Viano/Vito (W639) Electric sliding doors - My fix

MinionBob

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This is a post that I hope can help others as fixing electric sliding doors can be a bit of a black art....

Problem: Viano would not lock electric sliding rear doors or the boot. Dashboard error saying LHS door unlocked. Problem was intermittent (and would 'fix' itself with no intervention) but had become worse over the last month to the point where it was pretty much constant.

Fix: New door lock (~£220).

Background/my Findings: There are quite a few parts to the electric sliding doors: Door & pillar contacts, door lock and the electric winding mechanism. Subsequently, diagnosis, at least at a DIY level is awkward as all I can get out of my Icarsoft is that the door is unlocked.

To be clear, in the following, when I talk about locking I don't mean the button going down as is the case when you lock the door via the keyfob; closed might be a better way of describing it but the dash uses the word 'lock' so i'm going to use this nomenclature. Lock basically means detecting that the door is fully and correctly closed.

Door and Pillar contacts were replaced (~£60), mainly as this is a cheap and easy job. No improvement.

Next I turned my attention to the door lock that is located in the rear of the sliding door. Upon removal, the electronic part can be removed from the mechanical part of the lock quite easily. The electronic part comprises a microswitch with a box of sealed electronic gubbins. The gubbins seem to house a solenoid with the flyleads from the microswitch going into the box housing the gubbins, all of which is sealed. The solenoid is the part that physically 'locks' the door for you and (I think) this locking is then detected by the microswitch.

I suspected the microswitch to be faulty as this appears to be the actual part that detects the locked status of the door. It made a nice click, and when tested was consistently working (closed circuit for door open and therefore open circuit for door locked). As a secondary test I put the door lock and electronics back into the door, refitted, but left the microswitch hanging so I could manually activate it ; no change; door would always be detected as door unlocked.

This really left me with three options; wire break somewhere, faulty lock or faulty electric motor. The electric motor is £1k ! so I ruled this out due to cost. I was doubtful about a wire break as the problem would fix itself without any intervention, suggesting that wire continuity is not being changed as would be the case if, say, the vehicle was moved or door opened. This left the lock. Replaced and it fixed the problem.

My instinct is that as the microswitch feeds into the sealed box of electronic gubbins housing a solenoid, the solenoid and switch must communicate with one another. Somehow either the solenoid does not fully or properly actuate, making the vehicle think that the door is unlocked and/or it does not correctly see the status of the microswitch.

The moral of the story is don't rely on the microswitch for diagnosis; there is more to it than that! Phew!
 
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MinionBob

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Sorry, forgot to mention when writing the above.

If you need to replace the door-opening roller arms (x3 per side, top middle, bottom) then I believe the top and bottom ones are generic across the vito/viano range and are the same whether electric opening or not - easily found on ebay or the like.

The middle roller used with electric doors is however specific to the electric door model; a new roller arm form Merc is about £150. I have found however that Autodoc.co.uk sells them under the 'Trucktec' brand, about £30 each. Left and right part numbers for the middle roller arms (whole assembly) is 02.53.288 left and 02.53.289 right.

HTH
 
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MinionBob

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Just an update. About 6 weeks after fixing the passenger side, the driver side door became faulty too, and was fixed in the same way via a new door lock. I replaced the door contacts first to see if that did anything, and it didn't.

Symptoms were similar to the passenger side - door would physically lock fine but upon driving away I would get the 'door unlocked' error on the dash and car would then refuse to lock on the keyfob. Sometimes the 'door unlocked' error would disappear for a few days through no human intervention, only to reappear for no apparent reason.

Only slight difference was that this time the 'door unlocked' error when it was 'active' would consistently disappear after approx 5 mins of driving, and then reappear when the door was opened.

All very odd.
 

N70ALX

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Just an update. About 6 weeks after fixing the passenger side, the driver side door became faulty too, and was fixed in the same way via a new door lock. I replaced the door contacts first to see if that did anything, and it didn't.

Symptoms were similar to the passenger side - door would physically lock fine but upon driving away I would get the 'door unlocked' error on the dash and car would then refuse to lock on the keyfob. Sometimes the 'door unlocked' error would disappear for a few days through no human intervention, only to reappear for no apparent reason.

Only slight difference was that this time the 'door unlocked' error when it was 'active' would consistently disappear after approx 5 mins of driving, and then reappear when the door was opened.

All very odd.
Hi, so glad to see a potential solution! We've had this diagnosed incorrectly as so many things over the last few years and had basically given up. Hopefully this will fix it!

Do you know what the part numbers are for the locks? Just wondering if the lock is the same on electric doors as sliding or not. And was it a big job to replace the lock? We're fairly competent amateurs...
 


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