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Discussion in 'Electronics' started by Scorcher, Sep 27, 2008.
Can I replace this blank with a button?
If so, any ideas on a part number and or cost?
If the E is anything like the 203 those buttons come as a set. You can't buy them individually
I have a couple of blanks in mine but would have to get a complete new switch bank @ £164
Depends on what the problem is?
Are you concerned about the look of the switchpack - i.e. something looks to be 'missing'? Or do you have a purpose to which a switch could be put?
I've got the estate, so this blank is filled with a rear wash/wipe switch. You could always rig up some rear wash/wipe installation on your saloon...
I have a use for it - next major mod needs to be switchable
But as these switches are coded (I think so any way) it might be difficult to use one for another purpose?
It looks like a switch pack and options are available, but I wonder whether you could make the original work with some investigation.
I've heard of a dodge on VAG cars where just a peg needs cutting off a blank to make it work as a switch as the contacts are already there.
Ooooh... lets all play guess the mod
Hope he remembers to order the one for Right hand drive.
I'm afraid I'm equally pessimistic as whitenemesis that this would work. I believe the blind switch is for the rear window blind. All of these are anyway most likely read by a switch reading matrix by the control unit, then if the switch is pressed, the blind is operated through a CAN bus message to the rear SAM.
If the switch was built to directly power some individual target, it would be easier to access the switch poles. Now there must be a printed circuit board with buttons on a matrix and it may be impossible to cut the wires for this switch as that would cut the connection to the next switch. Some cutting and jump wires could make it, unless the circuit board is a multilayer board.
The switch would not handle high currents but you don't mention if your application would manage with a control signal only. If you are very lucky, it could even work but likely needs a lot of effort.
But if you build a CAN bus decoder and code the rear window blind existing on the car, you would get the switch info "easily" by tapping to the correct CAN bus.
The switches are probably built up as part of a matrix with different resistances feeding and returning different voltages to the controller.
As you say the power will pass through an individual switch, but there's no reason a flylead couln't be added to either the switch or the return line and onto a suitable low voltage control.
It needs investigation.
The switch pack is basically only on the car's CANbus, so all buttons send signals (that the SAMs pick up) and then turn on/off the appropriate outputs of the SAM etc
As Diesel Benz says, the switch is for the rear blind, which connects to the rear SAM.
So, why not use the Rear SAM outputs for the rear blind to control whatever needs controlling ? Rear SAM/ EIS may need telling there is an electric blind from star to enable them though.
The rear blind is controlled with 2 outputs (pin 1 and 2 on connector 25) a 7.5A fuse (Fuse 20) and ground - Outputs 1 and 2 feed a relay pair for the rear screen blind for up and down. (as the motor needs to be powered one way round or the other for up/down). The relay pair is probably in one single relay block and I dont know where exactly it is but its not in the SAM itself.
The rear screen blind wiring harness is A211 540 41 06 (about £38) and i'd start with that as it will have the correct connectors on it for the rear SAM and give you a useful 7.5Amp power feed since you dont want to rely on the SAM outputs providing much power.
Also, i would deconstruct the switch block to see whether the switch mechanism is there and the button only needs tweaking to make it into a button as suggested.
The switch pack ("upper control panel") at the front are probably different between LHD and RHD so be careful if ordering a replacement switch pack.
I just bought this on eBay.com to cannibalize
Think I'll get the basic wiring done by my mechanic to the switch provided, in a temporary location and then get a nice man in Woking to do the tricky bits
Please tell me what will the switch do?
I can't sleep until I know.
PS..............Note to self.........
Must buy some screen wipes (!)
It's a frosted finish
This has been investigated by a member on one of the american sites in some depth for a facelft W203, even getting a replacement switch specially injected & made with a choice of his own symbol on