Confused with W124 IR central locking

300TDT

Senior Member
Joined
Apr 17, 2009
Messages
108
Reaction score
0
Location
Tintern
Your Mercedes
E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
My 'new' 96 E300D came with three IR remote control 'keys'. One works fine, operates the doors, arms and disarms the alarm, and starts the car. The other two had been sitting in a drawer for a while and had flat batteries. I put new batteries in the spare two and went through the procedure in the owners manual (point the key at the receiver and press the button - then stick the key in the ignition and turn it to 2nd position within 30 secs) but neither work.
I took both to bits (and have the blood on my fingers to prove it) in case the switch had come off/something unsoldered but both are fine. I've checked the IR beam using a digital camera and again both work fine (I should have done this first and saved some blood!). The metal keys will start the engine OK, it's just the electronics won't switch off the alarm/immobiliser.

I don't like not having a spare or I'm stuck with not being able to start the car if it's immoblised.

Any ideas please?
Edit/Delete Message
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
332
Age
86
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
If the other keys have never been tried,,were they the correct keys for the car,,they came with 2 from new,,if they ar sending a beam into a camera , then they are working re the locking part
 
OP
3

300TDT

Senior Member
Joined
Apr 17, 2009
Messages
108
Reaction score
0
Location
Tintern
Your Mercedes
E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
  • Thread Starter
  • Thread starter
  • #3
Any of the three keys will start the car, but only the one remote will operate the c/locking.
Despite new batteries and the IR beam present, the two that have not been used for a while will not 'sync'.

If I can't get at least one of these other 2 remote controls sorted out, then I think I'll try and immobilise the immobiliser and remove the alarm, so at least I can get in through the passenger door and start the car if I lose my one working IR key.

I can't see anyone pinching a 13 year old diesel somehow!
 

grober

Senior Member
Joined
May 15, 2002
Messages
2,945
Reaction score
26
Location
Scotland
Your Mercedes
W204 C200cdi estate
If you have a digital camera do this test-take a picture of --or simply view in the camera display screen the key IR sender while pressing the operate button. If its operating correctly you will "see" the Ir beam as a grey/white flashing before the red test led lights up. The CCD sensors are sensitive to IR as well as visible light.
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
332
Age
86
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
As grober above ,I have put up a picture to test the beam.

You could also insert the key in the ignition and press any button on the remote to see if this will sync them
 

Attachments

  • Picture 249.jpg
    Picture 249.jpg
    26.7 KB · Views: 78

grober

Senior Member
Joined
May 15, 2002
Messages
2,945
Reaction score
26
Location
Scotland
Your Mercedes
W204 C200cdi estate
You need to sync the keys to the car system.
My MB W124 handbook detailed a method involving the ignition switch only--IT DIDNT WORK!!
Another a method employs the passenger door lock on the coupe model but this should also work for the saloon and maybe the estate also?
This applies to the circa 95/96 models with the green/red LEDS in the drivers door lock position without the LEDS in the rearview mirror.
FIRST and important, best get new batteries for your remote. MERC seem to use 2 varta CR 2025 for the flip key type. Test the key is operating by pressing the button for a couple of seconds, a red light should show at the front of the unit after a slight delay If you have a digital camera and you view this indicator thro the camera LCD display you should see a white light instantly you press the button since the LCD will pickup the infra red signal.
NOW go to the passenger door and make sure the car is locked.

1.point the remote at the lock at a distance of about 12 inches. PRESS the remote for 5 seconds.
2.unlock the door by turning the key in the lock
3. wait 10 seconds then remove the key.
4.repeat 1. for 5 seconds.
5.lock the door with the key
wait 10 seconds and remove the key.

Your key should now be synchronised with the remote locking and lock/unlock the car.

Be deliberate in your actions. check which way to turn the key to lock unlock the car before starting. Take time between steps.
this worked for me
Other synchronising methods may work. I tried several before the one I detailed worked. best to try it several times with slight variations to the timing till it works. GOOD LUCK
 
Last edited:
OP
3

300TDT

Senior Member
Joined
Apr 17, 2009
Messages
108
Reaction score
0
Location
Tintern
Your Mercedes
E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
  • Thread Starter
  • Thread starter
  • #7
Thanks Graeme, yes I've done that using a digital camera, and both work OK. I don't know why they don't 'sync'.

BUT I don't understand this synchronisation process anyway - if by carrying out the 'syncing' the car knows what code the key wants to use (because I assume there is no feed back to the key) then how come more than one key will work anyway?

For instance if one of my IR transmitters wants to use a particular code, say, 'A178' and I tell the car that this is the number I want to use, how come I can ever use another transmitter which is bound to be on another code 'G654' or whatever? (without 'resyncing' to the 2nd key rendering the first inoperable.)
 
OP
3

300TDT

Senior Member
Joined
Apr 17, 2009
Messages
108
Reaction score
0
Location
Tintern
Your Mercedes
E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
  • Thread Starter
  • Thread starter
  • #9
Sorry Graeme my post crossed with yours.

Many thanks for your most recent I'll try that tomorrow.

Still don't understand how it works, but will be happy enough if I can get at least one more remote operating!
 
OP
3

300TDT

Senior Member
Joined
Apr 17, 2009
Messages
108
Reaction score
0
Location
Tintern
Your Mercedes
E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
  • Thread Starter
  • Thread starter
  • #10
Graeme. Success! - with remarkable ease.

I tried pointing the (not working) remote at the unlocked car both on the drivers side and on the tailgate, and nothing happened as before.

Now I simply locked the car with the key on the passenger side with a view to following your instructions, and, trotting round to the drivers side, I pointed the remote at the receiver and lo and behold it worked - instantly, and activates/ deactivates the alarm/immobiliser as well as the c/l.

Not sure why- but at least I now have a spare key, yippee!
 

grober

Senior Member
Joined
May 15, 2002
Messages
2,945
Reaction score
26
Location
Scotland
Your Mercedes
W204 C200cdi estate
success

Glad to hear it. How exactly this "synchronisation" process works in practice nobody seems to know. The method described in the owner's manual doesn't work for many people-don't really know why?? Many disappointed owners give up at this point but ad hoc methods like the one I detailed seem to work for many folks-thankfully.
 
Last edited:

benrocker

Member
Joined
Nov 10, 2010
Messages
10
Reaction score
0
Location
Cornwall
Your Mercedes
1995 280 24v Bus, 1985 230ce, 1971 Series 3 Landrover
You need to sync the keys to the car system.
My MB W124 handbook detailed a method involving the ignition switch only--IT DIDNT WORK!!
Another a method employs the passenger door lock on the coupe model but this should also work for the saloon and maybe the estate also?
This applies to the circa 95/96 models with the green/red LEDS in the drivers door lock position without the LEDS in the rearview mirror.
FIRST and important, best get new batteries for your remote. MERC seem to use 2 varta CR 2025 for the flip key type. Test the key is operating by pressing the button for a couple of seconds, a red light should show at the front of the unit after a slight delay If you have a digital camera and you view this indicator thro the camera LCD display you should see a white light instantly you press the button since the LCD will pickup the infra red signal.
NOW go to the passenger door and make sure the car is locked.

1.point the remote at the lock at a distance of about 12 inches. PRESS the remote for 5 seconds.
2.unlock the door by turning the key in the lock
3. wait 10 seconds then remove the key.
4.repeat 1. for 5 seconds.
5.lock the door with the key
wait 10 seconds and remove the key.

Your key should now be synchronised with the remote locking and lock/unlock the car.

Be deliberate in your actions. check which way to turn the key to lock unlock the car before starting. Take time between steps.
this worked for me
Other synchronising methods may work. I tried several before the one I detailed worked. best to try it several times with slight variations to the timing till it works. GOOD LUCK

Excellent, tried a few different methods this one worked first time on a 1996 W124 - I now have a new (second hand) fob sync'd with the locks -
 

bigshineybike

Member
Joined
May 3, 2008
Messages
18
Reaction score
1
Location
Surrey UK
Your Mercedes
C320CDI W203, E300D estate 1996 multivalve, VW 1.9 auto, Triumph T509, Montesa Cota 348
Did I read that right BENROCKER, you got a second hand key to work with your 1995/6 W124?
I found someone on ebay has what looks like the proper key for my car £20 for two. he has tested the IR led but cannot promise the keys will work with my car.
From what I can see there are lots of keys look the same but there is a 3 digit number screen printed in white onto the 'chip' inside the key.
since there seems to be a maximum of 999 numbers available and thousands of cars built there must be a level of interchangability?
Or is each transmitter and receiver actually paired up at the factory.
 

Naraic

Moderator
Joined
Mar 4, 2010
Messages
10,532
Reaction score
1,137
Your Mercedes
2005 CL500.
There is no interchangeability...each key is unique.
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
332
Age
86
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
As above and no secondhand key will work.
 

Tony 300D

Registered
Joined
Jun 27, 2019
Messages
1
Reaction score
0
Your Mercedes
1996 Mercedes E300TE DIESEL W124
New member here, hello all, just been lucky enough to buy a lovely low mileage '96 W124 300D (non turbo) TE which has the same green/red LEDs in the door lock and no mirror LEDs. Similar problems to above. C/locking pump has just been replaced with a working secondhand unit which worked for a couple of days on the fob, but not this morning. Immobiliser kicked in and wouldn't kick out. Thanks to the info on this thread I've managed to get one of the fobs going at least in terms of disabling the immobiliser, but the central locking isn't working. Both our fobs had new batteries yesterday, but using the digi camera test I see that one is still not working. The new pump is definitely working (quite noisy aren't they!?). Car is booked in for Tuesday to try and sort it out. Very tempted to get them to lob the immobiliser into the skip, it's the only thing I don't like on the car which I bought for its old-school simplicity.
 


The SL SHOP YOUR ONE STOP SHOP FOR ALL THINGS SL, SERVICE & RESTORE, SALES, HIRE & PARTS
Choose from a wide range of superbly prepared SL’s each with a 12 month guarantee. We can service, update, re-trim, restore and repaint your 107 SL.
Choose from a 6 or 8 cylinder car for the day, the weekend, a month or a year. Contact us for a wide range of parts. Tel: 0844 414 2116 or visit our website atwww.theSLshop.com
Top Bottom