Trunk doesn’t lift up
Thread Starter
Newbie
Joined: Apr 2021
Posts: 6
Likes: 1
2009 Mercedes Benz s550
Trunk doesn’t lift up
Hello everyone!
This is copied from my previous post. I finally found out this logic board and got a used one from eBay.
I put it in instead of one I had, the buttons on a trunk lid to close and to lock lighted up so it works.
I closed it with a button, opened with an outside handle it lifted up, AND then next press of a button did nothing. I can hear sound in some module on a right side(next to right taillight) but it won’t close.
Disconnecting it for a minute and plugin it back in somewhat resets it. It behaves exactly same after each reset - closes, opens and that’s it.
BUT the buttons are still lighted up, and lock button actually locks the car but won’t close the trunk lid.
Any suggestions?
Thank you!
I have a 2009 s550 4Matic (Since I am in the US it is long version). Recently, I started noticing my trunk wasn't working correctly.
The issue was in the following: after each car wash, my trunk would open but wouldn't lift up or down with the press of a trunk "Close" button on a tailgate. After few days it was ok again. But after the last car wash, the trunk stopped lifting up or down at all, and tailgate "close" buttons were not lighted up.
I took all the interior out and checked the right side of the trunk where the hydraulic lift motor is located. Not surprised; everything there was wet. There is this "case" that holds a hydraulic lift motor(on pics I am attaching it is on a left side from the red circle with white zip tie around), and it has this kind of industrial foam. It was soaking wet, then the logic board where this motor is connected was also wet(including connector and board itself). I had a leak between the right taillight and body panel, did some magic there, hopefully, fixed.
With the amount of rust hydraulic lift motor had, I assume that leak was there for a while, even before I got the car(I got it in August of 2020).
Dried everything up, put it back together, and - nothing...
The issue was in the following: after each car wash, my trunk would open but wouldn't lift up or down with the press of a trunk "Close" button on a tailgate. After few days it was ok again. But after the last car wash, the trunk stopped lifting up or down at all, and tailgate "close" buttons were not lighted up.
I took all the interior out and checked the right side of the trunk where the hydraulic lift motor is located. Not surprised; everything there was wet. There is this "case" that holds a hydraulic lift motor(on pics I am attaching it is on a left side from the red circle with white zip tie around), and it has this kind of industrial foam. It was soaking wet, then the logic board where this motor is connected was also wet(including connector and board itself). I had a leak between the right taillight and body panel, did some magic there, hopefully, fixed.
With the amount of rust hydraulic lift motor had, I assume that leak was there for a while, even before I got the car(I got it in August of 2020).
Dried everything up, put it back together, and - nothing...
I put it in instead of one I had, the buttons on a trunk lid to close and to lock lighted up so it works.
I closed it with a button, opened with an outside handle it lifted up, AND then next press of a button did nothing. I can hear sound in some module on a right side(next to right taillight) but it won’t close.
Disconnecting it for a minute and plugin it back in somewhat resets it. It behaves exactly same after each reset - closes, opens and that’s it.
BUT the buttons are still lighted up, and lock button actually locks the car but won’t close the trunk lid.
Any suggestions?
Thank you!
Last edited by Maxvel_ua; Aug 10, 2021 at 09:15 PM. Reason: Typo
Junior Member
Joined: Dec 2020
Posts: 16
Likes: 6
From: Newport Beach, CA
2011 Range Rover SC Autobiography Black Edition
Hi Maxvel_ua,
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
Thread Starter
Newbie
Joined: Apr 2021
Posts: 6
Likes: 1
2009 Mercedes Benz s550
Hi Maxvel_ua,
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
I sent you DM.
Thank you,
Max
Junior Member
Joined: Dec 2020
Posts: 16
Likes: 6
From: Newport Beach, CA
2011 Range Rover SC Autobiography Black Edition
Hi Max,
I apologize for the delay. I have sent you instructions to correct this issue. Please let me know how it goes and if there is anything else I can clarify or help you sort out.
Thank you,
Christopher
I apologize for the delay. I have sent you instructions to correct this issue. Please let me know how it goes and if there is anything else I can clarify or help you sort out.
Thank you,
Christopher
Newbie
Joined: Aug 2025
Posts: 2
Likes: 0
Hi Maxvel_ua,
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
I just so happened to have had this exact issue, so I feel that I may be able to help you.
You've discovered some moisture beneath the trunk lining of your vehicle and apparent water damage to the trunk lid control module (LU: A221 870 61 85). So—you go on eBay, type in the part number, find a matching control module, and swap out your corroded one with the new, used one. Then, you test the automatic trunk control functionality—and it works—but only once.
Unfortunately, this trunk control module is VIN coded. Using a STAR diagnostic computer will reveal an error code that states the VIN of the control module you have just installed does not match your vehicle.
I became a little discouraged when I found this out, especially since I gathered from other forum members that you cannot remedy this issue without using online SCN coding. However, digging through the developmental functions in my STAR diagnostic computer, I found a way to have the control module cleared so that it can relearn my vehicle's identification number.
If you are located in Southern California or have access to a STAR diagnostic computer, I would be more than happy to help you figure this out. Otherwise, I am ambivalent about posting instructions on this public forum in fear that it may be against the rules to share tips about using a counterfeit diagnostic computer. Let me know via private message.
Best wishes,
Christopher
Last edited by ferodrigu; Aug 1, 2025 at 10:26 AM.
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Newbie
Joined: Aug 2025
Posts: 2
Likes: 0
Whether it is or no the new control unit is vin locked so it needs to be erased and then initial start up so I can write my cars vin. Just cant seem to find how to do it.
Last edited by ferodrigu; Aug 1, 2025 at 01:22 PM.
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