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D2 - Transmission Gearboxes, diffs, drive shafts.

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Old 10th December 2017, 11:40 AM
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Default Brake switch cause limp mode?

So I picked this A8 up yesterday, it drove back and for some fortunate reason it didn’t hit limp mode for about 90 Miles, kickdown worked if a little lathargic, lock up was fine and didn’t seem to slip at all.

Now the fault codes are the g195 implausible signal 17105 and brake switch electrical malfunction 17087 these codes where cleared and return by the way.

The reason I wondered if it’s the brake switch as if I cycle ignition and drive straight off the box stays out of limp mode, but if I hold the brake pedal for any amount of time at standstill the box usually clunks into limp mode, I can brake whilst moving without issue just when it comes to a stop, I’ve tried google and on here but not a lot of info, anyone else came across anything similar? Just the fact the box behaves like normal whilst running is what is throwing me regarding the speed out put signal issue.

Just incase, the car is a PFL 4.2 4 speed

Thanks guys.
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Old 10th December 2017, 12:47 PM
HPsauce HPsauce is offline
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That sounds like 2 different problems. The G195 issue would more likely give limp mode.

And on a PF (non-DBW) D2 you get a brake switch fault anyway unless you dab the brakes before doing a scan. So that may be 100% spurious.
See: http://wiki.ross-tech.com/wiki/index...7/P0703/001795
Quote:
When found in Vehicles with Drive-by-Cable (DBC) the Brake Switch (F) is connected to the Transmission Control Module. On older Models this Code is stored automatically after Terminal 15/Ignition is switched ON. If the Brake Switch (F) is OK you can avoid this Fault Code by pressing the Brake Pedal after switching on the Ignition and prior to checking Fault Codes. The Code should automatically be cleared then.
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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.....
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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; 10th December 2017 at 12:52 PM.
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Old 10th December 2017, 01:38 PM
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Would it only cause limp mode when stationary? Pretty sure brake fault is present as cruise doesn’t work iirc, but I will double check
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Old 10th December 2017, 01:40 PM
HPsauce HPsauce is offline
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Turn on ignition and start car, check TCM codes, press brake firmly and check again.
Then go for a short drive and check again with engine still running.
That should help clarify things.

Cruise not working could be several things including a faulty stalk and faulty control module (it's a separate unit in the ECU box under the bonnet).
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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!
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Old 10th December 2017, 02:16 PM
HPsauce HPsauce is offline
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Quote:
Originally Posted by Burnzybubbles View Post
Pretty sure brake fault is present as cruise doesn’t work iirc, but I will double check
Remember the brake pedal switch actually has 2 circuits in it (definitely FL, presumably PF).

One circuit really only triggers the brake lights, the other informs the ECUs and they are ever so slightly set apart so that one changes just before the other as you apply the brakes.

You can check the operation with the relevant measuring blocks using VCDS, just can't recall which ones they are. (Used that to diagnose that mine was mis-adjusted and causing odd gearbox behaviour)
Edit: Engine measuring block 66, at least on FL. This is what I said nearly a year ago in another thread:
Quote:
Originally Posted by HPsauce View Post
Just tried that with VCDS. The switch was showing a value of 1000 when untouched.
A VERY LIGHT touch on the pedal (engine off) would change it to 1010 but the slightest bit more and it went to 1011.
That sequence could be reversed by lifting off very carefully.
__________________
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!

Last edited by HPsauce; 10th December 2017 at 02:29 PM.
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Old 10th December 2017, 02:42 PM
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Burnzybubbles Burnzybubbles is offline
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Thanks mate I’ll give it a go, PFL has the same type of brake switch with 4 pins.
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Old 11th December 2017, 03:49 PM
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Architex_mA8tey Architex_mA8tey is offline
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My D3 exhibited similar symptoms a couple of times in London and I replaced the brake switch as I had read similar stuff but do you ever get poor starting when warm on the car ie refuses to turn over? If yes as well then it could very well be your Crankshaft Position Sensor on the way out which is what failed on mine eventually and cured that issue at the same time
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