Retro Fit Rain Sensor

[whitenemesis]

Just pulled the covers from my RLS and OCP

There is no cross-over in the wiring. Left to right is red-violet-brown on both connectors...

 

[hercules]

Is there possibe for the sensor to get damaged if the violet and brown blue where crossed over??

 

[whitenemesis]

I think the violet is data and the brown/blue is ground, so probably not.

Do you have a multi-meter? Perhaps you could check?

 

[hercules]

I think the violet is data and the brown/blue is ground, so probably not.

Do you have a multi-meter? Perhaps you could check?

Yes checked already there is 12v between rd-bu and bn-bu

 

[whitenemesis]

I would strongly suggest you contact Richard (comand.co.uk) for guidance on this. comand ltd aren't far from you.

IIRC when I connected mine initially I didn't swap pins 2 and 3 (as in your post#38, loom as supplied by MB) nothing went pop but didn't work either!

When Richard looked at it for me STAR reported the sensor as open circuit. When the wires were swapped (so sensor pin#2 = ocp pin#2 .... etc.) the wipers worked.

I was lucky that pins 2 & 3 were only data and ground!

But it does highlight an inconsistancy in the wiring info for the 203 against other models regarding this pin-out, please be careful!

 

[hercules]

It is done :bannana: :bannana: :bannana: :bannana:
Thank to Richard for making the final coding
He is the MAN

 

[whitenemesis]

Well done!

Did you need to change any wiring?

 

[hercules]

No ,I left the Wiring As you mentioned ( post 41) and not as per WIS

 

[miro]

I recently looked into this problem with a 2007 W203 (one of the last ever built) and sure enough it was one of those cut-down version light sensors which do not directly translate into into a rain sensor without a change of windscreen and some new wiring.

well this is what we did.

1) Harvested the plastic bracket from a broken windscreen which had a 2003-2007 rain sesnsor

2) Removed the light-only sensor bracket from the glass. Glued on the new bracket.

3) Installed the new wiring harness by changing the connector at the OCP end. The existing wiring ran into the main OCP power connector, the new position was independent (white plug).

The pins positions at the rain sensor end were moved according to the WIS diagram.

4) Rain sensor installed

5) Power down the OCP / then back up

6) Coding - DONE


The hard part was attaching the new bracket to the glass and the fiddly bit was making the existing wiring harness function as the combined rain sensor harness and the pin swaps at the rain sensor end.

It can be done this but it needs the correct connectors and someone to donate the bracket from an old windscreen.

 

[Smatt]

I recently looked into this problem with a 2007 W203 (one of the last ever built) and sure enough it was one of those cut-down version light sensors which do not directly translate into into a rain sensor without a change of windscreen and some new wiring.

well this is what we did.

1) Harvested the plastic bracket from a broken windscreen which had a 2003-2007 rain sesnsor

2) Removed the light-only sensor bracket from the glass. Glued on the new bracket.

3) Installed the new wiring harness by changing the connector at the OCP end. The existing wiring ran into the main OCP power connector, the new position was independent (white plug).

The pins positions at the rain sensor end were moved according to the WIS diagram.

4) Rain sensor installed

5) Power down the OCP / then back up

6) Coding - DONE


The hard part was attaching the new bracket to the glass and the fiddly bit was making the existing wiring harness function as the combined rain sensor harness and the pin swaps at the rain sensor end.

It can be done this but it needs the correct connectors and someone to donate the bracket from an old windscreen.

So, in summary, it's probably easier to just have the screen replaced (for £50 xs) with the new bracket, get a 2nd hand RLS & then get that coded.

 

[whitenemesis]

So, in summary, it's probably easier to just have the screen replaced (for £50 xs) with the new bracket, get a 2nd hand RLS & then get that coded.

In a word, Yes!

But then, where's the fun?

 

[miro]

So, in summary, it's probably easier to just have the screen replaced (for £50 xs) with the new bracket, get a 2nd hand RLS & then get that coded.

Not so confident myself that I would want a brand new car fitted with a new windscreen. It seems overly tedious to do so. The act of modifying the existing glass in place seems to me more "contained" as I require no external services to do so.

 

[miro]

In a word, Yes!

But then, where's the fun?

Owning a Mercedes is FUN ... owning a personalised, modified Mercedes is more fun.

 

[whitenemesis]

Owning a Mercedes is FUN ... owning a personalised, modified Mercedes is more fun.

Agreed 100%

 

[Smatt]

Not so confident myself that I would want a brand new car fitted with a new windscreen. It seems overly tedious to do so. The act of modifying the existing glass in place seems to me more "contained" as I require no external services to do so.

I understood that the frame needs to be bonded to the screen very accurately. If it is not done well, then there will be refractive errors & the rain sensor will not work predictably.
I prefer an oem bonded frame/screen (which is what I had fitted after a screen cracked) for the RLS.

 

[whitenemesis]

I understood that the frame needs to be bonded to the screen very accurately. If it is not done well, then there will be refractive errors & the rain sensor will not work predictably.
I prefer an oem bonded frame/screen (which is what I had fitted after a screen cracked) for the RLS.

It's no much the frame to hold the sensor that is critical, it's the extra lenses that are bonded to the screen for the rain sensor.

Not sure if the 2007 203 had these already there, just not used. Seems that is what miro is implying by saying "cut-down version" of the RLS?

Certainly on the earlier 203 there were no "extra" lenses already bonded to the screen. PLus the OCP wasn't expecting the newer RLS hence the fiddle with the loom & connectors

 

[miro]

It's no much the frame to hold the sensor that is critical, it's the extra lenses that are bonded to the screen for the rain sensor.

Not sure if the 2007 203 had these already there, just not used. Seems that is what miro is implying by saying "cut-down version" of the RLS?

Certainly on the earlier 203 there were no "extra" lenses already bonded to the screen. PLus the OCP wasn't expecting the newer RLS hence the fiddle with the loom & connectors

Yes I meant to say that 2007-2008 W203 had a cheaper windscreen mounted LIGHT ONLY SENSOR which had a different bracket to the rain sensor. For the sake of that plastic it comes to changing the glass or that bracket.

In the 2003-2006 W203 the sensors came in a different form factor where the rain upgrade version used the IDENTICAL bracket as the LIGHT ONLY version.

This whole dance around the tree is all about the plastic bracket and updating the wiring setup.

 

[miro]

I understood that the frame needs to be bonded to the screen very accurately. If it is not done well, then there will be refractive errors & the rain sensor will not work predictably.
I prefer an oem bonded frame/screen (which is what I had fitted after a screen cracked) for the RLS.

Some insurance companies insist on using a cheaper windscreen which costs about 80% less than the OEM version. Still a decent and proper windscreen though. The only difference is that the plastic bracket does not come with these less expensive glass screens. Thus the "transplant" is done often and properly.

The caveat is not distance (as that varies a little) which is why they have the calibration step. The real issue is not to have a HUGE gap and most importantly NO AIR bubbles. It is the air which alters the refractive index hugely. If you go from GLASS >>> GEL >>> PLASTIC >>>> SENSOR it performs mostly as one optical unit without dramatic changes in performance (bearing in mind that the air is also inside the sensor in front of the final pickup),

What we are detecting here is the relative reflective index of a window which is dry and one which is wet. The additional layer of water alters the calibration values and triggers a wiper action.

So long as the bracket is tight - it will perform correctly. The tolerances are there for fitment as required by experts. The diagnostic does a calibration in the dry state.


Stay tuned. I am looking at converting my 2000 W203 into a 2007 rain sensor using the W221 part number.

 

[malluboy77]

Hi

I am a newbie to the forum and can't PM you. I am about to have a new windscreen put in my 2004 W 203 Facelift version with the light sensor in the middle and I guess the bracket for the combined light/rain sensor. I have just arranged with the dealer to get me the part no's you had mentioned in post 37, ie the combined light rain sensor, the cable and the connector.

Can I guess that it is going to be a straight fit with the cables not needing any pin change? There is a Hella writing on my current light sensor if it helps.

Thanks
Joe

 

[prc]

Hi,
No the actual screan is different. The standard screan has 2 lenses bonded to it, the rain sensor version screen has 10.
The bracket for light sensor will be same size for both versions, but your missing the lenses for the rain sensor.