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Discussion Starter #1
After Audi couldn't solve a slow starting problem on Q7, I had an independent garage take a look at it (Audi fitted a new battery).


The mechanic who I took the car to said the voltage at the battery while cranking drops to around 9.2 volts, with a 3 volt drop on ground.

He thinks the problem lies with the J644 Energy Management Control Unit. He said he he measured 30 Ohm impedance to ground.

He also said when he bypassed the earth connection to the J644, and connected it to the battery instead, starting was improved.

I have ETKA and have read the instructions for replacing J644, but can someone explain how to code the unit using VCDS once it's been replaced?

Thanks.
 

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Discussion Starter #3
Of course Nikolas, I didn't think of that!

Am I right in thinking there is no component protection on this module?

Thanks again.
 

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Discussion Starter #6
Linkback to a description of your issue here: http://audiforum.us/threads/higher-capacity-battery-than-original-specification.14620/

Did a replacement J644 module fix your slow-cranking issue?
The J644 module is on order and I should get it this week or early next week.

Are you experiencing the same problem?

I have been searching the web now for quite a few months looking for any similar problems and yesterday I found this:

http://forums.vwvortex.com/showthread.php?2020343-J367-Battery-Monitoring-Controller-Replacement-(Includes-RVU-TB-27-06-02)

Although it isn't the same car or even module, it does make interesting reading.
 

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Thanks for the link, interesting indeed!
Yes, I'm having similar issues starting my '07 TDI. Mine sometimes cranks for 10secs before finally firing up.

Seems that the battery amperage is the tell-tale sign, rather than voltage. I'll check the battery amperage before and after a trip.

Keen to hear if a replacement J644 solves your issue. Did you buy from a dealer or elsewhere?
 

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Discussion Starter #8
Mine was also cranking for around 8-10 seconds before firing, but that was with a non-OEM Bosch battery I had fitted by a non-Audi garage. The Audi dealer said the garage didn't code the replacement battery even, and that it couldn't be coded correctly due to it being non-OEM spec.

The dealer fitted the OEM battery, and while starting was improved for the first few days, the long starting time returned, but not as bad as it was. The video posted in the first post on this thread is how the car generally starts these days, however, this morning I used the auxiliary heater as it was a frosty morning. I started the car after running the auxiliary heater for around 10 minutes and it took around 6 seconds to start.

I bought a warranted used controller as I got it quite cheap, but really should have gone for a new one I think. I'm keen to see if the replacement solves the problem too, and I'll keep you informed on this thread.

Please let me know if you come across any new info too.
 

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I bought my '07 model as a CPO dealer used car at the end of June '11. As part of this, the dealer installed (hopefully?) an OEM replacement battery before delivery. They told me that they had coded the car to recognise the new battery.
Like yours, my slow cranking issue started about 2mths after receiving the car, and even then only intermittently.

I'll definitely keep you up-to-date if I come across any new info. I think I've got the right tools to check the battery amperage, and will try to do that this weekend.

What's the part number for the J644 please? Did you notice if there were different revisions of the controller, like in they mentioned in the Phaeton thread?

Cheers,
Tim
 

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Just stumbled across this thread with similar issues:
http://forums.audiworld.com/showthread.php?t=2691561

There's 3 different "solutions" in the thread.
1) Apparently there was a TSB for an MMI software update to the battery management system to better address component hibernation. Possibly, TSB 91-07-13: "Battery dead or low after returning to vehicle".
2) Ignition switch replacement. Part number 4F0-910-131-L
3) Battery Manager replacement. Part number 4LO-910-181

Tim
 

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Discussion Starter #11
I have a copy of TSB 91 07 13 (file attached). My problem seems to be different to the one described in this TSB (radio not shutting down after car parked up). If I leave the car for 2 weeks without driving, it starts just as it does as if it has not been driven for 1 day - the battery doesn't run down while parked.

Rather, the problem seems to be the same as that described in the Phaeton thread linked to above; the car seems to only maintain the charge level of the battery at 80%. Testing of the battery using a battery tester shows it's a good battery but in need of charging.

As far as I'm aware, there are two software versions of the J644 for the Q7. The hardware version is 4L0 915 181, and the two software versions are 4L0 910 181, and 4L0 910 181A.

I think the software version 4L0 910 181A was introduced partway through 2007 when it was realised there was the problem described in TSB 91 07 13. If you have the earlier version of the software (4L0 910 181) then it can be updated using MMI upgrade software (3 pack of CDs which are available from Audi dealers for les than £4). If your Q7's VIN range is upto 4L 7D063347, then you are likely to have the earlier software version, and so it would be worth getting your MMI software updated to see if that resolves your problem.

My Q7 is above this VIN range, and VCDS confirms the software version as being the later one 4Lo 910 181A.

I updated the software on My Q7 using the 3 CDs just in case the software on the J644 software was corrupt, but this didn't solve the problem.
 

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the 3 cds updates only the mmi components (control head, tv, cd, radio, amp, tel, etc.) on the MOST bus and has nothing to do with any other controller on the can bus.
The can bus controllers like the energy manager can be updated only with the VAS diagnose system with online connection to the Geko server in Germany or as part of a SVM (Software Version Management) campaign. For this you need the SVM code and the latest Audi Flashing CD.
The energy manager software version is a 3 digit number.
 

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Discussion Starter #13
Thanks for the clarification Neo. Is there any way of checking the software version in VCDS?

I changed the J644 module for a used one form Media Car Tec, but the problem still remains.

The intake manifold problem that is common to the 3.0TDI is developing too, and I'm getting ABS and suspension errors also.

All this in the first year after the 3 year warranty expired.

I think it's time to fill the petrol can and buy a box of matches.
 

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Discussion Starter #15
Hey Zak .. did you ever get to the bottom of this.. did you get a new module ? is your problem fixed ?
I wish I could say yes, but unfortunately, after around a year, the problem is still there. I changed the J644 module and the problem was still there. I disconnected the J644 module, gave the battery a full charge, and the problem is still there:


The Audi Dealer has been unable to find the problem. It seems they are only able to resolve a problem if the car is showing a fault code. After first replacing the fuel filter housing, which they said was broken, they thought the problem was fixed (it was starting a little better because they had charged the battery on a trickle charger while they were working on it). After a few days the car took longer and longer to start each day.

Then they replaced the battery - this did go some way in improving the starting, but it still takes longer to start than it should, as can be seen in the videos.

The Audi Dealer then said they would contact me once they have located a Q7 with the same engine code so they can "try changing some parts over" to see if they can find the problem. Is this they type of 'diagnostics' to be expected from Audi?? I've been waiting 7 months now for them to locate a car with the same engine within the UK Audi network - I have chased them and had the response "we are still looking". I've been too busy to pay them a visit, but that's the next step.
 

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Is this they type of 'diagnostics' to be expected from Audi??
Sadly yes it is. The cars are no so complex that the vast majority of dealer technicians, even Master Technicians, can only fault find by doing either what the diagnostics tell them do or by random component swapping.
 

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Have they checked the earthing point located by the battery? But then again if they changed the Energy Manager, then they must have changed the whole cable connected to the negative pole of the battery, which on the other end is bolted to the chassie just beside the battery.

Or the cable from the positive pole; is it correctly mounted?

I was also thinking about the alternator... Maybe it does not charge the battery correctly, which renders into a useless battery after a while.

Did you know, that once the battery has been discharged so badly the car wont start, it will then only have half the original capacity. Discharge it again, and it will have half the capacity, from that half... and so on... So pretty quickly a 100Ah battery will have only 25Ah on only 2 discharges. Finally it cannot take any charge and needs replacement.

So the question is: With a NEW fresh fully charged battery, does it take this long time to start the car ANYWAY?
 

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Here it is.
 

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Just a follow-up to this thread - Zak, which software version did your replacement J644 controller have?

Here's my VCDS fault code, is it similar to anything you're getting?
-------------------------------------------------------------------------------
Address 61: Battery Regul. Labels: 4F0-910-181.lbl
Part No SW: 4L0 910 181 HW: 4L0 915 181
Component: J0644 BEM H12 0530
Revision: -------- Serial number: 00000000072078
Shop #: WSC 48120 822 90801
VCID: E4CD350027401FA

Subsystem 1 - Part No: 4F0 915 105 D
Component: von VA0 2612202772
Coding: 344630393135313035442056413032363132323032373732
Shop #: WSC 20700 822 999999

1 Fault Found:
01299 - Diagnostic Interface for Data Bus (J533)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 154
Mileage: 74302 km
Time Indication: 0
Date: 2012.01.29
Time: 16:07:38

-------------------------------------------------------------------------------


Tim
 
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