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Questions about Locking Doors

2401 Views 24 Replies 7 Participants Last post by  asianml
I just found out that when I open the tailgate using the keyfob, it doesn't lock back when I close it. It doesn't matter whether the doors were locked using the keyfob or manual lock button. Is it supposed to be this way? I'll check to see if the security system still stays armed after opening the tailgate. In my other MB car, the trunk will lock back and the security system reactivated.
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When my rear hatch actuator broke (cheap piece of plastic), my door will not lock anymore. It could unlock the hatch if I locked it manually from the inside since the broken actuator could still push but not pull on the lock mechanism.

Are you saying that you cannot lock it manually from the inside cabin handle either..? If it was the actuator, normally you will still be able to lock it manually from the inside.

Does it make any sound when you try to lock/unlock the hatch..?

If you replace the actuator, you need to be careful and get the right mechanism model/part with the right sensor connection. Otherwise your alarm system and lights will not work correctly as it happen to me with my former 2001 ML 320.

This is what I always do all the time, I open the hatch door and then I lock all the doors which will lock the rear opened hatch door, and then when I picked up all the items I need, then I close the hatch door and the alarm will blink 3 times and all the doors and hatch doors will remain locked..

When I go home after work, I will test your steps by locking and arming the ML alarm, and then opening just the rear hatch door and then closing it to see if it locks itself...

I tried locking and arming my ML, then using the remote to unlock just the rear hatch door, and then closing the hatch door to see if it lock.. It did not lock, I had to lock with the remote to arm the alarm and to lock the hatch..

Darkman wanted me to try to see if the automatic locking system got activated when the vehicle was locked and armed and one opened just the rear hatch with the remote hatch unlock button.

He thought that when the hatch door got closed, then the automatic locking system should lock the hatch and arm the ML alarm system after some time. Just like when you unlock the vehicle, but without opening any doors, which causes all the doors to be locked automatically after some time.

Strange, if my hatch door is open, with all other doors closed, and I use the remote to lock the vehicle, then all my doors and including my tail gate will lock, and if I then close the tail gate, then the tail gate door remains lock and the lights blink 3 times and the alarm gets activated.

Seems like your tail gate don't lock when it is open. I like the tail gate's ability to lock while it is open, like other doors do, because then I can just close the door and walk away when I finished unloading..

Thanks and you are right Asianml.. [:)] Only the front door will not lock if it is open and all other doors including the tail gate will lockup when pressing the remote control lock button..

And just to confirm the differences, if my ML is completely locked and then I unlock the tail gate with the remote tail gate unlock button and then I open it, then when I proceed to close it nothing will happen and the tail gate will not lock or be locked by the automatic locking system. If I open the tail gate, the alarm will not sound since the vehicle alarm didn't get activated.

If my ML is completely locked and I unlock only the tail gate and open it, then if I lock the vehicle using the remote, the tail gate will lock and only when I close the tail gate door, the ML alarm will be activated and the tail gate will remain locked.

I just spent around 20 minutes playing with all the possible combinations..

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On my former 2001 ML 320, when my rear hatch actuator broke, I replaced it, but I noticed that the new actuator did not had a wire like the original had, and the vehicile was arming even though the rear hatch door was opened since it somehow thought that all the doors were closed. When I got the new actuator from the dealer, I was careful to ask the sale parts guy to double check the model and the part. Even with that, somehow, I got the wrong part..

My new 2005 ML 500 locks (with the remote) the hatch even if it is open, and if I leave the hatch door opened(without opening any other door and even if I use the remote hatch unlock button) the alarm will not arm since it knows that the hatch door is open (sensor in the actuator mechanism)... It will arm the alarm if I close the hatch and it will keep the hatch locked, if I had previously locked it with the remote before closing it.

Did you replace your rear door actuator..?


rudeney said:
I have a similar issue with my tailgate. My tailgate does in fact lock securely, but only if it is closed and I press the lock button on the fob (or use central locking or automatic locking at 10mph). The problem occurs when I lock the doors via the fob with the tailgate open. If I do this, then the alarm actually sets, even with the tailgate open. When I close the tailgate, it does not lock. If I then re-open the tailgate, the alarm is triggered. My tailgate also does not re-lock when closing it after using the “trunk” unlock button on the fob.

My understanding is that the tailgate should in fact lock if closed when the alarm is armed. I believe it should also re-lock and re-arm the alarm when closing it after using the “trunk” unlock button on the fob. When I was playing around with Carsoft, I was able to read error codes on the AAM and discovered that there is an error code on the tailgate actuator, so something is in fact wrong. I removed the trim panel and tried to see what was going on, but I really couldn’t tell. Everything seems to be connected correctly, but something is not getting a signal when the tailgate is close (either that or the system always sees the tailgate as closed when it is actually open).

One day, when I have more time, I may look into it some more.
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