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sprinkles08, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 22817
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I own a 2002 CL500 and have been having battery problems. My

Customer Question

I own a 2002 CL500 and have been having battery problems. My battery runs completely down after two days unless it's driven. My problem began when the trunk motor failed and as a result the trunk didn't seal properly in a rain storm. I had the Benz dealer replace the trunk motor, which allowed my trunk lid to seat and seal properly however the battery continually runs down as mentioned. Today I replaced the battery with a new one and when I did I inspected the newly installed trunk motor. It sits underneath the battery, with a cap over the cavity between battery and trunk motor and is housed in a sponge like holder (the part number on the sponge like holder is A21580000135). The sponge cradle for thhr trunk motor was completely soaked from the rain that entered due to the trunk problem. I removed the motor, pulled out the sponge like cradle and noticed that both the positive and negative terminal on the trunk motor were in constant contact with the wet cradle. I assume that this is effectively causing a ground condition, so after I did my best to dry out the cradle I placed a piece of thick plastic between the two terminal and the sponge like cradle, then put the cap over the trunk motor and then installed the battery. Do you think the wet sponge like cradle making contact with the two terminal on the trunk motor would cause a ground that drains the battery? Do you think I should do something else in addition to what I've done?
JA: Is this your first time dealing with this issue?
Customer: no the dealer has been trying to figure it out for weeks, I have become frustrated with their service, they should have noticed the sponge like cradle was sopping wet when they replaced the trunk motor. This car, although a 2002, has only 31k miles. I am the original owner.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I guess these messages are computer generated because I've already answered that same question in detail
JA: Anything else you think the mechanic should know?
Customer: I've said it all
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mercedes Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Mercedes
Expert:  Chad Farhat replied 1 year ago.

Hi my name is ***** ***** I will be assisting you today

Customer: replied 1 year ago.
Hi Chad....what do we do form here?
Customer: replied 1 year ago.
Customer: replied 1 year ago.
Last time...Chad..are you out there?
Expert:  Chad Farhat replied 1 year ago.


Customer: replied 1 year ago.
I'll keep an eye on my email.
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

The water you found may or may not be related to the battery continuing to die at this point but you'll definitely want to make sure everything is dried. You can leave the connector unplugged and see if the battery still dies, or you could do an ignition off draw test.

What needs to be done to actually diagnose the issue is an off draw test. An ammeter needs to be set up between a disconnected battery cable and it's post. After about ten minutes if the draw exceeds 30-40mA then there is cause for concern. At that point then either fuses can be removed to see what the draw drops, or voltage drop across fuses can be checked to see what circuit current is flowing on. Once the offending circuit is found then components on it can be concentrated on.