W203 key fob problems after flat battery

MBSpeedbird

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My wife’s 2003 C180 (W203) -classic auto saloon has developed a fault last night with the central locking. After the battery went flat (mostly used on short journeys - but has a new (3mths) Varta battery) the key fobs would not open the doors.

Used the mechanical key to open drivers door (alarm siren went off), opened the bonnet and disconnected the battery to stop the siren. Checked battery charge only 11.3 volts. Put car battery on trickle charge over night (13.4v) and checked the batteries in both fobs. OK

Reconnected the car battery and alarm siren sounded off. Tried pressing key fob to close/open car, still doesn't work. After 20 seconds siren goes off, but indicators flash. After a minute all is quite and peaceful !!

Tried to restore the factory setting by pressing lock/unlock buttons simultaneously for six seconds/until little battery led flashed twice. Still nothing, Tried again with only a few mm from the door handle. Still nothing.
Tried again, with only a few mm from the key ignition port, still nothing.
Locked it all up with mechanical key, and tried sequence again, still nothing.

Any idea’s to allow some part of “Father’s Day to be stress free and take away the worry of going into the clutches of a MB dealership who wants a blank cheque just to diagnose the fault before presenting you with a bill to repay the national debt!
In anticipation of a favorable result -many thanks to the M C members reading this thread
 
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MBSpeedbird

MBSpeedbird

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Yes - as before tried the same test with key in ignition, barrel will not rotate, appears not be making a connection, ie instruments speedo mileometer not lighting up.
 

Mark@RMK

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It's your EIS then.

One last check, flick the light switch on and off and it should wake the dash up (mileage display) Does it display the mileage or --------????

Mark
 
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MBSpeedbird

MBSpeedbird

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Hi Mark

Tried your test, yes speedo lights up and shows mileage. Now what do you think its still the EIS, and is there any way round it. Surely this can't be right - flat battery causing an EIS failure?
Appreciate the feedback - Thanks
 

ccp

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I had this sort of issue a couple of winters ago when my battery got very flat and I was jump started. The radio frequency portion of the key fobs wouldn't work at all but I could unlock the car (sometimes) using the infrared link in the drivers door handle or use the emergency key.

After some digging I concluded that the rear SAM was either "unhappy" or damaged. I disconnected the car battery (when in a good state of charge) for 30 minutes and then reconnected it making sure that there was some electrical load on the system (courtesy lights on and a door open, headlights set to come on but key NOT in the ignition) when the battery was reconnected. I reconnected the battery and it all sprang into life.

I realise your symptoms are a little different but It would probably be worth trying.
 
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MBSpeedbird

MBSpeedbird

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PROBLEM NOW SOLVED - THANKS MB owners forum

After posting my problem on mercedesclub.org.uk members forum Mark immediately spotted the problem from the symptoms and posted some quick checks to verify the diagnoses.
I spoke with him on the phone and texted to arranged for him to call. Within 48 hours he came at the time arranged and sorted out the problem in under an hour and replaced the faulty EIS (Engine Ignition System – which is a known fault)
The price quoted over the phone was the price paid which was less than a third of MB dealer quote and no need for new keys either.
Every thing is working fine now. A very big thank you to Mark (http://www.replacementmercedeskeys.co.uk) for his professional attitude, equipment and attention to detail. I would highly recommend him. He is a very good and fair person and you have nothing to lose but a lot to gain from his advice and expertise.
:grin:
 

lalastorm

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W203 Key Fob issue

I had an issue with the key fob, it all began when I had a flat battery.

Charged the battery and return into the vehicle but experienced problems with the key fob central locking which failed and I had to use the blade. I don't know how but the the central locking start working again a few days later, I initially put this down to the batteries in the fob so ordered replacement cells. The new batteries arrived and I replaced the old one's. All seemed fine but then a few weeks later the central locking failed again. I began trawling for solutions such as you mention pairing the fob with the vehicle again by holding the lock/unlock switches on the driver central console. Then I saw mention that fuses could be the problem so I checked fuses 21/22/31/32/57 and 65 all seemed fine. I then pulled all the fuses in the boot fuse panel and re-inserted them after which BINGO the central locking was back on again.

I think that a connection must have loosened as around the same time the central locking failed I also experienced problems with the radio reception FM/AM was distorted when it had previously been very clear.
 


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