Door locks/alarm not working properly

Tiny
KATSMERCEDES
  • MEMBER
  • 2004 MERCEDES BENZ S500
  • AUTOMATIC
  • 190,000 MILES
Hi, my doors won't lock with the alarm remote. The alarm turns on but doesn't lock or unlock the doors you have to manually lock the doors by hand. Also the passenger seat won't move anymore. How to fix so my doors lock automatically and unlock and how to fix the passenger seat to work again? Both problems happened at the same time.
Saturday, March 6th, 2021 AT 9:24 AM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This could be a couple things but the most likely cause is a door module. However, I am not confident that they are the same issue so the best way to go about this is figure out one of the issues and if it fixes the other then that is great. If it does not then we will need to tackle that issue.

So let's figure out why the power locks are not working. Just to be clear, they will not work with the remote but will they work on the door switches or do you have to manually lock them at each door?

The way this works is the remote puts out a signal and the receiver picks it up and sends it to a door module for it to send the signal to the locks to open.

So we need to find out if the module is getting this signal. We do that by monitoring the voltage on the door modules when you are pressing the button but let's start with finding out if the power locks work at all.

If they don't then I suspect we don't have a remote issue but just a power lock issue.

Let me know and we can go from there. Thanks
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Saturday, March 6th, 2021 AT 6:51 PM
Tiny
KATSMERCEDES
  • MEMBER
  • 2 POSTS
I have to manually lock each door but the remote does activate the alarm. So if someone tried to open my car it makes a loud whining noise.
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Tuesday, March 9th, 2021 AT 11:05 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. So the way to figure this out is to go to the actuator and find out if the voltage is being supplied. If not we need to start suspecting the PSE module is the issue.

I attached the info below on this and we can go from there.

https://www.2carpros.com/articles/door-panel-removal
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Wednesday, March 10th, 2021 AT 6:23 PM

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