W203 Sports Coupe boot micro switch

[Armstrong]

Hi All,

I've been having trouble opening the boot on my W203 Sports Coupe for ages. Sometimes it opens sometimes not but always needs a really hard pull to open. I can open it using the red switch but that means going through the back seat. I was told it was a microswitch problem. What and how do I fix this? What part should I look for on Google?

Any help very gratefully received.

Thanks, Sam

 

[Mr Greedy]

I have had the same problem for four years since buying the car. Last night the boot has failed in the open position. The latch will not engage with the U-shaped bar. The latch is open, and rotating it to the closed position does not cause it to shut. I have purchased a second hand latch from ebay to see if this cures the problem. Part A2037400235 I believe. It is £180 from the dealers.

 

[Mr Greedy]

I had two problems with my boot lock.

(i) The lock mechanism itself was playing up. Bother with the internal latching mechanism that has two click positions to secure the locking 'claw' (black in colour), and the claw itself had a little damage on one of the edges, which might have prevented it from turning in the original plane as designed. It looks like either the boot has been slammed shut mighty hard at some point (usually the wife when I've dropped her off and I'm still sat in the car, who slams it so hard I'm nearly left with burst ear drums and broken suspension; separate rant, why do women have zero mechanical sympathy. It's as if she thinks if she can slam it as hard as humanly possibly, it will 'shut better'; rant over), and

(ii) the micro switch housing had about 0.1mm (100 microns) of play in the mounting bracket for the boot handle. This was sufficient to mean that unless the boot handle was lifted really firmly, the micro switch was not engaged. I saw a previous post about securing this with a small cable tie, but even the smallest of cable ties I had were to fat at about 2 or 3mm width. I ended up cutting the securing head off a perfectly fitting cable tie, which just slotted in the gap between the rear of the micro switch housing and the boot handle (you will see what I mean if you strip all the trim off and look closely at the arrangement. I then secured the cable tie head in place with some fine garden wire, wrapped around the full length of the bracket for the micro switch housing, and tightened by twisting the two ends of the wire together. This pulls the micro switch fully towards the brass activating level that is moved when you lift the boot handle.

I bought the newest looking replacement lock that was on ebay at the time for £50. Part No. A2037400135, which in this instance was reported as being from a W204 2009 car, rather than my 2004 W203 model. The result is that the boot opens and shuts like new. Amazing! It's the best it's ever been.

Below is no way a full guide to stripping all the boot hatch trim, but useful tips for the tricky bits that are not blatantly obvious when getting to this:

The two pieces of side trim on the boot hatch must be slid towards the centre of the car when removing. Trying to move them towards the rear of the car is likely to break the securing lugs.

To remove the two pieces of side trim mentioned above, the parcel shelf string connectors act as screws, securing the trim. These are pretty weak, and one crumbled when shown the screwdriver. I've removed it by gripping the remains of the stump with loose vice grips and a useful piece of bike tyre inner tube for additional grip. I will buy replacements from Merc.

To remove the largest piece of trim that gives access to the boot handle and the third brake light, first remove the access panel in the centre of the trim to access to two hidden torx screws (as well as also removing all the obviously visible torx screws). Removing the access panel was pretty tough, and I have left a small screwdriver mark in the panel where I was prising it out. Once all torx screws are removed, the trim is only secured by two plastic lugs. Pull down firmly on the trim and it should be freed. The lugs just push back in when reassembling.

Good luck.

 

[Armstrong]

Hi Mr Greedy,

Very belated huge thanks. Worked a treat.

Sam.

 

[John Laidlaw]

That’s a record....
Two years between posts and one is a thanks.....

 

[Ken_R]

That’s a record....
Two years between posts and one is a thanks.....

Why the rush?

 

[John Laidlaw]

Why the rush?

What I need to know (cos I’m sad) is whether he fixed it two years ago or just got round to doing it now...as you say “why the rush”