Well after 2 days locked in the Workshop, phones switched off .........................
Steering Wheel buttons all working 99.9 % faultlessly after a lot of messin', at one point it was all gonna get chucked in the bin
I have Volume + and - , Call Answer / Hang Up, Track /Radio \/ and /\ and then the 2 extreme left "Menu Buttons" are programmed that upper one Switches to Radio, lower one Switches to Media SD Card ................
The 2 "Menu Buttons" are redundant on the R170 as the Dash Cluster does not have all the Menus etc that the "more modern" Benzes like W220 R171 and W203 etc have, so I made good use of them 2 as well
The hassles I had is due to where I put the Resistors in the Switch Plugs, it is very tight when fitted on the Airbag Assy, the wires have to bend at almost 90 degrees as soon as they come out of the Plug, this fractured a couple of Resistors on the first attempt
Second go, both Switches were fine, but somehow, despite me modifying the SWC 1 Pin that came out of the Horn Button Module thingy, it was somehow corrupting the resistances, they worked fine on multimeter but the H/U stubbornly refused to recognise a button press
I ended up wiring both Switches direct to the SWC1 wire from Clockspring and bingo they all programmed in a treat
Steering Wheel is all assembled for the final time now, and it's all working fine
The only thing left to do is modify the "spare shifter" which arrived yesterday, and then fit that and plug it in to the 2 "Paddle Wires" that are waiting patiently coiled up behind the Shifter that is in the Car
It's not as tidy as I'd have liked with wiring inside the Steering Wheel, but I only see that when I remove the Air Bag, and it's all connected nicely and won't chafe etc, so that'll do for now................
I've proved it works and can be done !!
I have a complete spare Airbag with Buttons, one day, I will build the Mk2 Switch / Horn Button Module set to get it all as neat as I would like .................
The trick, from what I've learned in all this will be to ditch the little MB Circuit Board in Horn Button Module, and run all the Wiring etc inside it's Plastic Casing, and use a smaller custom made PCB for Horn Buttons and Clocksprings Plug in pins !!
Then I'll also use Micro Resistors inside the Switches themselves, and just hard wire to the Pins where the Clockspring Plugs in, which is what I've done with the Paddles
When one of our youngsters comes up, or when I work out how to do a U Tube Video on my Android Phone, I'll do a Video, but for now you will have to work it out from pictures ...........
The first couple show the (untidy) wiring behind Airbag, but hell it all works, that's the real result
I know I can get it tidier though, using the OEM Plugs like I have on the Paddles, (remember this is OEM for a W203 / R171) and not R170 which had none of this malarky
The Brown wire coiled up down by Steering Wheel Bolt is actually SWC 2 to the Android H/U, I'm not using this right now, both Left and Right Switches are wired to White SWC 1 .............
There is a very slight glitch .................
I will probably try the Left Switch on SWC 2 channel as I think 8 buttons on SWC 1 is too much for one channel
On a very odd occasion, the H/U mixes up the SD Media (lower Menu) button for the "Track / Radio Station Down \/ button", it has happened twice now after many many switch off and re boot fiddle with buttons cycles
Other than that everything works flawlessly. I think just having 4 buttons (Right set) on SWC 1, and 4 Buttons (Left set) on SWC 2 will make that go away ................. 15 minutes at weekend to try that.
The resistances on these 2 Buttons are nowhere near each other in ohms value by the way, I'm certain it is to do with the H/U getting mixed up, it copes fine with just 6 Buttons programmed onto SWC 1 Channel