.
I suspect this module has failed. I plan to pull the door apart and then find a replacement module of the same part number. My question is would an exact replacement module be plug and play or would I need to have it activated by the dealer xentry system?
Thanks in advance. Without all the great info I've absorbed from this forum I would been in the poorhouse years ago from paying others to diagnose and fix my cars.
I suspect this module has failed. I plan to pull the door apart and then find a replacement module of the same part number. My question is would an exact replacement module be plug and play or would I need to have it activated by the dealer xentry system?
Thanks in advance. Without all the great info I've absorbed from this forum I would been in the poorhouse years ago from paying others to diagnose and fix my cars.
MBWorld Fanatic!
Joined: Aug 2014
Posts: 5,371
Likes: 1,693
S500
if your kit is any good it will be able to pull the software and module info
there were software updates on early car's to the door modules - but likely you had it as the usual issue is the windows wont work due to hitting a thermal cut out that doesn't auto reset.. the funny semicircular trim panel you see with the door open (normally hidden by the end of the dash) just pops off with your hand and you should see the door module and its wiring
there were software updates on early car's to the door modules - but likely you had it as the usual issue is the windows wont work due to hitting a thermal cut out that doesn't auto reset.. the funny semicircular trim panel you see with the door open (normally hidden by the end of the dash) just pops off with your hand and you should see the door module and its wiring
Thread Starter
Junior Member
Joined: Apr 2006
Posts: 34
Likes: 2
From: Mexico Beach FL
2007 S65 AMG, 1997 SL500
BOTUS Thanks for the input. Everything works properly on the drivers door. The drivers door module is not showing any codes except for stored codes associated with low voltage. They all can be cleared when the I run the engine or otherwise charge the batteries through the power distribution module near the starter battery. When I pull the 40A fuse that supplies power to the drivers door module the consumer battery does not run down if the car sits unused for a few days. Do you know if a replacement used module would be plug and play or would it require activation through a Xentry/DAS capable scanner?
Senior Member
Joined: May 2019
Posts: 305
Likes: 115
2007 S550
BOTUS Thanks for the input. Everything works properly on the drivers door. The drivers door module is not showing any codes except for stored codes associated with low voltage. They all can be cleared when the I run the engine or otherwise charge the batteries through the power distribution module near the starter battery. When I pull the 40A fuse that supplies power to the drivers door module the consumer battery does not run down if the car sits unused for a few days. Do you know if a replacement used module would be plug and play or would it require activation through a Xentry/DAS capable scanner?
MBWorld Fanatic!
Joined: Mar 2005
Posts: 1,033
Likes: 77
From: Wash. D.C.
'20 S63
Experiencing a similar problem with my '08 CL65. No error messages just a drained battery if left sitting for several days. Been doing a experiment by leaving the car unlocked while it's sitting over several days. Not one time has the battery drained while leaving the car unlocked. I suspect a faulty keyless go module in my case and will replace it soon as I don't drive the car during the winter.
MBWorld Fanatic!
Joined: Aug 2014
Posts: 5,371
Likes: 1,693
S500
used to be an issue with water ingress on door handles on old E class cars that flattened the battery
in general most Mercedes (and likely other cars) that use canbus fun, seem to get more voltage hungry with age... the idea with canbus is some weird beard networking and computers that do magic when they are behaving. If the car's voltage is lower than normal the logic around the network looses the plot and things forget to turn off - what causes what, in which order is the harder bit to find... are you aware at 2007 you might have a 35 amp hour battery up front and a monster 95 amp hour one hiding in the boot behind the rear seats ? if you have one in the boot, if no one ever touched it, it will be short of 200ml of water in each cell and almost not working...
if you get there to find its the original - I would recco a top up and recheck in 24hrs time then charge for 6 months - they are better made than replacement batteries and might (if given some TLC) in 8 months time, behave better than a brand new replacement
in general most Mercedes (and likely other cars) that use canbus fun, seem to get more voltage hungry with age... the idea with canbus is some weird beard networking and computers that do magic when they are behaving. If the car's voltage is lower than normal the logic around the network looses the plot and things forget to turn off - what causes what, in which order is the harder bit to find... are you aware at 2007 you might have a 35 amp hour battery up front and a monster 95 amp hour one hiding in the boot behind the rear seats ? if you have one in the boot, if no one ever touched it, it will be short of 200ml of water in each cell and almost not working...
if you get there to find its the original - I would recco a top up and recheck in 24hrs time then charge for 6 months - they are better made than replacement batteries and might (if given some TLC) in 8 months time, behave better than a brand new replacement
