KEY FOB

[mercedesc220]

:cry:

Guy's something really weird is happening.

Every 2 or so weeks when i go to unlock the car with the remote key fob in my C220 it trips out the alarm & Immobliser.
I then need to take the battery lead off the car leave for 5 minutes and then change the remote fob battery to new one for it to start working.

I think there is something really wrong in the kay fob for it to be killing the battery every 2 weeks. the car is hardly driven twice a week.

Do you really think it can be the key fob :?:

HELP PLEASE....

 

[mercedesc220]

:cry:
Anyone Please

 

[stuarth]

Possible cause

In general, there is a procedure for changing batteries in the key fob and also one for locking and unlocking and changing or reinitialising codes (which you now need to do having disconnected the battery. I don't know what this is for your car so I would ask a garage frankly. But, yes, all this could come from the key fob believe it or not...

 

[joe bloggs]

when you say it trips the alarm do you mean the remote does'nt work and you have to open manually?
When the remote batteries are getting low the green/red lamps will flash together when locking / unlocking, this upsets the dealer fitted alarm as it does not know whether to switch on or off.
Is this the older car without the red/green lamps and a seperate key and alarm fob, or the newer flick out key

 

[mercedesc220]

Hi,

Sorry i was not clear.

The car has both green and red lights, When i say trip when you unlock the car both lights flash but the door locks still open, but when you try and start the car you can not due to the immobiliser still active.

Hence i then need to disconnect the battery, leave for 5 mins, reconnect, change the batteries in the reomote and hey presto its working.

 

[jberks]

Hi,
My C220 used to do the same thing sporadically. I am not sure how it knows the battery is low, but it seems to send the signal incorrectly from time to time. There was usually nothing wrong with the battery and changing it would make no difference. The battery will last years so I don't think you are gaining anything on this front and all changing the battery is doing is giving the system time to reset. In the case of mine, I would lock the car, the red and green lights would flash and the indicators (attached to the alarm) would flash for ages. It would set eventually so I often just walked away. However, if I unset and reset it a couple of times, it would set ok (single light flashing). Sometimes I found that just waiting 30 seconds or so before attempting again made a difference too.

It does sound like the two lights flashing are upsetting the aftermarket alarm as Joe says, (and as mine did) but generally a couple rounds of re-locking and unlocking the car until the unlock works correctly should clear the alarm and you'll be on your way without having to get the spanner out.

 

[joe bloggs]

The double flashing is a function of the c/locking when the signal from the remote becomes weak, ok in germany, but uk spec scorpion alarm needs either red or green to operate and will not release when both signals are received, new remote batteries (check / clean remote battery terminals) should sort it out, you cannot tell how long they last, sometimes years, others (taxi's etc) who are using the remote 20-30 times a day will need them much sooner, we normally change them at every B service.

 

[mercedesc220]

The remote is only used twice a week, thats what makes me feel that the remote is faulty.

Been testing my theory over the last 2 weeks.

I have been taking the batteries out of the remote when the car is not in use and HEY PRESTO (touch wood) they have been fine. :lol:

 

[jberks]

Out of curiosity, have you cleaned the rear view mirror and pointed the transmitter directly at the mirror?. If the signal is having to bounce around the car first, that could result in a weak signal indication.
I've had a couple of remotes replaced as the buttons do wear out. It usualy means that they don't work at all, rather working all the time.

If you have access to a camera with an IR function (some Sony models) you can use it to see whether the IR bulb is still lit when the button is not pressed.

 

[philharve]

Remote keys ... are they reliable?

I am wondering whether the M-B electronic key fobs and immobiliser are reliable?

The reason I inquire is that my brother purchased a Renault Megane (two models older than the latest 'shake-an-ass' model, the one with the near vertical rear window). His remote locking system let him down 4 times in the past year, twice with me as passenger. I am not impressed by the Renault system which is known to have a weakness.

It seems the Renault uses a cyclic coding system that can get out of step and will prevent the car from being started. You can still get inside though, a blessing if it's raining or very cold. Fortunately, the Renault immobiliser can be overidden by hitting a particular sequence of controls on the facia, a secret known to very few.

I have two remote keys with my M-B and I thought I read somewhere that the internal battery is charged when inserted in the ignition socket, consequently their life is measured in years, not months.

Touch wood, I've had no problems with my M-B immobiler or key fobs. If I did, is there an immobiliser override on M-B cars or is that a question no one will answer?

My fobs have a single red LED which flash once whenever one of the 3 buttons is pressed. Is the red-green LED fob a later design?

REGARDS Phil

 

[pascal]

M...S220
It seems fairly obvious to me that your RC is draining the battery. If you
do not have a second one or emergency one, try taking it apart gently and
see if any dust or grime has entered it. Try to clean it with a pressurised
camera cleaning aerosol.
Failing this, It looks like a trip to MB for a new fob (expensive, for any car)
(not just MB)

 

[jberks]

Phil,
I can't comment for everyone else, but I have had the same three button key for 4 years now (plus 1 year as a demo before I bought it) and haven't so much as replaced the battery. In the same amount of time, I replaced 2 key fobs (flick type) for my C. So I guess its one thing Merc improved!
The red-green led was on the earlier - pre 98- cars (not the remote). They have changed slighly since mine with a smaller key but the basic design is the same.