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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53014
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Key will not open or close doors, opened door with metal

Customer Question

key will not open or close doors, opened door with metal key, alarm went off. Can start car and drive with alarm commong on and off for about 5 minutes. When pressing the open on the key the red light indicator still goes on. I was hoping dead key battery, does not look like that
JA: Did you test the battery with a voltmeter? And have you ever changed one before?
Customer: Have not tested the battery, can do so, i have a voltmeter
JA: What is the model/year of your Mercedes?
Customer: 1998 e320
JA: Are you fixing your E320 yourself? What have you tried so far?
Customer: just happened for the first time, of course in a grocery store parking lot, drove home it is quiet now, the key is still dead
JA: Anything else you want the mechanic to know before I connect you?
Customer: been having trouble with the windows working on and off as well as the seat adjustment
Submitted: 9 days ago.
Category: Mercedes
Expert:  Marty replied 9 days ago.

Hi, my name is***** will most likely be a fault with the PSE module for the door locks and alarm. The module is located under the rear seat cushion next to the battery. It is inside a foam encapsulation. Usually you will find that water has found it's way into the module and has shorted it out. This would also account for the other problems you are having.

Let me know if you have any questions. Kindly rate my service in order for the website to credit me for helping you.

Customer: replied 8 days ago.
What do you do about it? I certainly can locate it. As a old aircraft elec tech sometimes it is corrosion? Otherwise can this part come from the salvage yard and replaced without needing a mechanic?
Thanks this makes a lot of sense.
Customer: replied 8 days ago.
Going out of town in one hour back next week, can we restart then?
Expert:  Marty replied 8 days ago.

Hi Bill, it's usually best to just replace it rather than trying to repair the module. You can usually find new and used ones for sale on ebay.

Expert:  Marty replied 8 days ago.

Let me know if you need anything else.

Customer: replied 7 days ago.
Any thing about replacing it?
Expert:  Marty replied 7 days ago.

No, it's plug and play.