W202 Key Fob Mystery

Jason C

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Hello,

I have a 1998 W202 and I have a mysterious problem with my 2 key fobs. (three button variety).

Ok, so one fob locks, unlocks and opens boot but doesn't turn in the ignition. Whereas the other one locks, opens the boot and turns the ignition but doesn't unlock the doors.

So at the moment I'm carrying both sets of keys with me which defeats the object of having a spare.

Any ideas?
 

John Laidlaw

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Feel free to shoot me down, but starting with the obvious- has this happened recently or since you've had the car? Have you changed batteries, and if so what quality? (I.e. Not pound shop specials which las almost a day sometimes )
 
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Jason C

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Thanks for your replies. One fob has Panasonic batteries and the other ones, no logo. It's been like this for a while, but getting fed up with taking 2 keys around with me. I've tried swapping the batteries over which doesn't make a difference so I figured it can't be a battery issue.

Thanks for the links, I will give it a go and let you know.

Cheers
Jason
 

Alex Green

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Well,

I tried all the methods described in the links to re-code my keys and no success. I'm not massively bothered about having to use the flat keys but it's now a bit of a mission to find out what is going on.

The only thing I didn't try was cleaning up the circuit board of the remote, as I could not fathom how to get the damn thing out of the key fob.

Jason C, any success with yours?

Alex
 
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Jason C

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I have tried resetting it using the instructions, didn't make a difference. I could only try it with one of the keys as the other one doesn't turn in the ignition.

My next plan us to get some compressed air and use it to clean the contacts. Have you tried doing that?
 

Alex Green

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I sprayed IPA into the key fob and used my can of air duster to blow it out until dry. No effect.

Wanted to get the circuit board out to have a look at the IR emitters but it's not coming out of the fob without a fight and not sure I want to get into that. Checked with my phone camera and the fob does emit IR light so pretty sure it's not that anyway.

Both my key fobs will not turn the key to any position so the button pressing technique whilst on position 2 is a no go.

Cleaned the ignition barrel sensor with IPA on a cotton bud and removed a fair bit of gunk that may have been blocking the IR from the fob but doesn't seem to have helped.

It seems like whatever 'handshake' the car needs to see from the fobs before allowing movement on the ignition barrel is not happening or not registering. Not found enough info yet to determine what that handshake is and why the fobs will lock/unlock the car but not start the ignition.

The search continues.

Alex
 

Alex Green

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Just found a YouTube on how to get the key apart.

 

David Richardson

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This should resolve your problem.

Almost certainly going to be the small coil at the thin end of the circuit board, total repair cost at remotekeyfobs is likely to be £59.95 (mine was & taken from my post last week)


Time line

My key was received by repairer at 11.22 on Mon 8th May & there were various prompt messages & report of their findings the next day (Tues 9th May) Payment was made and the fob was returned by signed for mail & received here in Plymouth this morning 11th May.

Nickesh at remotekeyfobs in Blaby is certainly an honest repairer who is worthy of praise & recommendation

http://www.ebay.co.uk/itm/390729135149?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

David
 
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Jason C

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Thanks David, I'll message him explaining the problem. Hopefully he'll be able to fix it.
 

Alex Green

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Also messaged him.

Thanks David

Sent from my SM-G930F using Tapatalk
 

Alex Green

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might be this problem which i documented many moons ago

https://www.niallbrady.com/mycar/c220/fixkey.html
Thanks for the info.

Pretty sure my fobs are still able to transmit IR as I've used my phone to view it when I press the button and it picks up the infra red pulses.

Still going to take one of the fobs apart and see what it looks like though.

Alex

Sent from my SM-G930F using Tapatalk
 
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Jason C

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Thanks anyweb, could be a project for the weekend.
 

Alex Green

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Mystery solved for one of my key fobs. The little coil that talks to the immobiliser has come off the pcb.

The fob still locks/unlocks the car once back together so I'm gonna quit whilst I'm ahead and get this one sent off for fixing and not mess with the other one until I've got a good'un in my hands.

20170724_161520.jpg

20170724_161556.jpg

Coil should fit neatly in that space on the pcb above it and connect to the copper wire just poking out of the little bit of black plastic.

Alex
 
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Jason C

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That will be it! I haven't had the time to dismantle mine, but I'm sure it is something similar to what has occurred in yours. I also plan to send mine off.
 

Submariner1

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Sending one of mine to Nickesh This week .
This fell off
IMG_3947.JPG
IMG_4294.JPG

I found corrosion on the other fob.
Used WD40 Contact Cleaner ... WOW
Miracle sh*t, totally transformed it. Sparkly clean board, and bright shiny gold tracks ... ace stuff
.. and hell the fob works too ;)
 

Alex Green

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Key received back from Nick and everything works as it should.

Quick turnaround and excellent result.

Sent from my SM-G930F using Tapatalk
 
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Jason C

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Fantastic! I'm on holiday for a couple of weeks so will send it to him when I get back.

Great news!
 

David Richardson

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Glad that you're happy with Nickesh's work Peter. As at the beginning of the post, I couldn't recommend him highly enough

Dave
 


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