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My liftgate started acting up. It will open and close automatically, if I manually unlock it first. It will not unlock on it's on with remote, door, or hatch button. The motor works, I hear it working, but doesn't open.

If I manually unlock it from the inside and then hit the remote it will open. Hit the remote again, it will close and lock, but not pull tight, so the dash indicates it still open, interior lights, license plate lights, and third brake light remain on constantly.

I replaced the lock actuator with a new one today, same problem exists.

After it closes and locks, I hear a whirring sound, followed by a sctrachy sound, that doesn't sound right and it never pulls in completely. What could be the issue? Thanks!
 

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2010 GL450
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The mechanical latch mechanism is broken. Had this happen on mine a while back. You have to pull the plastic tailgate cover off in order to replace. All in all not too difficult.
 

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The mechanical latch mechanism is broken. Had this happen on mine a while back. You have to pull the plastic tailgate cover off in order to replace. All in all not too difficult.
Thank you so much for the reply. We started with that. I replaced it and had the same issue. I'll post the update of what it was separately. Picking it up from the dealer tomorrow. ❤
 

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My liftgate started acting up. It will open and close automatically, if I manually unlock it first. It will not unlock on it's on with remote, door, or hatch button. The motor works, I hear it working, but doesn't open.

If I manually unlock it from the inside and then hit the remote it will open. Hit the remote again, it will close and lock, but not pull tight, so the dash indicates it still open, interior lights, license plate lights, and third brake light remain on constantly.

I replaced the lock actuator with a new one today, same problem exists.

After it closes and locks, I hear a whirring sound, followed by a sctrachy sound, that doesn't sound right and it never pulls in completely. What could be the issue? Thanks!
UPDATE: So, I went ahead and ordered and replaced the lock. Unfortunately, I had the same exact problem when I was done.

So, all this started during tropical storm Ida after tons of rain poured on my car, I woke up to my born blasting nonstop and had to drive it to the mechanic. Long story short, everything that was malfunctioning returned to normal, except the lift gate. We decided to go through insurance due to the storm.

Water got into the car and got the SAM unit wet, THIS is the cause of my issue. First they thought the water was getting in from a broken rivet on the liftgate, but after replacement and excessive water testing, turned out to be the weather stripping needed replacing. (Side note I had some body work done not long ago and my side doors had the weatherstripping fall off on both doors and I'm wonder if the body shop was really the root of my issue)

Anyway, who can prove that, so they replaced the rivet and weatherstripping at my cost of $390, the insurance company picked up the water damage at $1400 for a new SAMs unit in the rear cargo compartment and my car rental for over 2 weeks now. I had a $500 deductable, so I'm at $890 for my cost in repairs. 🤷‍♀️ Thanks guys!
 

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No problem. The part where it doesn't pull in completely definitely sounds like the latch mechanism. If you hadn't already replaced it I would swear that was the problem. If I remember correctly there is a gear inside the mechanism along with the motor. The gear breaks and that's why you still hear the motor whirring away but nothing actually happens. When ours broke the tailgate wouldn't latch at all. Riding in the back with a rear full of groceries trying to hold the tailgate down while my wife drove home. That was an eventful afternoon.
 

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No problem. The part where it doesn't pull in completely definitely sounds like the latch mechanism. If you hadn't already replaced it I would swear that was the problem. If I remember correctly there is a gear inside the mechanism along with the motor. The gear breaks and that's why you still hear the motor whirring away but nothing actually happens. When ours broke the tailgate wouldn't latch at all. Riding in the back with a rear full of groceries trying to hold the tailgate down while my wife drove home. That was an eventful afternoon.
😱 That would be rough!! I know I would swear it was that too. But I think it was the electronics failing for that aspect making that noise. It still locked and unlocked manually and stayed shut, but wet electronics, how do you start?? As a matter of fact no one in our insurance approved network would touch it they all said you have to go to the dealer. Praying all is well when I pick it up! Also, another symptom I had was although it was shut and locked, the dashboard would read the liftgate was open and keep my license plate and brake lights on. These were things that developed since my post I guess as things worked further into the electric. 🤦‍♀️
 

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That sounds like possibly the rear SAM module. That's the computer that controls all of the electronics for the rear of the car. Have also had to replace that as well. The gasket around the passenger side tail light deteriorated and let water in the area where the module is located. There's no way around having to take it to the dealer for that though. They have to be coded to the vin number of the car in order to work. Mine kept telling me my trailer lights were out. I didn't have a trailer hooked up at the time.
 

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That sounds like possibly the rear SAM module. That's the computer that controls all of the electronics for the rear of the car. Have also had to replace that as well. The gasket around the passenger side tail light deteriorated and let water in the area where the module is located. There's no way around having to take it to the dealer for that though. They have to be coded to the vin number of the car in order to work. Mine kept telling me my trailer lights were out. I didn't have a trailer hooked up at the time.
Same here! Except the water was apparently coming in elsewhere. I happen to catch a video the morning I took it to the shop of the water trail to give them a start. Yup, rear SAM replaced. My trailer isn't hooked up either, would be awesome as a bonus if they fixed that error reading too!! Maybe that was the start of my SAM issues and they just escalated with the storm and heavy rain.
 
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