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AUDI A8 3.0 TDi 2009 - Customer allowed battery to go flat #

Posted by Ian Waring on February 27, 2014, 5:03 pm

Year of Manufacture *: 2009

VEHICLE HISTORY:

Customer allowed battery go flat which then became faulty whilst he was away. Audi dealership replaced battery and recoded.

After 2-3 days handbrake warning light came up with fault signals.

I have found no power supply to O/S/R Calliper.

I removed Handbrake Module and carried out continuity tests from Calliper to Module which was okay. Repeated checks to side which is working and all okay. Requires new Module.

Have never recoded Module on this vehicle.

I have Autodiagnos which shows ECU recode but need to clarify what the procedure is.

I gather these Modules are prone to going faulty if Battery goes low - is this correct?

Cheers,
Ian

Re: AUDI A8 3L TDI / ECU RECODE

Posted by John Ritchie <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2638' width='330' height='300' border=0 style='border:none;'> on February 27, 2014, 7:00 pm, in reply to "AUDI A8 3L TDI / ECU RECODE"

Hi Ian,

I would be more inclined to go for a faulty motor on the calliper as the ecu switches off the power supply when it sees an open/short, you could switch motors from left to right to confirm

Regards
John

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Jon Morgan <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on February 27, 2014, 7:12 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"
Jon Morgan

Some useful info here.

Follow the instructions to the letter, or you may have issues getting any settings to stick.

http://wiki.ross-tech.com/wiki/index.php/Audi_A6_%284F%29_Parking_Brake#Coding

As John just posted, these turn off a defective circuit, so a lack of activity is not necessarily a defective EPB ECU.

Also take a full vehicle scan before starting the repair, when coding the EPB it is not uncommon for the ABS ECU coding to be reset to factory default.

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Ian Waring <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5344' width='330' height='300' border=0 style='border:none;'> on February 27, 2014, 11:24 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"

Thanks for your replies and the link.

If I am going to use the n/s Electric Calliper Motor for testing purposes on the o/s circuit, is the Electric Motor removable from the Calliper or do I have to remove the complete unit from the Braking Circuit?

If the entire Calliper has to be removed, can the test be carried out without the Calliper being in the Brake Circuit?

Is it a case of plug Motor into the o/s but not into the Hydraulic System?

If the plug to Motor is disconnected and power and ground is checked from plug when operating handbrake - because the plug is disconnected does the EPB switch off? Does it sense there is no circuit?

If working Motor is fitted into o/s faulty circuit and plug is reconnected, does EPB sense everything is correct and bring power source back online?

You help is very much appreciated.

Cheers
Ian

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Ian Waring <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5344' width='330' height='300' border=0 style='border:none;'> on February 27, 2014, 11:36 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"

Taken from link provided by Jon:

"On vehicles using a separate battery management control module, make sure the charger is connected properly. The proper procedure should be found in the repair manual. ## Attaching the charger directly to the positive and negative terminals of the battery is Not correct. The battery management module will not see the current flow and shut off power to other modules. This can cause damage to various control modules including the [53] - Parking Brake module".

Does the above affect my vehicle as if I need to use battery support, I do not want to cause any problems!

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Fiachra Purcell <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3006' width='330' height='300' border=0 style='border:none;'> on February 28, 2014, 9:45 am, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"
Fiachra Purcell

Hi Ian.
I have no experience with the A8 but I have lots with the 3C passat which should be similar.
I made up a loom that just plugs into the caliper and then extends across to the opposite connector.
That way you can leave the caliper where it is.
I would use a battery support unit if you have one. If you don't a good booster pack should suffice.
HTH
Fiachra.

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Glyn Morgan <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on February 28, 2014, 1:31 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"
Glyn Morgan

Hi Ian,

I have a 2008 A8 in at the moment, the battery is in the right hand side of the boot.

There is a warning saying to connect the earth lead of your charger to the raised earth stud and not the battery terminal.

Is yours the same ?

Regards Glyn

Re: AUDI A8 3L TDI / ECU RECODE

Posted by John Ritchie <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2638' width='330' height='300' border=0 style='border:none;'> on February 28, 2014, 8:02 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"
John Ritchie

Last one i did had a 4 wire multi plug , i think they use the other 2 for brake pad wear

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Ian Waring <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5344' width='330' height='300' border=0 style='border:none;'> on February 28, 2014, 8:12 pm, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"

Yes Glyn, mine is the same. I used the earth terminal on top post.

Cheers
Ian

Re: AUDI A8 3L TDI / ECU RECODE

Posted by sean savage <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5559' width='330' height='300' border=0 style='border:none;'> on March 1, 2014, 11:16 am, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"

I drive one of these on same year, totally off key but my battery went flat. fitted new bosch gel battery, 3 weeks later traction control light would randomly come on when it wanted, turned out if the battery goes flat and the steering wheel isnt straight the steering angle sensor must be recalibrated!! just incase you start getting traction light on in the near future. also done the os/r caliper on mine.

sean

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Ian Waring <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5344' width='330' height='300' border=0 style='border:none;'> on March 2, 2014, 12:19 am, in reply to "Re: AUDI A8 3L TDI / ECU RECODE"

Thanks Sean - good one to bear in mind for future.

Cheers,
Ian

Re: AUDI A8 3L TDI / ECU RECODE

Posted by Ian Waring <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5344' width='330' height='300' border=0 style='border:none;'> on March 2, 2014, 12:35 am, in reply to "AUDI A8 3L TDI / ECU RECODE"

All help so far very appreciated

Vehicle has left workshop but is coming back in on Thursday.

Am going to make up a loom as suggested.

However, I am still stuck with my part of my earlier question:

"If working Motor is fitted into o/s faulty circuit and plug is reconnected, does EPB sense everything is correct and bring power source back online?"

Also, is it possible to connect power and ground wire to Calliper with the plug disconnected and run Handbrake Motor this way?

If anybody with a little more knowledge than I have, has five minutes to spare (tall order!) and would be prepared to briefly chat over the phone on this problem - that would be welcome!

Cheers,
Ian

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