Anyone managed to repair an R171 Door Control Module?

[Gilbertd]

Ever since her indoors has had her SLK 280 (R171), the central locking on the passenger door hasn't worked and neither has the door mirror adjustment on that door (although it folds and unfolds automatically). A bit of digging and forum searching pointed me to the door control module having got wet and taking it out and opening it up confirmed that it had got corrosion inside where water had dribbled into it. One forum post I found reckoned simply cleaning the green bits up with contact cleaner and a toothbrush had got one working again so I tried that. No joy, just the same so I told her she'd have to live with it.

However, my temporary bodge on the noisy heater blower (R171 heater blower temporary (bodge?) fix | Interior) finally gave up so a new blower was required. I found one from a breaker and asked if he also had a LH door control module. He had so I bought that too. However, having fitted it, I found it was exactly the same. I took the RH module out and plugged it in on the LH door and although the Canbus address was wrong, the central locking worked and the mirror could be adjusted as long as I used the adjuster for the RH mirror to move the LH mirror. That confirmed that I had yet another module that had been dripped on. The supplier had stuck a warranty sticker on it so I couldn't open it up to see if it had corrosion in the same places but I suspect it did.

As a(nother) temporary fix, I've wired the door central locking motor to the glovebox locking motor so the door now locks and unlocks with the fob but not from the button on the dash (as that only locks and unlocks the doors not the glovebox). It also means that the automatic locking when driving doesn't lock the passenger door either. So it looks like the only options are to risk overloading the RH module by wiring the LH door lock in parallel with the RH door lock (which I'm a bit wary to do), buying a replacement module or finding someone that knows which component it is that fails when water drips inside them and replace it. Has anyone managed to trace the circuitry, identify what it is that fails and replace it?

 

[Dodipops]

What’s the part number of your module? I have some but I think they’re off c and e classes.

 

[Gilbertd]

It's got more interesting now I've done a bit more digging. The module on the car is an A1718207126 which is what I was supplied with only to find it was exactly the same. Turns out that the A1718207126 is for a car later than serial 177100 but the car is 175588 and should have an A1718200726 which doesn't supersede to the A1718207126. I suspect the original one got water damaged (really stupid design having it mounted directly under the end of a rubber seal and not waterproofed in any way) so someone replaced it with the later version only to find it didn't work so just left it. The breaker is checking to see if he has an earlier one to swap with. He was OK with me breaking the warranty seal to check for water damage inside and it is perfect.

I understand a version that is interchangeable with the one on the SLK is fitted to another model only the initial 171 in the part number will be different so I would assume Axxx8200726 is what I'm after.

 

[Dodipops]

Sorry didn’t have any that matched the part number

 

[Gilbertd]

So, an update. Breaker supplied an A1718200726 which arrived today so I've just finished fitting it. With the A1718207126 in there the mirror adjustment and central locking didn't work but everything else did. With the replacement, the mirror adjustment works, the central locking works (after I'd snipped and insulated the additional wire I fited to drive it from the glovebox lock), the electric window works but NOT from the switch on the drivers door. It works from the switch on the passenger door, it works using the double press on the roof switch, it drops and returns when the door is opened so is doing everything it should do except operate from the switch on the drivers door. iCarSoft shows no faults but it doesn't seem to be detecting the drivers door switch so I'm wondering now if it is simply a dodgy switch on the drivers door (although it was working before so it would be one hell of a coincidence). Anyone know if there is a setting anywhere in case it is a silly H&S setting for the US market?

In case anyone is interested, the breaker that was able to supply the parts is in Latvia and uses the eBay ID of hssalvage (although he tends to list most of his items on eBay Germany). Excellent guy to deal with, speaks good English too (although that wasn't a concern as my partner is from Latvia anyway) and specialises in Mercedes parts, including RHD ones.

 

[Gilbertd]

Had a thought about this. Although I now have the correct LH door control module fitted, if it has come from a LHD car then there would only have ever been the one switch. The one on the LH door which would have been the drivers door and not another switch on the other side. Presumably this is something that would need to be coded? It doesn't look like the iCarSoft can do it (but if it can, I'd be pleased to hear from anyone that can tell me how to do it), is this something that someone with Star would be able to do?