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Roger, BMW Master Tech
Category: BMW
Satisfied Customers: 5895
Experience:  10 yrs. experience as BMW Master Technician, shop foreman and dealer.
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525i: I am having high battery drain issues(2007 BMW 525i),

Customer Question

I am having high battery drain issues(2007 BMW 525i), dealer says that the diagnosis pointed to Comfort access on all doors, so all the door handles need to be replaced. they say that the door handles has special paint on them and when the car got repainted, the CAS is not sleeping and it continously draws current thru the doors, which causes battery drain. i dont understand that part. only front door CA works and rear doors dont open with CA. is there a solution other than replacing the door handles? thank you
Submitted: 2 years ago.
Category: BMW
Expert:  Roger replied 2 years ago.
Hello, I have seen a lot of door handles cause a parasitic drain on BMW's. The door handles come painted due to exact paint has to be applied for them to not have issues. The diagnosis is plausible for this to be a bad door handles. The only work around would be to unplug the door handles so comfort access is disabled. This should stop waking up the CAS and the vehicle should no longer drain the battery. This is often a test I do just to make sure that this is from the door handles. If your BMW does not have rear door comfort access they don't need to be replaced. Only the front would need to be replaced. I would only get these from the dealer due to the pain process. It should take care of the problem.I hope this helps. Please provide positive feedback as this is the only way I receive credit for helping. Thank you!Best Regards,Roger
Customer: replied 2 years ago.
Thanks for the reply. rear door CA has bee unplugged, but the dealer says it did not help to stop the problem. looks like they need to remove the door to unplug which is costing more rather than fixing the issue. Dealership says that unplugging will not solve the problem (i dont understand why). are you sure about it?
Expert:  Roger replied 2 years ago.
Let me explain what I think they are missing. To replace the door handle that is bad it has a plug going to the door handle that has the sensor. This will disable the door handle. I think they are disconnecting the door connector at the door A pillar which would then cut power to the door and also the door handle. This is done during diagnosis to tell which door handle is bad. But I think if they leave the door handle itself unplugged then you lose comfort access for the door and other doors potentially but you can still lock and unlock with the key normally to open and close. If the CAS is what is waking up it and they say it is from the door handle keeping it awake then unplugging the door handle only should eliminate the problem if they are correct. I hope this helps. Please remember to select a positive rating once satisfied with my help. Thank you.Best Regards,Roger
Customer: replied 2 years ago.
Thank you. is it true that the door handle color matters? as per the dealer, when the door closes current thru the door handle will be shut. but due to the paint mismatch (exterior body of car got repainted) car is not shutting the power and continuously draws current which causes drain. they want me to replace all four handles and repaint them. they are not sure if that fixes the problem. i couldnt trust their theory. disconnecting door connector (all 4) is costing (~220 each)more than replacing the handles(~1000 total). i talked to some other dealers, they are not aware of this concept. i am confused what should i do to fix it permanently. btw, car battery is 3 yrs old (got from advance auto parts) and its not registered with the car computers. but they ruled out this as a cause for the drain issue. please advice.
Expert:  Roger replied 2 years ago.
Glad to help clarify. It is not uncommon for the door handle electrics to just fail and cause a drain. I have seen this many times. The door handle works by breaking and electrical field. If there is too much paint it can break the electrical field and cause the handle to send a signal to the CAS causing wake ups. The door handles are ordered by VIN color coded. Painted handles can cause problems. Let me double check to see if these come pre- painted or not. Can you send me the last seven of the VIN number? If they do not come painted then it should be done only by a BMW approved body shop. Too much paint can cause a problem. Just to clarify where all 4 door handled re-painted at one point?
Customer: replied 2 years ago.
vin - CK92054external body of the car is repainted(Maaco body shop). they painted and applied clear coat (i think they used a product which has paint and clear coat mixed). rear door CA was not working since sometime, only front doors works. i didnt bother much about it. battery drain started before the paint job( but car painted with in couple days of this issue started). if i get CA disconnected from doors, will it impact anything else?
Expert:  Roger replied 2 years ago.
Well, I found something interesting when I looked this up by VIN. On your vehicle it is NOT the door handles (outer portion) that are responsible for the comfort access. It is actually the door handle carrier that is the electronic portion responsible for comfort access. So the door handles being painted on this vehicle does not effect this. I am going to attach a picture of the part that is responsible for the comfort access. I am not sure if this is the part the dealer has quoted or they have this wrong. I think they are going about this the wrong way. This is usually caused by the comfort access component. On some vehicles it is the handle. On your vehicle it is the carrier for the handle. What the dealer should do is unplug the connection at the doors one at a time and monitor the sleep cycle of the vehicle. They only need to replace the door handle carriers that are causing the problem. It would be very unusual for this to be all 4. Usually it is the driver and/or the passenger front. If they can narrow this down it would cost a lot less.