Central locking failed e320 cdi w211

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Warpa

New Member
Joined
Jun 20, 2020
Messages
10
Location
Southampton
Car
E320 cdi and CLK320 V6
Hi, new to the group and I know this has been covered before, but none of the fixes have worked.
Fuses are all good, key fob batteries light up, amp, siren, rear washer, radio all fine.
The car is new to me and previous owner said it only just failed. Is it possible both keys have failed?
Locking is fine using the button on the dash and the key starts the car fine.
Is there anything I have missed? Oh, no breaks in any of the wire things on rear and side windows and resetting the keys didnt work. Only other info I have is that the car was rarely used which is why he sold it.
 
Hi and welcome. The fob light indicates that the battery is working however it doesn't mean that the key isn't faulty. The unlocking part is completely separate from the starting of the car. Which method have you used to pair the fob with the car?
 
Locking feature is working also two ways; RF signal or IR signal. RF functionality you probbaly have tested failing since door are not opening. IR sensors are in door handles and (IIRC) inside mirror, you can test test pointing key to drivers door handle under~2m and press the button.
 
Hi and welcome. The fob light indicates that the battery is working however it doesn't mean that the key isn't faulty. The unlocking part is completely separate from the starting of the car. Which method have you used to pair the fob with the car?

Insert key turn to 2, hold lock button and remove, while holding lock press unlock 5 times.
The infa red doesnt work either.
 
Try this, slightly different to your method

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I've got what I believe is an interesting and close to finding the fault bit of news.
Central locking and tailgate opening is fine using IR, if I lock the car and open it by putting arm in window to set the alarm off the indicators flash but no siren.
I've checked and replace fuse number 7 the 7.5 amp and it was fine. Now clearly there is a fault or short with the siren, but no fuse blown?
 
Have you checked the continuity of the red/yellow (from memory) wire that goes from the rear sam to the amplifier module above the nearside rearmost window? I must have seen a dozen or more over the years where there is no continuity on that wire. I usually run a fresh cable to solve it, as unpicking the loom is difficult in that area.

The siren thing you described points to a dead siren. Very common, but doesn’t affect the locking in my experience
 
This car is now giving me brain ache! The radio has now packed up. I have had a look at the fuses and they are fine, fuse 5 by the steering column is missing and no holder for it to go into.
I find it strange that the radio was fine and now isn't after my mechanic had been checking fuses for the central locking fault, did he knock a fiber optic lead.
This car has 121k miles and a full Mercedes Benz service history up until 2 years ago, in which time it covered just over 1k miles (hence why the previous owner sold it)
I do have a Merc bloke coming out on the 9th for the central locking, will get him to scan for the radio fault assuming he has a proper diagnosis tool. Mercanix is the company and they look pretty good.
 

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