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Passenger window and door lock switches remain illuminated

Tiny
WHFH99
  • MEMBER
  • 2010 MERCEDES BENZ GL450
  • 4.6L
  • V8
  • 4WD
  • AUTOMATIC
  • 130,500 MILES
The passenger side, front door lock and power window switches remain illuminated after the vehicle is turned off. All three of the other door switches which are backlit while the key is on are no longer lit as soon as the car is powered down. The passenger front door is the exception. I have confirmed removing the 25A fuse, #26 from the right rear fuse compartment causes the switches to go dark. If this is an issue with the right front door control unit, is there a way to test this to confirm that before replacing it? I assume it is located behind the door panel, correct? Are these plug and play replacement? In other words, it does not need to be coded or programmed, correct?
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Monday, November 12th, 2018 AT 2:51 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Chances are the door module will need to be programmed. It also can cause the lighting issue as well. Here are the wiring diagrams and door module location so you can see how the system works. There is a light emitting diode that is run by the door module. Check out the diagrams below and please get back to us if the part needed to be programmed and the cost. Thanks for asking a new question, I was wrong the two problems are related, lol.

Check out the diagrams (below). Please let us know what you find.

Cheers, Ken
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Wednesday, November 14th, 2018 AT 11:38 AM
Tiny
WHFH99
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Hi Ken. Thanks for your continued help. How can I determine if the door module needs to be programmed? I assume I cannot do that myself and it requires some sort of diagnostic tool?
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Wednesday, November 14th, 2018 AT 11:50 AM
Tiny
KEN L
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  • 48,363 POSTS
The only way to see is to plug a new one in to see if it self initializes. You can try a used one as well. If not you need a scanner tool to program the unit. Please let us know.
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Thursday, November 15th, 2018 AT 11:01 AM
Tiny
WHFH99
  • MEMBER
  • 6 POSTS
I had a mechanic tell me that I could not use a used door control module as they are VIN coded and my only option would be to use a new one and would still need someone with a dealer-grade scan tool to program it.
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Wednesday, November 28th, 2018 AT 12:08 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Yep that is kind of true, I have heard of people plugging in used ones and they work. Must be a configuration issue on some. Let me know.
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Thursday, November 29th, 2018 AT 9:54 AM

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