W202 Flip Key Fob - How it works?

[lukejr]

Hi,

The flip key that came with the early W202 models (pre 1997) with one large button for locking and unlocking. Can someone run through how the key lock/unlocks and disables the immobilizer.

My understanding is that infra-red unlocks the car, via receiver in internal rearview mirror, where is the receiver located on the mirror.

How is the immobilizer disabled, is it done automatically when the doors are unlocked. Or does the ignition talk with the key when engine starts.

Can the immobilizer engage when traveling, by accident or fault?

Thanks in advance.

 

[lukejr]

Doing some digging online and according to a forum the lock/unlock module also disables the immobiliser, is this correct?

Just trying to figure how the system works so I can better diagnoise a problem with alternative flashing red/green lights on rear view mirror.

 

[aziz]

you probably need a new battery...because it happened to me recently and did not let me start the car..
also, if you can disconnect the immobilizer permanently if you go to some local electrical guys and they won't charge you more than £20.
http://www.mbclub.co.uk/forums/news/73728-my-w202-magazine.html#post818713

 

[KillerHERTZ]

I can better diagnoise a problem with alternative flashing red/green lights on rear view mirror.

I take it you have tried the 1st soliution of changing the batteries?

 

[lukejr]

Yes, I have tried changing batteries didn't solve problem. Also disconnected the car battery for a week and that didn't work. Tried second key too and re-sync again and that didn't work either. The key fob locks and unlock all the doors and boot, my rear view mirror has 4 lights on it, and all are working. Flashing green on unlock and red on lock, and then flashing alternativley when turn key to position 2 in ignition. My drivers side door doesn't have a key hole, it two has two little lights that flash red and green.

Local garages don't seem too interested, too much work for them (what recession?), the local Merc dealer has earmarked £1,000+ to fix, although haven't looked at the car, that was his best guess.

At the moment I'm considering what to do myself, Haynes manual doesn't refer to anything.

Car is a 1995 Mercedes C-Class C200 Diesel 1997cc W202, registered in August 1995.

Thanks for reply and help.

 

[Baron_Samedi]

As Aziz mentions, have you replaced the main battery?

Alarms do work in a flaky manner if the battery voltage is marginal.

 

[lukejr]

Getting a new one this weekend. Will post outcome.

 

[lukejr]

Forgot to say the AA called out and hooked up a battery booster to my car battery would that have simulated the same affect as a new battery, as that didn't work.

Looks like the AA in Ireland is not as good as the UK, he checked the battery and then offered to tow it home.

 

[andy27168]

If the lights are flashing together the immobilser is malfunctioning, lights flashing alternatly the fob batteries are flat, don,t think cos the fob operates the locking that they are ok.
The immobiliser on your car should be incorporated into the alarm system and is operated by the remote, it sends two signals one for the locking, and one for the alarm/immobiliser.
Together with the previous thread on this issue, and the one on the "other" forum i think you have gleamed about as much info that is available on these older systems, which is more than you would generally get from MB, not because they won,t tell you, its because they don,t honestly know.
I had the same problem, my cars immobiliser was stuck on, called the AA out and he had it running inside of 10 minutes, the info is in their technical publications, and gives exact details on how to bypass it.
If you look carefully at "all" the threads on this forum and the "other" forum you have posted on, and provided it is the same system as fitted to my C230K there has been enough info been given to bypass this immobiliser, but i can,t tell you outright on the forum as i have been warned previously about this and would run the risk of the security of other vehicles.

 

[lukejr]

Thanks again Andy, I'm doing the rounds on the Mercedes forums around the web, I'd say some are fed up with me asking questions at this stage. But the support and feedback has been great.

This weekend I'm going to spend a lot of time with my car and see if I can get it going by looking though all the forums, and gathering all the information and see if I can bypass it or get it going somehow.

 

[andy27168]

Once you have enough posts PM me and i,ll point you in the right direction, but do not buy a new battery yet, as this system is not as susceptable to low voltage as the later vehicles, just for clarification your engine does still crank does,nt it

 

[lukejr]

Yeap engine cranks alright. Could get it going for a second and cuts out.

I will bring battery in and charge over night to make sure it's topped up. I'd say it's run down with all the attempts and messing over the past two weeks.

Thanks for help.

 

[lukejr]

Andy, got a lend of a battery charger, took the car battery in today to charge, hooked up to charger for 6 hours, only slight increase in energy, so I'm guessing the battery is dead.

Battery was working fine in the car (little light and all on it that showed good battery, no longer showing) would all the trying to start and lock/unlock discharge the battery so much that it would die to the point it could not be re-charged.

If it doesn't gain strength by tomorrow evening I will go to Halfords and buy a new one. Will update.

 

[WLeg]

Is it an original key ? - to me (no expert) it sounds like the transponder in the key is not turning off the immobiliser.

 

[lukejr]

New car battery installed (€125 from Halfords) I was hopefully it would work, but no same problem with alternative flashing RVM lights.

I have tried both keys and re-synced with car and neither are working, turning off the immobiliser. My car only has an immobiliser, no alarm. Its the C-Class model with no drivers door key lock, just two LED instead. Both key fobs lock and unlock the car, but won't deactive the immobiliser.

I have a number of someone who may be able to help so he's to get back to me.

 

[lukejr]

Update on progress. New battery is dead today, car is draining it when locked, so have taken out to re-charge.

 

[hank_marvinson]

did you have any joy with this in the end?

 

[skinsta]

key fob

hi i had a problem with my key fob sounds like the problem your getting i pointed the key fob at the mirror pressed once then inserted the key turned till dashbourd lights came on waited for 30 seconds then took the key out and aimed it at the mirror and it was fine all the lights on mirror whent back to normal good luck

 

[lukejr]

Update on this, the ECU is dead in my C200. That's what caused all the problems, from doing some Google searches this is common in old C200. Car is at garage, hopefully to get a replacement ECU second hand, as they are very expensive if bought new.

 

[alexander patie]

good luck with that. have you tried bridging the retro immobiliser if it has one? you would have the small silver stickers in your windows if fitted.