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| D2 - Axles, Brakes, Suspension and Steering Brakes, Springs, shocks, steering racks, steering columns, suspension arms, wheel hubs etc. |
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#1
4th June 2015, 10:06 AM
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Explanation of brake pad wear warning light (and MOT)
Can anyone explain exactly how the brake pad wear system works on an FL D2?
Mine came on part way home from The Meet, but went off after an overnight park up at home. Then came on somewhat later. Visually all pads look OK with a fair bit (several mm) left though the front discs are badly scored and will need replacing. It seems to stay on once on but isn't on after an ignition cycle, presumably a "lock" somewhere that resets after an ignition off. Nothing showing on VCDS so I'm guessing this is simple circuits/relays or similar. After hearing various tales about dodgy wiring near the brakes or (worse) deeper in the car I decided to test it yesterday as I had a couple of 40-mile journeys to make. It stayed off through many miles of driving as long as I only braked gently and used the gears/engine to slow down most of the time. Corners, bumps and other movements had no effect, ONLY applying the brakes reasonably firmly. So how exactly does it work - e.g. wires embedded in the pad that are shorted by the disc? And is this an MOT fail or just advisory - assuming the brakes otherwise work OK. Mine is due fairly soon I think.
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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".  (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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! 
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#3
4th June 2015, 10:35 AM
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That diagram is it. A single wire that runs from the instrument cluster through both the front brake pads and back to an earth.
Any wiring fault, nick, loose connection, rubbing, fault pad etc anywhere in the circuit, and the light comes on. Its common to hardwire it to ground behind the instrument cluster to stop it false reporting if you have an issue other than worn pads...
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For parts enquiries and Forum User Administration please contact customer services directly, not me  - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones. The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff...... The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous..... The First 20 Audis: 2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey, 2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue, 2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue, 2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey, 2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6, The Second 20 Audis: 2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue, 2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black  , 2007 TT Roadster, 2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black, 2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi) 2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black Most Recent Audis: 2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8 Everything Else 1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
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#4
4th June 2015, 10:40 AM
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David, I wouldn't describe mine as erratic, it's probably just a wire in one of the pads which is just exposed so only making contact when braking firmly.
So, reading that, both sides need to be worn as they are in series? Any comment re MOT?
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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". (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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!
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#5
4th June 2015, 06:12 PM
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Quote:
It seems that pad wear warning lights are totally ignored by the MOT. Obviously the brakes do still have to work, which they definitely do. 
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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". (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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!
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#6
11th August 2015, 03:47 PM
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 Gone for MOT today, driven there by my friendly neighbourhood MOT tester. He texted me to say the pads REALLY ARE worn.  (and no, it's not a fail, or anything at all) The front discs need replacing, which I know, so it seems that their uneven surface has just cut through one of the pads at the wrong place. Still a reasonable amount of pad left over much of the surface, but it will all get done fairly soon.
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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". (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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!
Last edited by HPsauce; 11th August 2015 at 03:49 PM.
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#7
4th June 2015, 10:42 AM
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Basically, the cluster is constantly monitoring pin 17. Normally it should always be grounded, like on the picture. If cluster senses that there is no ground (at least for a split of second) you will get a warning light until you switch off the ignition again.
The disc eats into a wire and eventually breaks the connection of the pin 17 to the ground. Intermittent warning light with good break pads usually means oxidised contacts in the electrical connectors between the brake pads and harness of the car. See T4ad and T4ae on the picture. Remove the wheel, trace the cable from brake pad into the car. Find the 2 pin connector, disconnect it (you will need a flat screwdriver to unlatch it) and inspect contacts within the connector. If you see green or white oxidation, then remove it. Also, make female side of connector tighter by squeezing contacts. You'll need a needle-shape tool for that. I used the dentist tool that you can buy on eBay for this. Before assembling the connector back please put some conserving non-conductive grease there to prevent future oxidation. You will never have the problem again.
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I'd rather drive on left Last edited by notorious; 4th June 2015 at 10:44 AM.
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#8
4th June 2015, 10:53 AM
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OK, thanks, that makes more sense.
Given that it's ONLY applying the brakes that triggers the warning it suggests a poor contact close to the moving parts, i.e. the calipers, so first suspect is the local plug/wiring.
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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". (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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!
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#9
4th June 2015, 02:46 PM
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I started getting this warning just before setting off to the meet. If you or I are really unlucky a wire can break somewhere between the connectors and then its a real pain to find where it is broken underneath the insulation, or maybe if this is the case best to replace the whole wire. You can easily test which side with a continuity meter (pad side or car side when connector is unpluged).
I think someone on here has had to replace the car-side wire before.
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#10
4th June 2015, 03:09 PM
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Are the connector plugs accessible by turning the steering or does it need jacking up and the wheel taking off?
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions and extended leather. Ski hatch retrofit. Aftermarket reversing camera. DVB-T and XCarlink now removed as redundant. 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". (Even rarer than a D2 S8!) 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. Agate Grey/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. Added Auto-dim mirror, Leather seats, 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!
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