w208 water in footwell key won't turn alarm not staying on

[prestige lease]

Hi , I've got a problem with my 2002 Clk 200k, the doors don't open with fob, when manually open the alarm wont shut down and I can't turn the key in ignition to start it.

ive had a key made and its been to the dealers for three weeks but no luck.
Dealers want me to keep changing parts until its sorted!

I do remember I had a leak in passengers footwell couple of weeks prior which I had fixed but not sure if that has caused it. Now sending it to a specialist local WestYorkshire to see If he can do something.

keep u posted..

any ideas?

 

[Dec]

You could try disconnecting the alarm siren, the siren is known to become faulty at around 10 years of age and can cause all sorts of problems when the go bad. This might not be a cure but at least a possible cause is removed from the car.

You can unplug the siren… the siren also houses the alarm brain… when you unplug the siren, it might (should) go off because it has internal back up batteries so it could sound for hours and hours.
Alternately
Unbolt the alarm siren and THEN unplug it and put it somewhere where the noise wont be a nuisance… inside the fridge perhaps.

Because the alarm system is not being disarmed (because the car won’t unlock with the remote fob) any door that is opened will trigger the alarm, that is normal, when the alarm is armed, the role of the key blade in unlocking the door or boot is purely mechanical, for emergency entry, and is non electric, in other words it doesn’t operate the central locking or disable the alarm it just unlocks the drivers door or boot.

Dec

 

[prestige lease]

Thanks , so when I dissconect the alarm system does the immobiliser which I think is not letting the key turn in ignition be unarmed as well as the alarm?

My battery is totally knackered due to the alarm going off and its been stood for a couple months. Getting a new one after alarm system removed.

Could the PSE system in passengers side be damaged and showing these symptoms?
What does it stand for? Wjats

 

[Dec]

PSE, I think its Pneumatic System Equipment, not sure exactly, anyway it blows air to unlock the doors boot and fuel flap, it sucks air to lock.

If you have a flat battery then the car wont unlock, you need to recharge that battery or replace it.
If the alarm siren was faulty then remove it as soon as possible.

Removing or unplugging the alarm will have no effect on the car starting or locking/unlocking, the immobilizer is contained inside the remote key fob, in other words the key fob is the immobilizer, the key won’t work in the ignition because the car battery is flat/dead… the battery, if it’s been without power for several months, may not even take a charge and may need to be replaced.

Dec

 

[markmifsud]

Isn't the PSE near the fuel flap section, I am 99.99% sure mine is. Also, as your car has been dormant for so long, it could also have lost sync with the key. There is a section in the manual on how to re-sync it. I think 1st things to do are. disconnect the faulty siren (if it is faulty) then see if the battery can take a charge. Then retry and test what works and what doesnt.

 

[prestige lease]

Thanks will try and disconnect alarm. Let's hope it is the alarm.. With passenger floor getting wet I need to check for damaged wiring or someone mentioned on a post about a 20amp fuse? Any ideas of what I should be looking for down their?
if pse is near fuel flap then what am I looking for in passenger footwell?

 

[andy27168]

If you have a wet passenger side footwell you need to fix this leak and dry out thoroughly. The passenger footwell has a number of ECUs in the footwell fitted behind a steel plate. All the major ECUs are on this side of the car either on this plate or in the plastic box above under the bonnet.
The leak into the car will most likely be the heater box which runs along the front of the windscreen it has a couple of drains which block up and water fills the box up and it overflows into the heater over the heater fan motor it can take it out and its speed controller as well.

 

[Dec]

The area in the foot well must be dried out, there is foam underlay under the carpet, and this will hold a lot of water.

When the carpet is lifted/pulled back you will see a footrest, remove the 3 plastic nuts that secure the footrest, not sure what’s in there but every thing needs to be checked for water/damp and any component that might contain water.

See this thread here… http://www.mbclub.co.uk/forums/interior/123659-removing-sound-deadening-clk-w208.html

All fuses should be checked.

The vacuum pump (PSE) is located as per video below, not worth examining it at this stage as your problem, as it stands at the moment, seems to be a dead battery and an alleged faulty alarm siren so remove the siren and recharge (if it will take a charge) or replace the car battery.

Dec
[YOUTUBE HD]LTVN2nnp9Kk[/YOUTUBE HD]

 

[sjmaxwell]

I had the alarm system go bad on my W208 which would occasionally drain the main battery flat when trying to top up its backup battery. It would start normally same times and other times it would be completely flat and not turn over, sometimes in the same day! The problem was only found by the dealer when the electrician lent on the box and nearly burnt his hand as it was so hot!

 

[Giantvanman]

the electrician lent on the box and nearly burnt his hand as it was so hot!

That's years of experience for you.

 

[prestige lease]

Hey guys been working on it today, disconnected the alarm rather than removing it ( it didn't go off) used a different battery which is good. Still had the same symptoms except for the siren.
So I decided to go for the footwell, took the carpet out and all I can say is it was WET. took metal footrest out and I came accross the yellow relay plug and a big black box as seen in pic ( nice1 DEC) took the relay plug apart and seen signs of water damage on it.. I took plugs out of the unit itself, that looked fine to me. So I guess this is what's causing all the problems!





I replaced the plug for a black one which I had at home as a spare but it made no difference. Should I buy a yellow relay plug as in pic??
Finally checked all fuses and in all three places and they are all good.

Where shall I go from here?

 

[Dec]

Do the outside lights and hazard lights work, the should without the ignition being ON… just asking to make sure all wires are connected at battery.

Did the dealer knew about the water leak in the foot well?

You could open that relay by prying around the edges but replacing it would be better with one with the same pins and numbers like 86 85 30 and whatever the other numbers are 87/87a?

What’s the part number on the big box so as to check what it is?

There are some more fuses in the ECU box if you haven’t already been in there.

Dec

 

[prestige lease]

Lights work and hazards.

Didn't mention it to dealers because I thought it was key or ignition fault.

I'll checked part number for you.

ecu box in top left corner of engine bay?

 

[Dec]

It’s the one on the passenger side near the windscreen washer tank, 4 screws on big cover.

Picture… http://www.mbclub.co.uk/forums/members-gallery/65258-my-w208-clk-320-a.html

Also, in the back end of the fuse box, driver side, 6 screws to remove cover, there are 2 relays for the wipers, if the same as your other Yellow relay then you could borrow one to test that water damaged relay.

That Yellow relay, if it was upside-down may have filled with water.

Dec

 

[prestige lease]

Checked all fuses are good.

bought a similar relay but made no difference.

the part for number for the box in passengers side is Siemens 5WPZ 000 5 BB , A030 545 23 32 may be thats shot?

 

[Dec]

Its an automatic gearbox ECU… https://www.google.ie/search?q=Siem....microsoft:en-IE:IE-Address&tbm=isch&imgdii=_

Did it get wet, don’t know if a faulty gearbox ECU would stop the key from turning.

As you say, it would seem that the leak is the cause of the problem, had the dealer known about the leak then the might well have been able to diagnose what was wrong.
The alarm going off or it being faulty is just a separate fault.

Dec

 

[Howard]

A faulty EIS would cause the key not to turn ?

Electronic ignition switch.

You really need to get it on a star to find out what's what or this could get expensive.

It's not unheard of for the EIS to fail.

 

[prestige lease]

Will a star read a car with central locking not working and key not turning in ignition?

Gearbox unit wasn't wet + its in a waterproof case.

ok Monday looks like I'll be paying a visit to Mercedes specialist I've had a word with.. he said something about needing the fob to open the doors or he won't be able to check it???

 

[Dec]

In the right hands star is suppose to diagnose faults.
Presumedly he needs the metal key blade in order to open the driver’s door.
Was the failure of the key the immediate result of the water leak or was the leak and key failure separate incidents?

Dec

 

[prestige lease]

All problems started at the same time.