Strange Intermittent Central Locking Problem

[steveoelliott]

Hi all,

I have a 2000 W208 CLK Convertible which has developed a strange fault with the central locking. It is however intermittent.

The fault manifests itself in 2 ways.

1) Boot won't open via central locking or switch in car
2) After locking the boot opens itself within a minute or so, then alarm goes off.

When these faults occur you can hear the pump running in the boot continuously. So far after many times locking / unlocking it seems to clear itself but obviously I am worried about using it in case I end up in a position where I lock it and the boot opens itself and I'm unaware.

As a side note, for some reason both the passenger and driver door unlock when you press the unlock button on the remote, normally you have to press it twice.

Any ideas what the fault may be???

 

[steveoelliott]

Any thoughts???

 

[rebelrider4711]

Pse pump

Hi, i had a similar problem with my 2004 W220 it turned out to be the pse pump, kept changing the fuse then i had to change the pse pump it cost me £800 to change after that all was ok, HTH...

 

[steveoelliott]

Hmm... Not good if it turns out to be that. Problem is I would want to be 100% sure it was this before changing, if you catch my drift.

How was yours diagnosed?

 

[Dec]

Regarding the passenger and driver door unlock, there is Selective Locking Mode
And
Global Locking Mode… see page 30 and 31, here… http://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/ownersmanual/2000_clk_cabriolet.pdf

Until you find out what the fault is with the Vacuum pump you can lock the boot with the metal blade key in position 2… see page 39 of above link… this will prevent the boot from opening when its not supposed to, however it wont stop the vacuum pump from running when its not supposed to.

Could the boot open button on the remote control be damaged in any way?

Dec

 

[steveoelliott]

Thanks... I resolved the passenger door opening thing.

I'm working on freeing my boot lock at the moment anyway.

Don't believe so and anyway on my car it doesn't open the boot, my remote doesn't have this option.

 

[steveoelliott]

Well, the issue with boot opening by itself after locking remains. Once in this state it won't even close when shutting and the pump keeps on running. Several lock / unlock cycles seem to cure it. Very strange...

 

[Dec]

When you lock the car, the alarm is armed, it would seem the vacuum pump is running when its not supposed to because of a short or dirty or wet connection at the vacuum pump, you will need to examine the vacuum pump electrical connection s closely and spray them with switch cleaner.
That pump has a lot of connectors judging by the number of connection plugs on the pump, see eBay… Mercedes Benz W202 W208 W210 Central Door Vacuum Pump C280 CLK320 CLK 430 E320 | eBay

Dec

 

[steveoelliott]

When the issue next occurs, I would look ti play with the connections to see if there are any shorts etc. There is no moisture though, dry as a bone.

I have had a Merc guy look at the problem and the diagnosis from his star shows the pump overruning and shutting off. He has checked for leaks and no problems.

I am looking at swapping my pump as 2nd hand ones seem quite reasonable. I'm guessing they have a brain inside too.

 

[Dec]

If you are into taking things apart then have a look at this thread here… http://www.mbclub.co.uk/forums/electronics/154571-s124-central-locking-pump-types.html ... there are 2 pages and some links to follow.

Above is not the same as your pump but your pump should have a similar means of adjusting the length of time that the pump runs for when locking and unlocking.

How long does the pump run for when you unlock?
How long does the pump run for when you lock?

Pictures of the inside of your pump would be useful if you decide open it up.

Dec
Edit, did you get the lock to work with the key blade?

 

[steveoelliott]

When the fault is not present the pump runs normally, just for 2 seconds on lock / unlock.

It runs on forever when the fault is present (by forever until the boot opens itself after locking), maybe a sticky relay or something? I suspect these pumps have relays inside.

I can lock / unlock with the blade after many times with WD40 and whilst locking the boot with the blade does indeed stop it opening when the fault is present, the pump makes a very unhealthy noise then as it tries to unlock the boot.

I think I am just going to buy a second hand pump on ebay for £55 and get my merc guy to program it with his star. At least I rule that out then. I must say the pump doesn't sound that great when it runs. However, it seems to be enough the run the locks and seats most of the time.

On the seat point... I do have another thread on here where I mention that my seats stop working if I play with the settings too much and then they lose all air. However, if I set them when I first get in and then leave them alone, all is well.

 

[Dec]

It doesn’t sound like the pump needs adjustment if it run for 2 seconds, could be a relay inside the pump as you suggest.

One thing that could cause this long running pump is a switch inside the lock, there is a guide in the link below, it would be worth while unplugging this switch to see if the fault goes away, while the switch is disconnected it won’t be possible to open the boot by pushing the lock key hole inwards, you will need to use the inside boot open switch OR the key blade in the lock to open the boot.

Switch Guide… http://www.mbclub.co.uk/forums/body...lectronic-boot-lock-w208-possibly-others.html

You can just unplug the switch, no need to remove it, Brown and Blue wire in below picture.

The sole purpose of this switch is to run the vacuum pump when the lock key hole is pressed inwards. Try this before you buy another pump.
Don’t know much about the seats, I thought that the engine vacuum played a part in that.

Do you have the Owners Manual for the car?

Dec

 

[steveoelliott]

Hmm... In my scenario the trigger can be a lock event or using the switch inside the car. The example above is just when operating the switch.

My issue is pretty sporadic and manifests itself in multiple ways. That's why I'm leaning towards the pump or some electrical problem.

Really appreciate your advice and words of wisdom Dec... Yes I do have an owners manual. The seats are operated by the rear pump. You can hear it when they pump up. I was told the air vents are engine controlled though.

 

[Dec]

My thinking is that as that switch is capable of running the pump when boot lock is pushed inwards, perhaps / maybe it’s stuck partially closed and any locking event from the remote or inside car switch is activating it by locking vibrations in the boot.

If you can get the same pump on eBay then that will be the best way forward, let us know what transpires.

Dec

 

[steveoelliott]

Well... Ever since stopping to use my contour seats, the issue has stopped (seemingly) Maybe there is something to do with using the contour seats that triggers my issue.

 

[Dec]

I think the contour seats are involved with vacuum pump you might be best to get it diagnosed with someone with STAR.

Dec

 

[steveoelliott]

They are indeed... And yes.

 

[spike60]

Pumps can be bought quite cheaply on Ebay though there are a load of slightly different part numbers on similar looking pumps. The one I bought doesn't seem to be enabled for contour seats so I swapped the filler lock and seat pipes over, the only downsides are fuel filler doesn't lock and the pump runs for about 8 sec when you lock/unlock.
My local indie wanted £72 try to enable the seats but didn't seem convinced that was the problem, as the car has 200k miles and the pump cost £12 I thought I'd give it a shot!
The pump runs when you push the button in the lock or pull the release in the centre console, could your problem be one of these controls?

 

[steveoelliott]

Since changing PSE pump, all issues resolved!

 

[L2e8]

I have a very similar issue, as the fob no longer works, and the interior button although had a live feed does no longer open the boot, all the doors and fuel cap work, which of the blue it brown should be live as I have tested these and they have no positive ?