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Key will not ARM/UNARM (Lock/Unlock)

3594 Views 15 Replies 6 Participants Last post by  BMAN
I have a 1997 E320 with two keys. Just the other day, I could not lock the doors with either key. Figuring it was the batteries, I changed them in both and yet it still will not lock. I can start the engine and drive no problem, but I cannot lock the car!

I have tried turning the key one click (not turning the engine on) then removing the key and that did not work. Not sure how to resynch, but was hoping to avoid removing the battery terminal. Any ideas???

Thanks in advance.

Oh, and if you happen to see my car, please don't steal anything since my doors will be unlocked!!!
1 - 7 of 16 Posts
If yours is similar to mine it sounds like it might have something to do with the PSE system (the vacuum pump and lines).
Good suggestion iluvjesus, that will rule in/out what I suggested and if ruled out, point toward the keys. What I don't understand is why both keys went kaput at the same time.
I think I read that the pump is under the backseat beside the battery. Maybe you can run 12v directly to it and see if it runs that way.
I think that he should first try and re-sync the system and see if that helps before doing anything else
Good idea; it certainly can't hurt anything. Procedure for that can be found in the W210 DIY Stickys at the top of the page.
...The PSE seems to be fine...
There is another recent thread going where a member wants to troubleshoot his PSE. Do you know how to do that?
I thought you have already posted the link earlier, it is very helpful, thanks
Yes I did, but on another thread I think. You're welcome.
1 - 7 of 16 Posts
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