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D3 - Axles, Brakes, Suspension and Steering Brakes, Springs, shocks, steering racks, steering columns, suspension arms, wheel hubs etc. |
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Thread Tools | Display Modes |
#21
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Quote:
The fact that there are only 2 'signal' wires would lead me to suspect that it's just a simple voltage/resistance measurement, anything more sophisticated would require a power connection too. While it's possible to send power and data over the same wire, I think it's rare to see that in automotive applications.
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Mark ------------------------------------------------------ 2002 FE S8 Ebony Black Pearl ------------------------------------------------------ ------------------------------------------------------ Cars Owned: The Tesla Era: 2020 Model S Performance Ludicrous+ (present) (Black, with all black premium interior and carbon fibre décor, 21" sonic carbon twin turbine wheels and FSD capability) The Audi Era: '97 A8 4.2 (Ming Blue) --> '96 A8 4.2 QS (Dark Green) --> '02 FE S8 (present) The Citroen Era: '84 BX 1.6 RS --> '89 BX 1.9 DTR Turbo --> '94 XM 2.0L Turbo --> '96 XM 2.0L Turbo Exclusive --> '00 Xantia Activa 2.0L Turbo The Banger Era: '76 1.2L Lada VAZ-2101 (Ruski Fiat 124) --> '80 1.7L Morris Ital HL, finished in Ermine White and Rust Last edited by moltuae; 10th July 2019 at 12:35 PM. |
#22
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That other symbol is for a transistor. Probably part of the control mechanism for end of movement in some way?
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2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions, ski hatch retrofit; extended leather. Aftermarket DVB-T, reversing camera and full XCarlink (Bluetooth etc.). 2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior. Polestar performance "optimisation". (A much rarer model than a D2 S8 by the way!) Oh, and a brand new engine at just under 30,000 miles on the factory one! Finally: gone, but not forgotten..... 1998 D2 PF S8. AgateGrey/Platinum. Every option (I think) except electric rear seats, tiptronic steering wheel, ski hatch, towbar & dimming door mirrors. e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course. (internal dimming mirror added later) 1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon, Auto-dim mirror, Leather, Trip computer, Cruise control, OEM Ford SatNav with CD changer. And before that a lot of Rover 800s, a few oddities, a lovely Triumph Dolomite 1850HL with Overdrive and way back in my schooldays an Austin Seven aka Mini 850! |
#23
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I'm sure this was discussed previously, possibly on another forum, but I know I had similar thoughts when I had a D3 (5 years ago)....
From memory, the A8 had a hall sensor in the motor, that the passat does not. The motor is driven by a big transistor in the control unit (one per side) that had a tendency to burn out (or end up with a dry joint). On my car, I replaced one caliper (refurb from ECP) which was gummed up, a month or so later the other failed with the same issue so that got swapped also, but I couldn't get the fault to clear which was resolved by buying a brand new control unit - total cost at the time was ~£700.... if you want to use the passat motor, you may also need to look at the passat control unit, but that then leads to questions about broader integration, so was in my view at the time more hassle than it was worth. |
#24
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I think the transistor symbol is generally used these days to symbolise any type of electronic device/circuit rather than a single bipolar transistor, like it used to do (back in the days of single transistor ignition coil amplifiers, for example). The J540 ECU in the diagram has the same transistor symbol but no doubt contains numerous components and several integrated circuits.
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Mark ------------------------------------------------------ 2002 FE S8 Ebony Black Pearl ------------------------------------------------------ ------------------------------------------------------ Cars Owned: The Tesla Era: 2020 Model S Performance Ludicrous+ (present) (Black, with all black premium interior and carbon fibre décor, 21" sonic carbon twin turbine wheels and FSD capability) The Audi Era: '97 A8 4.2 (Ming Blue) --> '96 A8 4.2 QS (Dark Green) --> '02 FE S8 (present) The Citroen Era: '84 BX 1.6 RS --> '89 BX 1.9 DTR Turbo --> '94 XM 2.0L Turbo --> '96 XM 2.0L Turbo Exclusive --> '00 Xantia Activa 2.0L Turbo The Banger Era: '76 1.2L Lada VAZ-2101 (Ruski Fiat 124) --> '80 1.7L Morris Ital HL, finished in Ermine White and Rust |
#25
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I think the other wires are to do with determining pad thickness(wear).
When I stripped my calliper down to refurbish, I didn't see any other way that the car can determine pad thickness other than how far the motor mechanism moves in relation to the pad thickness that you are supposed to program in via vcds on installing the new pads.
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2006 A8 d3 4.2tdi sport stoke-on-trent. Last edited by ivanhoe; 10th July 2019 at 03:56 PM. |
#26
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The two thin wires are to count the revolutions of the motor and so calculate the change in pad thickness (wear) there is a hall sensor in the motor housing and these wires connect to that, it gives a small 'blip' signal when a magnet passes by. (A bit like ABS wheel speed sensor I presume).
As it was not very reliable, they went back to wear sensors in the pads on other models. There is a thought that the A6 EPB module is the same except for ignoring this wear input, therefore may be more reliable and you can just rely on your eyes for the pad wear. |
#27
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Hi Snapdragon
Does that mean then that it could be entirely possible to still use such a motor and simply hack the connector such that the additional two wires are not used? If so, then like you suggested, the pad wear could be left to just eyes only?
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Current: 2007 Audi A8 3.0 TDI SE Quattro - |
#28
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Someone was going to try it but if they did I missed the results - not aware of anyone trying it - so it is just a theory.
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#29
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It was definitely discussed here previously on the forum as a possible solution, and may have been paulrstaylor as he mentioned above.
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2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts My DIY jobs - Replaced alarm horn, Replaced Coolant Temp sensor, Updated RNS-D firmware, Installed Reversing Camera and Digital TV, Dashcam Installation, Retrofitted Rear Blinds, Auto-Dimming Rear View Mirror, Chrome Boot Struts Sold! 2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights My DIY jobs - Fan Jet Windscreen Washers, Retrofitted Electric Side Blinds |
#30
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Sounds like it would be quite straightforward to make an emulator (powered by the motor wires), generating the required sensing signal while the motor runs. Might take a bit of research and testing though.
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Mark ------------------------------------------------------ 2002 FE S8 Ebony Black Pearl ------------------------------------------------------ ------------------------------------------------------ Cars Owned: The Tesla Era: 2020 Model S Performance Ludicrous+ (present) (Black, with all black premium interior and carbon fibre décor, 21" sonic carbon twin turbine wheels and FSD capability) The Audi Era: '97 A8 4.2 (Ming Blue) --> '96 A8 4.2 QS (Dark Green) --> '02 FE S8 (present) The Citroen Era: '84 BX 1.6 RS --> '89 BX 1.9 DTR Turbo --> '94 XM 2.0L Turbo --> '96 XM 2.0L Turbo Exclusive --> '00 Xantia Activa 2.0L Turbo The Banger Era: '76 1.2L Lada VAZ-2101 (Ruski Fiat 124) --> '80 1.7L Morris Ital HL, finished in Ermine White and Rust |
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