Hi all

E300D - W210 - 1996
Single button keyfob with flip out key (only 1 fob / key), IR receiver unit in rear view mirror with red & green LED's. No LED's in door handles.

Doors lock & unlock OK using the key fob. Turn key in ignition to start engine, engine cranks OK, but no start. Red & green LED's flash alternately during cranking & for about 30 seconds whilst ignition is switched on.

I have replaced fob batteries & re-syncro key fob according to owners manual numerous times, but no luck. I have tried a number of the other suggestions I have found on thios forum to, but nothing seems to work.

Anyone have any ideas as to what the fault is & how to cure it?

Cheers
Garry

 

If the instrument pack warning lights go thru their startup check and the engine cranks it is important to understand whether you have a spark.
No spark may indicate that somehow the immobiliser is remaining active as you suggestossibly that your battery has gone bad BUT if the engine continues to crank OK this would be unusual.

Try disconnecting the battery overnight to "loose" all retained memory in the ECU's and have another go. This MAY just clear the problem.
However ensure you have your radio code otherwise you will have a further problem!
You may also have to renormalise your steering sensor etc (turn from lock to lock) etc. but this is straightforward.

Stuart.

 

Hi Stuart

Its a diesel, so no spark to worry about.
The car battery is fully charged & seems OK. It cranks the car over quite well. I've tried 2 new sets of batteries in the key. Everything seems to work as it should, except that the red & green LED's flash alternately, a few seconds after switching the ignition to position 2. The engine always cranks OK.
I am in the process of removing key & car batteries overnight, to see if we can't force a reset.
Thanks for the suggestions.

Cheers
Garry

 

OK guys, I disconnected the car battery & removed the key batteries overnight in an effort to clear any spurious codes that may have been there. This did nothing. I again re-syncronised the key, again same problem.
I took the key apart & found it has a small Philips transponder chip (13x5x2mm) just behind the infra red emitter LED. This is not connected to the batteries or circuit board in any way, so I am assuming it works the same as most other cars & simply sends its static I.D. to the ignition lock pick up coil when the ignition is switched on. Also, the only place to get a new key is MB, whereas most other manufacturers keys can be bought & programmed from any good locksmiths if you have a working key, or programmed via the car ignition switch. This would mean there is no facility in the car to reprogram or resync the chip, so the re-sync process does nothing for the chip / immobiliser, but simply aligns the infra red signal between the key fob & the central locking / alarm unit. OR IN OTHER WORDS, if you were able to totally remove the alarm / central locking system, the immobiliser would still work, as it is a separate circuit / system.
I cant work out why no one wants to program a key. There are keys in locksmiths around here with a flat bladed key & transponders built in that would fit, even though they have no infra red. Perhaps MB have some kind of 'patent', preventing 3rd parties from reproducing their systems.
Am I correct or am I barking right up the wrong tree?

 

Hi,

I now see that your key problem is linked to your start problem but in different posts.
I don't believe you mentioned this in your original post!

The keys are made by HUF and are now used by many manufacturers. They have a regional centre in Milwaukee. However the security electronics are MB and use components from several manufacturers eg Bosch and Hella.

Not conversant with how the immobiliser works on a diesel. Presumably it cuts the fuel somehow in the distributor.

Since the key will open/close the door locks the DAS module must be receiving the remote signal from the key. Likewise the engine cranks so I must agree that it is the immobiliser although I'm not sure whether the immobiliser SHOULD isolate the starter or not. I would have expected it to, so this may be significant.

Suggestion.

Security is handled by the PSE (Pneumatic security) unit which also controls the locks via the door switches. Does your security system work correctly? i.e. if you burgle the car ...lock it and open door thru open window... or jack the car (one wheel), does the alarm go off? If not then I would consider it could be the PSE.
The EIS (electronic ignition switch must also be high on the list since it is this that "communicates" with the key once in the ignition switch. When the key is placed in the ignition switch do certain services work that would suggest that the key recognition system is working ok?

Sorry I can't help anymore but am interested in whatever the outcome is.

 

What ever came of this I have the same issue on a diesel?

 

ttt

 

Ok.

I eventually purchased a new key for £100+ VAT from Medway Auto's in Rainham, Kent, England. This was about the cheapest I could find.
However, the reprogramming sequence they gave me is totally different from what I have in my vehicle handbook, so try this first;

1/. With the doors & windows locked for at least 60 seconds & you on the
outside, open the doors using the infra red button on the key aimed at the
mirror.
2/. Get in & lock the doors using the infra red,
3/. Switch off & remove the key.
4/. Lock the doors using the infra red button, leave until the mirror LEDs either
flash alternately, go off or only one flashes/stays on (no more than 10
seconds). Unlock the doors using the infra red button, leave until the mirror
LEDs either flash alternately, go off or only one flashes/stays on (no more
than 10 seconds).
5/. Within 30 seconds, put the key into the ignition & turn to position 2, leave
until the mirror LEDs either flash alternately, go off or only one flashes/stays
on (no more than 10 seconds).
6/. Switch off & remove the key.
7/. Get out of the vehicle & lock using infra red button. Wait 60 seconds or more,
unlock using infra red & see if car will start (you'll know because the LEDs
shouldn't flash if successful)

Heres another programming sequence I discovered by accident & works better if just re-sequencing the key.

1/. Sit in the car & lock using the infra red button.
2/. Within 30 seconds, switch ignition to position 2
3/. Watch LEDs to see if they go out, if not, go back to action 1 & start
again.Keep trying until it works, as I have tried up to 6 times before it takes.
4/. Once LEDs out, remove key, get out & lock car using infra red button & wait
at least 60 seconds before unlocking car, getting back in & starting engine.

Try these sequences with your old key before buying a new one, as I have also managed to re-sequenced my old key using the above.

The Mercedes mechanic I spoke to said when this happens, its a 70% chance of being the key, 25% chance of being the mirror receiver and 5% chance of being something more serious.

Despite my earlier reservations, the re-sequencing of the ignition code (key to ECU) is via the car, although initial 'master' programming is done at the MB factory. The Scorpion alarm & central locking is a separate system from the MB immobiliser, although they share the RVM LEDs as a driver warning/notification. The Scorpion system is linked to the PSE which operates the central locking so that it operates via the remote infra red.
I tried changing the various relays, K40, overvoltage, etc, to no avail. One thing the security system is very sensitive to seems to be battery voltage. Make sure your battery is in good condition & fully charged when doing all the above, as low voltage seems to screw up the programming/sequencing/general starting abilities.

Good luck
Garry