repairing broken W202 Key fob.

[topgunkc]

Thanks for the info ,Any chance of a photo/pointer of the bit/ area you are trying to tell me about.

 

[television]

All over the board there are holes where the track goes through to the other side of the board,,it is the plating that goes open circuit in the hole you can test each one with an ohmmeter or bleep meter,,it could be any one that is used

 

[c13tay]

The IR functions work on my 3 button w202 key but the RF function doesnt (see my previous post on this subject)

anyone know how to fix this issue

thanks


Chris

 

[television]

Without a spectrum analyzer it is not possible

 

[topgunkc]

Thankyou Television I will have a go at that.

 

[merlin-5]

Key fobs

Many thanks Anyweb. Add me to your long list of thankful readers. Found your post ref repairing the old keys last night and today attacked the non-working spare for my 1995 C180 auto C Class. Now fully functional-- again many thanks.

 

[m.dijkens]

Thanks!

Thanks for this amazing thread about repairing keyfob! It even worked for my W210! I have a W210 (1996) with exactly the same key. My key started to become unreliable, sometimes it worked and sometimes it did not - until it stopped completely. I took it apart and the little switch came off, with one little leg broken off. I bought a cheap soldering set, put some solder on all four points on the circuitboard, removed the broken off leg. Then, I carefully put some solder on the switch where the leg was broken off - and pushed in place, holding it with one finger. Then, carefully soldering the four contact points, the switch made contact and the light came on when pressing the switch. Put the key back together and tried it on the car. Nothing happened - until a little later when I tried again (after driving the car locally) - and the key responded! It works better than ever - very happy chappy! Thanks anyweb for sharing this thread and showing such detailed images. I just replaced the front door of my W210 which was a job in itself - and coincidentally the keyfob stopped working at the same time. It's all fixed again!!!

 

[SNST]

Visiting Scotland for work, decided to relax with a hill walk in the evening.
The car wouldn't open on the remote. Ran the car downhill into the nearby village, alarm sounding, left the car and found a house where the owner let me use the internet & I found this thread!
Borrowed a soldering iron, followed your guidance and I was mobile again.
Thanks team & the village of Pools o' Muckhart!

 

[banksy]

my problems not the switch

hello there, i've had trouble with my key fob before, i sent it to malcolm who kindly fixed it, it was working fine up until last week, the problem is, the keys immits an IR beam but only some times? i've taken the key apart several times and played about the the solder joints with my soldering iron and it seems to then work but only for a few minutes? its very strange, i was thinking of buying a replacment key from ebay, can these keys be reprogrammed? or even if anyone knows what parts inside the key needs changing i could have ago at that?

mercedes c200 1995, single button key fob

many thanks

Jordan

 

[Dec]

The key fobs on e bay can’t be programmed, the only use that the have is for spare parts such as the casing and buttons.

If you are happy that the batteries are in good condition then try cleaning the batteries, top and bottom and the upper and lower battery contacts with switch cleaner, this is just to eliminate the possibility of a poor battery connection. Be careful with the contacts as the are easily broken.

Dec

 

[darkhorse]

c 220 m reg

hi

Ive read most of the post and they are incredibly helpful. The problem I have is that my key fob shows the red light but still does not work the alrm.

Any suggestions

 

[darkhorse]

c 220 m reg

hi

Ive read most of the posts and they are incredibly helpful. The problem I have is that my key fob shows the red light when the button is pressed but still does not work the alrm.

Any suggestions

 

[Dec]

What do you mean “does not work the alrm” Can you describe more about what the problem is…does the car start, does it lock/unlock, are there any lights flashing?

Dec

 

[bpar1713]

A different key problem

I'm not sure if this is the right place to ask but can't find anywhere else to do it so, here goes:-
One of my 2000 S320's 2 keys won't open or close the car all the time. It works very occasionally but the other key's fine all the time.
Looking at various marks on the door open and boot open sections of the key it seems it may have been trodden, dropped a long way or had something dropped on it so I'm wondering:-
1...Can the other internal parts of the key be removed to see if there's any internal damage once the valet key and battery holder have been taken out and, if so, how?
2...Assuming it's not repairable, is there a way to get a good replacement or do I have to go to the dealer?

 

[television]

The fault on your key could be a poor battery contact or a through hole where the plating is going open circuit.
The circuit board can be removed to check by lifting the catch on the nylon retaining strip

 

[ibestriker]

Hi friends

This is a great post, just like what I am facing now.

But my problem is a bit different.

Since 2 days ago, suddenly my key fob can't unlock my w202 (c200 year 95) and the green light at the rear mirror also doesn't flash.

So I open the key fob and check the circuit, found out that the 2 legs of the swith are detached. I then resolder them carefully and when i finished, i tried to press key fob button and the red lamp on the key fob flash once.

But when I press the button and check through my digital camera, i can't see the infrared (blue in colour). That means the car key is not transmitting a signal to the receiver (on the rear mirror) ?

Which part of the electronic components on the fob that i need to replace so that the infrared is working and can transmit signal to the receiver?

Anyway, even though the infrared is not working, I just tried to resync the key fob with the receiver. This is what i did:

1. Press the key fob button while pointing to the receiver on the rear mirror. No response. (previously when the key is working, the green light used to flash once when i press the key fob button)
2. I put the key in the ignition and turn to position (2). Lights on the dashboard flash, the green and red light on the rear mirror flash alternately (green, red, green, red, green, red).
3. I take the key off the ignition and tried to point the key fob to the receiver and press the button once again - still no response (both green or red on the rear mirror don't flash).

What should i do now? Any expert mind to assist?

Thanks in advance.

Naz

 

[ibestriker]

If the IR LED doesn't flash though my digital camera, that means the IR LED has blown? Or it is something else blown which cause the IR LED not working?

I would like to replace the IR LED, anyone knows which wavelenght (rating) of the IR LED? Is it 780nm, 850nm, 880nm or 940 nm? Or any value can be used?

Really hope anyone can help, I cant use my car for several days now

 

[Dec]

That’s an unusual fault, uncommon enough to suggest that perhaps your soldering repair may have failed and need redoing.

Dec

 

[ibestriker]

That’s an unusual fault, uncommon enough to suggest that perhaps your soldering repair may have failed and need redoing.

Dec

I dont think my soldering repair has failed. I tested the switch with multimeter, it works fine.

The only mistake i can think of, after i soldered the micro switch, i connected a digital power supply with 12V to the Infrared LED legs to see whether it flashes. Do you think it blown the IR LED?

 

[Mark@RMK]

12v??

it only runs on 2x3v batteries....