Has anyone ever experience any issues with their battery getting drained overnight? If so, what was the fix? I purchased an 07 CLK550 a couple weeks ago. I am reading over 13 volts at night, then 9 volts the next morning. I changed the battery. When the car is running, it ranges between 13 - 14 volts. The only problem I am aware of, is the drivers headrest stuck in the up position. I haven't had a chance to look into that problem, but have unplugged every connection to the drivers side seat tonight to monitor. If I continue with the issue, I was going to use my mulit-meter inline with the cable to see if I have any type of amp draw. Before I go through all the troubleshooting, I figured I would ask the forum experts for some guidance. Thanks for your time.

 

I haven't had the problem, but you might try locating and removing the fuse for the headrest.

 

Thanks... I'll give that a try. For now, It was quicker to disconnect the connections under the drivers front seat since I wasn't sure where the fuse box was located. I'm just getting to learn about the car. I'm hoping to get the WIS soon. I'll check again in the morning to see if the battery kept its charge.

 

Great start. The battery kept its charge with over 12v. Do you know where the drivers side headrest fuse is located?

 

Just happened to be doing some cleanup work on my car. There is a fuse layout sheet in the fuse compartment, just left of the light switch between the door and the dash.

In case yours has been discarded. "Seat adjustment, driver" fuses are 2, 21, 29. "2" is located in the trunk fuse box just forward of the driver side storage pocket. "21" and "29" are located in the fuse box referenced above.

But before you remove the fuses, search the forum for how to reset stuff. You may be able to just hold the switch for the headrest for "full up" and then "full down" for 5-10 seconds. If the headrest operates properly after that, you can wait another night to see if that addresses you battery drain problem.

 

I'll give that a try as soon as I get out of work. Thanks again. That really saved me a lot of time researching.

 

I narrowed everything down to the drivers seat. Knowing that the drivers side headrest was stuck in the highest position... I ended up pulling out the headrest motor. I found 3 of 4 connections to the motor circuit board with bad solder joints. I re-soldered and reinstalled the motor. My headrest is now working. Just have to figure out how to remove the dash message: Engage front-passenger seat. I'll find out tomorrow morning if the battery maintained it's charge. I'm optimistic. If it still drains out, at least I can eliminate the headrest out of the equation.

 

I've fixed both my headrest motors thanks to a post by xsever on this forum. seems like they are all bound to fail.

 

Now that I got the headrest fixed, I was really optimistic hoping that it was the culprit. Unfortunately it wasn't. I was puzzled because I thought the original drain was coming from the drivers seat, but it wasn't. The battery was still being drained overnight.

I had to start over from scratch by performing a parasitic draw test. I have 2 multimeters, both were only rated to measure up to 2 amps. Luckily my neighbor had a multimeter that measured up to 10amps. I started by pulling the negative lead and using the multimeter inline to measure for amps. I measured 6amps being pulled. After going fuse by fuse... Nothing. I was still puzzled. I switch the leads on the multimeter and it was reading 7amps. Looks like the multimeter was bad, so I switched now to another multimeter that my neighbor had his basement. This one also measured up to 10amps, only now it was reading 4 amps of draw regardless if the leads were switched. I went back and pulled each fuse. By now, I have been pulling so many fuses, that I started pulling 3 or 4 at a time. The draw was coming from fuses number 40,41, and 42. When removing all three fuses, my draw goes down to .5amps. When any of those 3 fuses are placed back, my draw goes back up to 4amps. There must be something that has all three fuses in common. I received the WIS and will have to find one of my older Windows laptop since my day to day laptop is MAC. The only thing I found to be odd, is that the alarm can still be heard with the positive lead disconnected. Perhaps there's a capacitor somewhere. Is this normal for MB? If anyone happens to know what device or ground might share all three fuses, please share.

Although I have only narrowed it down, below are a few lessons learned so far:

Use a multimeter rated up to 10 amps or more. Confirm the multimeter is good by switching leads. You should receive the same number, one as positive, the other as negative when you switch the leads.

Pull each fuse one at a time, if this fails, you may end up pulling multiple fuses as I did but will have to pay attention to detail to place each fuse in the correct location. Take a picture before you pull the fuses.

Be patient, because it takes about 10 - 15 seconds when you pull the fuse to see if the draw goes away.

 

Maybe this will help in your troubleshooting endeavor.....

 

Thank you for the pdf. There are 15 components that use fuses 40 - 42. It may be easier any related controller and disconnecting them while monitoring for the amp draw. Do you happen to know where the TeleAid or control module are located?

 

No, I do not.

You may be able to locate them from drawings on parts.com.

Rodney, or one of the other gurus, may know.

 

TeleAid is in the trunk, but fuses 40, 41 and 42 have nothing to do with that - 40 is right-side seat controller, 41 is for the ACC (climate control) module, and 42 is the instrument cluster.

I don't see the instrument cluster drawing 3+ amps. The seat controller could, and so could the ACC - a common ACC failure is a fan for the temp sensor int he overhead control panel. See if you hear that fan running after shutting down everything.

 

Thanks Rodney, I reconnected 41 and 42 and left out 40. I'll see how it holds up in the morning . I intended to take it to the dealer to see what comes up with their Star tool, however, the ABS light now remains on, and the shifter is locked. From reading online, I should be able to release the shifter by placing a screwdriver in a hole within the front cup holder, pushing down and forward. I attempted but can't figure out how to unlock it manually. Do you have any tips on releasing the lever.

 

Pop the wood (ore metal, if you have that trim) panel off of the center console and you'll see the lever on the back of the shifter module for the release.

 

Update: So soon after I was able to get the shifter released, I didn't have time to continue troubleshooting so I dropped off the car at a local MB dealership. They were pretty busy and provided a loaner until they were able to get to my car. It took them 8 days to get my car back, but I'm glad they only charged me the $130 they originally estimated for the diagnostic fee.

The MB mechanic stated that he identified a bad ESP module causing my shifter stay stuck in park. He stated that the battery drain was caused by me leaving my OBD2 bluetooth scanner plugged in and also recommended me to change the battery since it was now bad from constantly being drained.

I changed the battery (again) and measured the car when off looking for a drain, and didn't find one. When I plugged the OBD2 scanner back in, I was not able to reproduce the drain as indicated by the mechanic. At the end of the day, I can't reproduce the drain. A potential theory, is that the ESP module was the original culprit, which finally gave out. I have a used ESP module on order and hope to install it next week.

I'm happy that the drain appears to be gone, but would really like to know for certain what the true problem was. Hopefully the ESP module swap will go smooth.

 

For the sake of putting closure to this thread...


The drain problem has not continued. Due to the fact that I can't duplicate the problem, the most likely culprit is a defective battery. When I originally replaced the battery, I used a battery from my beamer that was totaled earlier this year. Perhaps that battery was already on it's last leg even-though I bought it about 6 months ago and never gave me problems before. Why the drain went away originally when pulling fuses 40 - 42, will remain a mystery. From reading through forums, a battery starting to go bad, can have weird issues that don't add up.


As to the ESP... I placed the original ESP back and took the car to an independent shop called German Auto Group in Northern Virginia. I asked them to attempt to re-program the ESP module, and left a spare one that I picked up from eBay for $70 in case it was truly bad as the MB tech indicated. I explained that I might have reset something in the process of removing fuses looking for the battery drain. They were able to reprogram the original module and I have been driving it since yesterday with no issues. My shifter will finally release from park, and the drain is gone. Now I can finally start working on the less stressful work like oil change and coilover install.


Rodney and Fatz.... Thank you for all your help.

 

Glad to hear it's working now!