# Replacing Battery



## ErosM (May 31, 2017)

Greetings! New to the forum. I have a 2008 TT roadster...battery needs replacing. Audi indy mechanic says they need to program the battery to the car for an extra labor charge. Is this true? I read on this forum that you simply start the car and leave it running while you replace the battery and all is well. I don't want to have to pay someone to fix all my components and fobs if I can replace the battery myself...everything is soooo darn expensive!

Thoughts?

Thanks!


----------



## brittan (May 18, 2007)

There is some information on disconnecting and reconnecting the battery in one of the 'How-To' posts in the Knowledge Base at the top of the Mk2 page.

Programming the car for a new battery is simply entering the capacity (Amp/hours) of the new battery and is only necessary if the car is fitted with the battery monitor unit. If fitted the monitor unit is part of the negative terminal and has a separate round electrical plug point.

The workshop manual says that the procedure is to connect a battery charger to the remote battery terminals under the bonnet for the duration of the change process. DO NOT simply start the car and leave it running while you replace the battery - all will not be well.

Don't forget to reconnect the gas discharge hose to the new battery.


----------



## Hoggy (May 8, 2002)

ErosM said:


> I read on this forum that you simply start the car and leave it running while you replace the battery and all is well. Thoughts?
> Thanks!


Hi, Definately don't do this ^^^^^^
Hoggy.


----------



## ashfinlayson (Oct 26, 2013)

Replaced the battery on my mk2 coupe a few months ago, plug and play no coding needed


----------



## andyk17 (Aug 30, 2016)

Hi,

Do you mean the battery in the car or the key fob, will the car run without a battery?

Andy


----------



## ErosM (May 31, 2017)

Thanks all! I guess I can't believe everything I read! Checked the battery, did not see the monitoring system you mentioned. If I follow the procedure outlined, I should be able to do it myself.

Thanks! [smiley=book2.gif]


----------



## ReTTro fit (Nov 9, 2014)

No monitoring on a mk2

Sent from my iPhone using Tapatalk


----------



## ashfinlayson (Oct 26, 2013)

literally a case of unscrew the old one and pop the new one in mate, I didn't even need to enter a code for the radio


----------



## SwissJetPilot (Apr 27, 2014)

My battery has finally given up the ghost, and rather suddenly! I'm wondering if I could have screwed up something with the VCDS while looking at the various menus.

I did manage to screw up the lights. Under [55-Headlight Range] I gave myself a _Headlights Not Adjusted, 005 No or incorrect Basic setting / Adaption - MIL ON_ by changing the drop down menu. The DIS suddenly showed a yellow headlight and to be honest, I'm not actually sure how I manged to screw that up. However I believe I corrected the problem as I no longer have any fault codes in [55-Headlight Range] and the yellow headlight symbol has gone.

The car did hesitate slightly to start on Sunday before I hooked up the VCDS, and I ran it around the block without any drama. This evening, after hooking up the VCDS and going through all the screens just to see what was available, the DIS was displaying TPMS in yellow which I had not seen before but otherwise there were no other issues. It wasn't until I tried to start the car that the battery was obviously dead.

I bought this car back in 2013 and have not changed the battery since owning it, nor do I know how old it was when I got the car. So maybe it's just time for a new battery and playing with the VCDS was coincidental...??

I currently have the following faults which I didn't have yesterday, and I am hoping they are directly attributed to a dead battery. Even worse, my DIS menu has reverted back to displaying in German! Scheisse!

03-ABS Brakes -- Status: Malfunction 0010
08-Auto HVAC -- Status: Malfunction 0010
14-Susp. Elect. -- Status: Malfunction 0010
44-Steering Assist -- Status: Malfunction 0010
4C-Tire Pressure II -- Status: Malfunction 0010

.


----------



## TT-driver (Sep 14, 2010)

MIL on = your orange check engine light is on.

Most other faults are due to loss of electricity. After installing a new battery and driving some sharp corners, some of these faults (and perhaps all) will disappear.

I changed my language settings to German on purpose! It's a German car after all. (OK built in Hungary, but by German parents)


----------



## SwissJetPilot (Apr 27, 2014)

@ TT Driver - So do you think the dead battery was just coincidental? And not due to something I did with the VCDS? Do you think putting a trickle charger on it would be worth it or is it just time for a new battery?


----------



## rajanm1 (Feb 1, 2014)

SwissJetPilot said:


> @ TT Driver - So do you think the dead battery was just coincidental? And not due to something I did with the VCDS? Do you think putting a trickle charger on it would be worth it or is it just time for a new battery?


I found if the engine wasn't running then vcds kills the battery so it might still be ok?

Might be worth a read as well: 
viewtopic.php?f=19&t=1390889&start=30


----------



## TT-driver (Sep 14, 2010)

SwissJetPilot said:


> @ TT Driver - So do you think the dead battery was just coincidental? And not due to something I did with the VCDS? Do you think putting a trickle charger on it would be worth it or is it just time for a new battery?


Didn't you have a low battery warning the other day?
Question is: how long have you been exploring VCDS with ignition on and how much capacity was still left in the battery? The older a battery gets, the less capacity remains. Since it's now dead, better get a new one. You don't want to encounter a dead battery again when it's winter time.

If would post a picture of the battery, then we might be able to tell if it is still the factory one.


----------



## SwissJetPilot (Apr 27, 2014)

@ TT Driver - Yes, that's correct. With the ignition off, the [26-Auto Roof] was showing around 11.4 or so. But looking "END" comment at the end of both tests, I'm very suspect of the VCDS itself, at least when running scans without the engine on.

This is from yesterday's test "End----(Elapsed Time: 01:27, VBatt start/end: 11.8V/11.6V. VIgn 11.6V)"
This is from this evening test "End----(Elapsed Time: 01:30, VBatt start/end: 9.8V/9.2V. VIgn 9.2V)"

Dumb question - and a day late - but should the car be running when scanning? It looks to me like the VCDS is really draining the battery big time given I started with 11.8V yesterday and I'm now down to 9.2V this evening.  Either that or something was left on after the test?

FYI - Here's a summary of scan and error codes from this evening - Thankfully I got the roof sorted!  I'll post a picture of the batter tomorrow evening.

*Address 01*: Engine. No fault code found.
*Address 02*: Auto Trans. No fault code found.
*Address 03*: ABS Brakes
2 Faults Found:
01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30 
00668 - Supply Voltage Terminal 30 ; 002 - Lower Limit Exceeded
*Address 08*: Auto HVAC
2 Faults Found:
01206 - Signal for Duration of Ignition Off Time - 008 - Implausible Signal
00446 - Function Limitation due to Under-Voltage 000 - - Voltage: 10.00 V
*Address 09*: Cent. Elect.
10 Faults Found:
03099 - Rear Right Turn Signal Lamps (M8), Voltage: 11.75 V
00987 - Lamp for Brake Light; Left (M9), Voltage: 12.10 V
00988 - Lamp for Brake Light; Right (M10) , Voltage: 12.10 V
00984 - Left Tail Light (M4), Voltage: 13.40 V
00985 - Right Tail Light (M2), Voltage: 12.10 V
01519 - Bulb for Back-Up Lights; Right (M17), Voltage: 11.85 V
02745 - Bulb for Daytime Running Light; Left, Voltage: 11.90 V
02746 - Bulb for Daytime Running Light; Right , Voltage: 11.90 V
03098 - Rear Left Turn Signal Lamp (M6), Voltage: 11.75 V
03099 - Rear Right Turn Signal Lamps (M8), Voltage: 11.75 V
*Address 14*: Susp. Elect.
1 Fault Found:
01316 - ABS Control Module, Voltage: 4.95 V
*Address 15*: Airbags
1 Fault Found:
01578 - Airbag Deactivation Warning Lamp; Passenger Side (K145
*Address 16*: Steering wheel. No fault code found.
*Address 17*: Instruments. No fault code found.
*Address 19*: CAN Gateway
2 Faults Found:
01300 - Control Module for Navigation with CD-Rom (J401). 004 - No Signal/Communication - Intermittent
01304 - Radio. 004 - No Signal/Communication - Intermittent.
*Address 22*: AWD. No fault code found.
*Address 25*: Immobilizer. No fault code found.
*Address 26*: Auto Roof. No fault code found.
*Address 37*: Navigation
3 Faults Found:
00446 - Function Limitation due to Under-Voltage. 002 - Lower Limit Exceeded. Voltage: 10.10 V
00862 - Antenna for GPS Navigation (R50/R52) ***non-OEM "stubby" antenna replaced by owner.***
00857 - CD Changer Unit (R41) . 004 - No Signal/Communication - Intermittent
*Address 42*: Door Elect, Driver.No fault code found.
*Address 44*: Steering Assist
1 Fault Found:
00778 - Steering Angle Sensor (G85) 000 - - 
*Address 46*: Central Conv.
1 Fault Found:
00955 - Key 1. 005 - No or Incorrect Basic Setting / Adaptation - Intermittent
*Address 47*: Sound System
1 Fault Found:
01304 - Radio. 004 - No Signal/Communication - Intermittent
*Address 4C*: Tire Pressure II
2 Faults Found:
01316 - ABS Control Module. 013 - Check DTC Memory - MIL ON. Voltage: 10.50 V
00778 - Steering Angle Sensor (G85). 013 - Check DTC Memory - MIL ON. Voltage: 9.70 V
*Address 52*: Door Elect, Pass. No fault code found.
*Address 55*: Headlight Range. No fault code found.
*Address 56*: Radio
3 Faults Found:
00446 - Function Limitation due to Under-Voltage. 002 - Lower Limit Exceeded. Voltage: 10.10 V
00862 - Antenna for GPS Navigation (R50/R52). 011 - Open Circuit - Intermittent
00857 - CD Changer Unit (R41). 004 - No Signal/Communication - Intermittent
*Address 77*: Telephone
1 Fault Found:
01304 - Radio. 004 - No Signal/Communication - Intermittent


----------



## Hoggy (May 8, 2002)

Hi, Try recharging but @11.8 v I would think the battery is knackered & requires replacing.
Hoggy.


----------



## TT-driver (Sep 14, 2010)

VCDS doesn't draw much current. It runs on a laptop and all that is happening is some data going backwards and forwards. Much like the old fashioned modem. The car's computers are all powered up too, in order to be able to communicate. Those computers do draw a substantial current. Cars like the A8 often have 2 batteries in order to be able to play a bit with the car's electronics and still be able to start the engine.

"00446 - Function Limitation due to Under-Voltage 000 - - Voltage: 10.00 V"
means the car went into power save mode as the battery was running low.

I suspect that the car didn't go to sleep after yesterday's VCDS session. The tell tale sign is that the red triangle on the warning lights button stays lit. If that is the case, lots of electrical systems are still running and haven't gone in stand-by mode. Current draw can easily be 1 to 3A whereas in stand-by it should drop to around 30mA.


----------



## SwissJetPilot (Apr 27, 2014)

@ TT-Driver -

_"I suspect that the car didn't go to sleep after yesterday's VCDS session. The tell tale sign is that the red triangle on the warning lights button stays lit. If that is the case, lots of electrical systems are still running and haven't gone in stand-by mode. Current draw can easily be 1 to 3A whereas in stand-by it should drop to around 30mA."_

And how, exactly, does one ensure the car is "asleep" after a VCDS session? This is important since I plan on playing with my new toy quite often - well, as soon as the battery is back in shape! [smiley=bigcry.gif] I'll go out to the garage now and ensure it's all tucked in for a good nights rest!


----------



## rajanm1 (Feb 1, 2014)

I just start the engine when I want to play with VCDS


----------



## TT-driver (Sep 14, 2010)

SwissJetPilot said:


> And how, exactly, does one ensure the car is "asleep" after a VCDS session? T


I once found my TT didn't go to sleep. Funny enough my little OBD 'scangauge' was lit too. I just unlocked it, switched on ignition once more for a minute. Switched it off, locked the doors. Couple of minutes later the car went asleep: the red triangle was off.


----------



## SwissJetPilot (Apr 27, 2014)

Found this post related to the VCDS draining the battery and I experienced exactly the same issues...warning lights on, spoiler deployed, not enough voltage to do anything. :x

viewtopic.php?f=19&t=1193481&start=15

Unfortunately, this post did not have a good root cause analysis...what's causing this problem and how can it be prevented?

The evidence would indicate that scanning a vehicle without the engine running will drain the battery very quickly. Okay, so we only run a VCDS scan with the motor running. Not a problem. 

But the battery drain seems to be directly related to the VCDS scan keeping a module on, even after the scan is complete and the car has been shut down. 

Did you turn the ignition to just the first position, or did you actually start the car again after disconnecting the VCDS connector from the vehicle?


----------



## TT-driver (Sep 14, 2010)

Full ignition, second position just before starting.


----------



## SwissJetPilot (Apr 27, 2014)

Okay - I'll go connect the trickle charger and see if I can recover my battery. Thanks for the tip. I'll keep an eye on the Emergency Triangle too. Note to self..."it should be off".

If I find what you just described in the VCDS instruction manual, the lap top is getting a whack! [smiley=book2.gif]


----------



## TT-driver (Sep 14, 2010)

Your laptop is probably save


----------



## brittan (May 18, 2007)

Could this issue be caused by the order of connecting VCDS and starting the scans and then disconnecting?

I have a note glued to my laptop that says: power up laptop; connect cable; ignition on; start VCDS.

When I've finished I reverse the above and I've never had any issues with the car (Mk2 or Mk3) going to sleep afterwards.


----------



## SwissJetPilot (Apr 27, 2014)

It's quite possible I failed to start and end the sequence in the order you recommended. I'll make a note to do so in the future and also turn the engine on and off just to be sure everything goes to sleep as it should after testing. Thanks for that!


----------



## SwissJetPilot (Apr 27, 2014)

Checked the TT this morning and first sign that things were good was the emergency flasher switch was not illuminated! So I disconnected the trickle charger and she fired right up! Yay!

I still have a few error messages on the dash as noted below, so now that I know how to start and end a scan properly, I'll get them sorted out this evening. Included is a picture of the battery. Visually it looks okay so I'll see what the scan shows for actual voltage level. Fingers crossed.


----------



## brittan (May 18, 2007)

The yellow warning lights should go out once you've driven that car and the relevant controller gets some inputs.

And that's my charger!


----------



## SwissJetPilot (Apr 27, 2014)

@ Brittan - As you described, I fired her up, drove up the street and all the warning lights all went out on their own. Nice! I did run a scan and cleared the stored errors and verified the voltage was back up at 14.0V so it's all good to go!

Yeah, it's a really nice charger. Just wish it came in a hard plastic case, rather than a cheap tie-string bag.


----------



## TT-driver (Sep 14, 2010)

Glad the errors disappeared. I was kind of expecting that.  
That battery seems to be battery that was installed in the factory. 99% sure.


----------



## sweatystt (Jan 29, 2015)

brittan said:


> There is some information on disconnecting and reconnecting the battery in one of the 'How-To' posts in the Knowledge Base at the top of the Mk2 page.
> 
> Programming the car for a new battery is simply entering the capacity (Amp/hours) of the new battery and is only necessary if the car is fitted with the battery monitor unit. If fitted the monitor unit is part of the negative terminal and has a separate round electrical plug point.
> 
> ...


Connect the battery charger to the remote battery terminals under the bonnet? Need to charge my battery.....


----------



## brittan (May 18, 2007)

Yes you can charge the battery using the remote connections


----------

