S211 2003 Key Fob Not Working

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toolman1954

MB Enthusiast
SUPPORTER
Joined
Sep 16, 2004
Messages
1,145
Location
Leven, Fife / Northampton
Car
2006 320 CDI Avantgarde . 1997 312d Sprinter
Hi,
Key Fob has stopped opening and closing the locks, also no AM radio and FM is weak.
I have changed batteries in the key fob, and checked the 7.5 amp,fuse 8, on the rear SAM that supplies the Aerial/ Antenna Amplifier.
Voltages on the 3 wires from Sam to A. Amp (Ign off ) were Red/Yellow 11.4, Pink/ Blue (radio on ) 11.96 and Grey /Yellow 11.70. I ordered a replacement Aerial amp from Ebay ( A2118202989) which came today (weds ). Took the dog for his walk this morning and Fob opened and closed locks, still no AM radio, LW or SW ....BUT Radio 2, Radio Scotland, and others previously missing, were now back.
So I checked the voltages when I came home. R/Y 12.49, P/B (radio on ) 12.12 and G/Y 10.00.
Postie arrived with replacement part, so fitted this and again measured voltages. R/Y 11.47... P/B 11.99 and G/Y 10.7.
FM radio working as normal, now some white noise on AM but no stations, Key fob generally not working still, although once or twice it did. Also I tried Syncing key to lock, but no great improvement.
So where to go next?
Most other cases of this seem to have been resolved with a replacement Aerial Amp, but obviously not mine.
I have used this very useful blog to assist and fault trace :-
JB Service: Mercedes W211 E 500 estate, 2004. RF unlocking the car is not working.
Useful comments welcome, Thank you

Steve
 
Is the car alarm in working order?

Dec
 
Well todays update :- took the dog down to the beach for his a.m. constitutional, and on the way back Radio 2 and Radio Scotland which had disappeared overnight and for the journey to the beach had now reappeared as if by Mercedes magic. I did a swift voltage measurement with Ign on and R/Y was 2.6, P/B was 12.1 and G/Y was 2.6.
8.30 pm, just a while ago, I went to lock up the car, flick the switch on the dash and use the key in the drivers door, before I got out I tried synchronising the key again. (Key in Ign on, key out , hold the lock and unlock buttons down till the red light flashes). Surprise surprise the fob locked and unlocked the car. So I have left it locked at the moment and will see what happens in the morning.
I had pondered in getting yet another Antenna Amp, as there is no proof that the replacement is good, but the only others on Ebay are in Germany or Lithuania. This afternoon while we sat in the back of the car, ( dog and I...teaching him electronics...) I had thought of even changing the rear N10/2 SAM unit.

@ Dec,
Thanks for your input, last time I managed to close the doors using the fob, the alarm did go off when I used the key, so at the moment I assume it works ok.

Steve
 
Well todays update :- took the dog down to the beach for his a.m. constitutional, and on the way back Radio 2 and Radio Scotland which had disappeared overnight and for the journey to the beach had now reappeared as if by Mercedes magic. I did a swift voltage measurement with Ign on and R/Y was 2.6, P/B was 12.1 and G/Y was 2.6.
8.30 pm, just a while ago, I went to lock up the car, flick the switch on the dash and use the key in the drivers door, before I got out I tried synchronising the key again. (Key in Ign on, key out , hold the lock and unlock buttons down till the red light flashes). Surprise surprise the fob locked and unlocked the car. So I have left it locked at the moment and will see what happens in the morning.
I had pondered in getting yet another Antenna Amp, as there is no proof that the replacement is good, but the only others on Ebay are in Germany or Lithuania. This afternoon while we sat in the back of the car, ( dog and I...teaching him electronics...) I had thought of even changing the rear N10/2 SAM unit.

@ Dec,
Thanks for your input, last time I managed to close the doors using the fob, the alarm did go off when I used the key, so at the moment I assume it works ok.

Steve

What you describe above is programming the remote to go from Selective Unlocking to Global Unlocking;

Selective unlocking… only the driver’s door and fuel flap unlock.

Global Unlocking… all doors, boot/tailgate and fuel flap unlock.


If the alarm siren is the original factory fitted unit then its now14 year old and worth testing for a full 3 minutes.


Dec
locking.jpg
 
Friday update,....... well as expected the fob did not unlock the doors, had to use the key, and as expected, the alarm went off. The journey to the sea front is not so far and Radio Scotland was there on the screen and still working. An hour later after his walk, still had to use the key to get in and Radio Scotland by name had disappeared and there was just the frequency on the screen. I had a quick look to see if Radio 2 was there, but that had gone and when I went back to find Radio Scotland, that also had completely gone.
Stopped off at the supermarket for 10 minutes, and when I got back into the car, Radio 2 and Radio Scotland had re appeared, but no open/ shut locks with the fob. This is starting to now annoy me. I am sure there must be some link with the radio stations going AWOL and the fob not working. I have now got a copy of WIS to try to get a wiring diagram of the Ant Amp and rear SAM unit.But need some help with this . I will open a separate thread for this.

@Dec, Thank you for your continued input. According to the service history the alarm was replaced in May 12, and today it was certainly working when I opened the door. The fob setting for global and selective was something I did not realise and actually has no bearing on the issue in hand. I really need to change it back as now everything is not being unlocked , so thank you for that.

Steve
 
You have classic symptoms of a faulty alarm siren, first you have central locking problems, next you have radio receptions issues, and then you start discussing electronics with the dog!

I’m not suggesting you do this, but if it were me, I would unplug the alarm siren, just to eliminate it from the inquiries. Something to try if all else fails.

If the car isn’t unlocked by the remote, then the alarm may still be armed, so, if it is unplugged while it is armed then it will go off.

A 5 ½ year old siren should be ok, unless it ever had a very long period without a car battery powersupply to keep its internal rechargeable batteries toped up.


Dec
 
Dec... Thanks for your continued help.
Tomorrow, I will go down the local garage and see if he can spare some time and a ramp in the next few days. I will pull the o/s wing liner, then disconnect the siren and see if there is any joy in the fob working in doing that.
I actually want to re piston ring the Air Pump for the suspension, so I can perhaps kill 2 birds at the same time.

Steve
 
Saturday, another day, another dinar. So local garage was busy, so I found a couple of knee braces and jacked up the car, removed the liner, and disconnected the alarm. No difference, I removed the carrier and the alarm. The alarm looks pristine with no rot, and the wiring is all good. Had it looked cruddy, I would have fitted a new alarm. So no further on really, except after I had packed everything away and was just messing around with the fobs (I have two of these ) they randomly did lock and unlock the doors a couple of times, but the problem is certainly not sorted and at the moment, no idea what to try next.

Steve
 
I would suggest you check the condition of the aux battery under the pollen filter n/s by the bulkhead.
If its not been changed in a while that could well be your problem.
Circa £75 from the dealer.
 
@ AMGeed....Thanks for your input, not looked at that yet, was replaced a few years ago according to the service history, but will gladly look at that tomorrow and stick the Fluke on it. Thanks .

Steve
 
Sunday, 8.00 am dog walk time, and surprise surprise, the door locks opened by pressing the fob. They would not lock, nor would the indicators flash when open button was pressed. Then as I started car up the "convenience functions off " warning on the dash came up. Long time since I had seen that, but perhaps because tailgate had been open for lots of time yesterday when I was accessing the siren, then that might account for that. Plugged in my fag lighter voltage meter, and with the heated seats on ( f. cold up here this morning, chilling sea breeze) voltage was 13.5 volts, I will just leave that in for a day or so and monitor voltage.
So, this conveniently leads me onto the Auxiliary battery, housed underneath the pollen filter. Voltage on that was 12.62 in circuit, and with both positive and negative leads off was still 12.62. So it would seem that is not the culprit, I do wish the culprit would make itself known !!
I was thinking on how I can check the R.F. that is emitted from the key. Then reproduce the RF by the Ant Amp. From the J B service link in my first post he is using a radio up in the 1600's to see if there is any signal. At home I have a radio that will do 0-30 Mhz and that has a spectrum signal analyser on it, but not going home till the 28th, and I would like to get this sorted asap. Thanks to all who have commented so far, onwards and upwards.

Steve.
 
I use to do the RF test with an old Scorpion fob. I was also able to pick up the sound of the remote up on my desktop computer speakers, might be worth a try on whatever computer you have in front of you or other computers around the house.

This is what it sounds like, sound file downloads... http://homepage.eircom.net/~decdec/fobsound.wma


index.php



Useful article on SAM’s… Mercedes-Benz SAM (Signal Acquisition Module) Explained


Dec
 
SOLVED.....SOLVED.......SOLVED

Well this whole episode has been a bit of a head scratcher.
I had tried 2 different aerial amplifiers, transmitting about 1 watt on 5Mhz to check the aerial reception and a couple of times over the last 3 weeks the Radio stations and key fob started working again and then in an instant stopped.
Sunday, now back in Northampton, I replaced the rear SAM N10/2, still no key fob / radio stations. I put the MB2 scanner on to check everything and lo and behold there was a code 9077. ( Communication with component Radio Signal reception of the Central Locking System is interrupted.)
So next I did a search on Google using this code. There was a thread on another MB site with exactly the same symptoms of my problem, and the fault was a broken red/white wire from the Aerial Amp in the roof which went to a green socket on the N10/2. Two people there had suffered the same fault.
So I pulled the plugs on the Aerial Amp and N10/2 and tested them for continuity and the buzzer on the meter was silent. I jammed a piece of wire into the two sockets and connected them back up. Radio working and key fob working .....hallelujah !!
I dare say that fitting the replacement SAM finally pulled the broken wire apart causing the fault code.
I have now just cut the red/white wire and spliced in a new section of wire.
Fitting the SAM seems to have caused another problem, that the fuel gauge is not working. I have posted another thread for some wiring help on this.
Thanks to all who came up with suggestions to help me resolve this problem.

Steve.
 
Glad to hear its resolved Steve. You're a better man than I am. Electrics baffle the hell out of me:wallbash:
 
AMGeed,
Thanks for your good wishes, I am learning slowly that these fine 211's seem to develop many electrical problems as they get older.

Steve
 
SOLVED.....SOLVED.......SOLVED

Well this whole episode has been a bit of a head scratcher.
I had tried 2 different aerial amplifiers, transmitting about 1 watt on 5Mhz to check the aerial reception and a couple of times over the last 3 weeks the Radio stations and key fob started working again and then in an instant stopped.
Sunday, now back in Northampton, I replaced the rear SAM N10/2, still no key fob / radio stations. I put the MB2 scanner on to check everything and lo and behold there was a code 9077. ( Communication with component Radio Signal reception of the Central Locking System is interrupted.)
So next I did a search on Google using this code. There was a thread on another MB site with exactly the same symptoms of my problem, and the fault was a broken red/white wire from the Aerial Amp in the roof which went to a green socket on the N10/2. Two people there had suffered the same fault.
So I pulled the plugs on the Aerial Amp and N10/2 and tested them for continuity and the buzzer on the meter was silent. I jammed a piece of wire into the two sockets and connected them back up. Radio working and key fob working .....hallelujah !!
I dare say that fitting the replacement SAM finally pulled the broken wire apart causing the fault code.
I have now just cut the red/white wire and spliced in a new section of wire.
Fitting the SAM seems to have caused another problem, that the fuel gauge is not working. I have posted another thread for some wiring help on this.
Thanks to all who came up with suggestions to help me resolve this problem.

Steve.
I have the same problem.How can I order the wires between the Aerial Amp and N10/2 ??
 
Hi,
I thought I had replied to this the other day??
However,
You can use any wire of the same internal diameter to re wire the aerial amp to the N10/2. Soldered wires would be better but a choc block strip may do for test purposes, the wire is not carrying any great current. I have plenty of wires laying about from old wiring harnesses, so I would have a look down the local scrappie, he might even give you a bit.
Other than that Halfords used to sell small reels of wire, or even a local car spares shop.
I hope you get it sorted.

Steve..
 
Hi,
I thought I had replied to this the other day??
However,
You can use any wire of the same internal diameter to re wire the aerial amp to the N10/2. Soldered wires would be better but a choc block strip may do for test purposes, the wire is not carrying any great current. I have plenty of wires laying about from old wiring harnesses, so I would have a look down the local scrappie, he might even give you a bit.
Other than that Halfords used to sell small reels of wire, or even a local car spares shop.
I hope you get it sorted.

Steve..
Thank you for the reply.I will try to sort it out
 

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