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Questions about Locking Doors

2400 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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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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AC_ML said:
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..

It makes me wonder if they were having problems with the actuators that had the closure sensor, so maybe that’s why the replacement did not have that wire?

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.

That seems to make the most sense – i.e. the hatch would act like any other door (except the driver’s door) and lock even if open, then arm the alarm when closed.

Did you replace your rear door actuator..?

No, I have not replaced it. I do plan to investigate it a bit more, though. And my existing actuator does have a wiring harness attached to it.
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asianml said:
Although I can't do anything about it, I will complain that the driver front door and rear tail gate won't lock like AC_ML described.

You should not be able to lock the vehicle at all (fob’s RCL or central locking switch) if the driver’s door is open. It’s a safety/security feature.
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