Key dead,spare key not working and car won't lock or unlock

[Frontstep]

Just to be clear does the fob sender flash strongly when aimed at digital camera or phone.

 

[Coupe-kompressor]

Yes there's a strong red flash when I press the fob at my phone xxx

 

[Mark@RMK]

Its either - This is FACT and no guess work..

The Antenna for the RF signal - Try the radio, does it have bad reception? if so then its the aerial on the back windscreen.

The Ignition switch ( EIS/EZS ) Depending on which type it is ( Newer version on some 2002 onwards ) fails inside in the cold. - Solution is new ignition switch.

I work and fix keys all day long and this is most common problem.

Ignition switch is £400 ish plus fitting at MB
Aerial is £251 plus fitting at MB

Hope this helps!

Mark

 

[Alex Crow]

As the fuse is OK, on to my next suggestion - the antenna connection has come unstuck from the rear screen.
It can be stuck back on, no parts required. There is a thread about this on the forum somewhere.
This is really common on the coupe, and can also happen on the estate too.
In my experience, antenna amp failure is actually very rare.

 

[television]

I think that the jump starting may have done something here,, even if the long range does not work the IR close range would work. You can only see the IR beam through a camera, the RF you need something else

 

[Alex Crow]

True enough Malcolm, but as we know, the IR sensors very often don't work anyway!

 

[television]

True enough Malcolm, but as we know, the IR sensors very often don't work anyway!

Not so sure on that,, I have had 6 keys all sent within the last 2 weeks and they were all IR faults, I only repair the IR section and all owners happy and in their cars

 

[Alex Crow]

I am talking about the DAS3 keys Malcolm, most people do not even know they also have an IR function with sensor on driver's door for convenience/comfort operation of windows etc.
I would estimate that at least 1 in 3 do not work (DAS3 driver's door IR sensors), and yes I have checked IR output on the keys.
We have discussed this before, and it was suggested to disconnect/reconnect the door sensor, which very often works!

Which type of keys are you talking about Malcolm?

 

[television]

I am talking about the DAS3 keys Malcolm, most people do not even know they also have an IR function with sensor on driver's door for convenience/comfort operation of windows etc.
I would estimate that at least 1 in 3 do not work (DAS3 driver's door IR sensors), and yes I have checked IR output on the keys.
We have discussed this before, and it was suggested to disconnect/reconnect the door sensor, which very often works!

Which type of keys are you talking about Malcolm?

I only mainly fix DAS3 keys, and a few with the odd flip out key both single button and 2 button

 

[Alex Crow]

So you had 6x DAS3 keys in two weeks that only had IR faults?

But these peoples cars were unlocking and locking OK on the RF?

So they knew about the convenience/comfort feature not working on the IR?

 

[television]

So you had 6x DAS3 keys in two weeks that only had IR faults?

But these peoples cars were unlocking and locking OK on the RF?

So they knew about the convenience/comfort feature not working on the IR?

I no longer have a spectrum analyser, the keys come to me as they are not locking the car and sometimes not starting either.

I do not test the RF section, only the IR,, it is quite possible that some things are shared as through hole plating goes down and open circuit. There is no such thing as a circuit for these things, I do not have the time to write one down backwards, there is no point

 

[Alex Crow]

Sorry Malcolm, with you now, you are talking about IR faults preventing keys communicating with the EIS - very common indeed, I quite agree.

Back to the locking issue, this car starts OK, but does not remotely lock/unlock on RF or IR.
My point is that I often see the IR convenience/comfort feature not working on DAS3 cars anyway (where the RF and EIS communication are fine, and with no customer complaints), so we ought not to draw too many conclusions from that fact in this case.

 

[television]

Sorry Malcolm, with you now, you are talking about IR faults preventing keys communicating with the EIS - very common indeed, I quite agree.

Back to the locking issue, this car starts OK, but does not remotely lock/unlock on RF or IR.
My point is that I often see the IR convenience/comfort feature not working on DAS3 cars anyway (where the RF and EIS communication are fine, and with no customer complaints), so we ought not to draw too many conclusions from that fact in this case.

I thought the owner had 2 keys and had tried them both, I am not drawing any conclusions on this, but after a jump start on one of these.. I repair many more keys for locking than starting, 124 cars are IR only I believe, only a 50% success rate with these,, they can emit but not recognized by the car, possibly a Xtal has shifted, I will never know why folk will hang 20 keys on the same ring and wonder why the EIS switch fails, plus the vibration when the whole bunch is thrown down is not good

 

[Alex Crow]

..................I repair many more keys for locking than starting.....................

If you mean DAS3 keys surely you are talking about RF fault with locking, rather than IR faults?

As I said before, very few people with DAS3 cars even know about the IR locking function, and so would not even know it has a fault.

 

[television]

If you mean DAS3 keys surely you are talking about RF fault with locking, rather than IR faults?

As I said before, very few people with DAS3 cars even know about the IR locking function, and so would not even know it has a fault.

Please do not keep telling me what I do or even more what I am doing, I do know what I am doing and how to do it, as I said before with through hole plating faults it can all go down on the key.

 

[Alex Crow]

To the original poster, if you can give us the answer to Mark's good question about radio reception that will be very helpful, we are wondering if the car has got an RF reception fault.

Also, changing the batteries between keys is worth a try.

 

[television]

The sad thing here is that you assume that if the fuse is not blown the amp is OK. This is very bad thinking for these things can have 2 SMD fuses inside, but apart from fuses there is 100's of reason of why an amp can fail. I have spent my life working on such things, and until recently I worked to component level. What you have found with failures does not necessarily tie in with the rest of the world. We had many threads that I have been on here all solved. Yes the window can lose contact with the connections.

Its the same as when I tried to explain about the speed sensor faults that where the can is giving no or incorrect information from the brake lamp switch.

On a piece of apparatus that contains multi circuitry where speed signals are shared, if you have the full circuit diagram,, of the part in question and I am not talking about those in WIS for they are not circuit diagrams they are wiring diagrams. with a circuit diagram you can scope up the various chips in and out to see the actual signal and what has happened to it. or simply see where what you are looking for starts and stops. It is not my job to teach basic electronics on here, and I do not try too, any real electronic engineer would understand what I try and say without being taken to task over everything that I try and explain as simply as I can.

 

[Coupe-kompressor]

Ok sorry for late reply, last time I used the metal key was this morning to open the car door as the fob wasn't working, mysteriously enough it then began to work, then decided not to work, then decided to work again..
It's driving me mental. I phoned Mercedes and they said I might need to reprogramme the key which costs £80-90. Thing is it works one minute not the next. I recently had my windows re tinted.. And thought that might have been the reason.. But again why would it work sometimes and not other times?? X

 

[Coupe-kompressor]

Oh, and my radio works fine :-/

 

[television]

If the windows are tinted, this can stop the remote RF from working,, have you tried with the key very close to a door handle to see if the IT section is working