Q7 Battery Drain Problem
I am new to these forums but a long term Audi owner (Allroad, A4 Cab and now Q7). Hoping to get some guidance so any help or advice very much appreciated.
We have an 11/06 ('07 model year) Q7. It is fitted with every single option available and hence why we still own it after almost 5 years. It has been, and is, a superb vehicle but starting to give problems. The latest issue is one of inconsistent battery drain problems.
We first noticed this issue when one morning the electric tailgate would unlock but not lift. We found we could only operate it when the car was started which immediately led us to suspect a battery issue. Indeed, on checking the battery meter it was at just 10%. This was after an overnight sat on the drive. In addition to the systems shutting down (tailgate, keyless, etc) occasionally we have noticed when the battery has drained that when you use the audio system you just get a massive booming from the sub and cannot listen. We have to turn the whole audio system off, wait a good hour or more and then turn back on and everything is OK. It has done this 2 or 3 times since the battery drain issue started, but not every time the battery has drained.
We continued with this problem, on and off, for about 3 weeks before the car was taken to our local franchised Audi dealer for battery checks. They came back and said under load the battery was not holding charge and so recommended we have a new battery fitted.
I declined, as the battery drain problem was intermittent and would go for 3 or 4 days with no drain and then in a matter of hours it would drain to 10% with many of the vehicles systems shut down (protection mode I guess). I started testing things myself by both checking the vehicle visually after switching off and leaving for a couple of hours and also by starting to pull fuses one by one. After a couple of weeks the best I could determine was the DSP amp causing the battery drain. Whenever I pulled the 30amp fuse (in the boot area) serving the DSP amp the battery was never drained by the following morning. So, off to the dealer it went again with this info.
After 2 days they surprisingly said the DSP amp was faulty. To be more precise, a control unit within the DSP amp was faulty and it would cost £1,000 to replace the amp. Ouch!
Whilst the dealer had interrogated the battery manager history they told me "it's all code and will take one of our technicians about 3 hours to decipher it" and therefore they determined the DSP as faulty by simply measuring the current drain on the battery with the DSP fuse inserted and then removed. Basically, with the fuse inserted the current draw was 5.16A but just 0.03A with it removed. I do not know how long the vehicle was left between tests etc.
So, to my questions.
1. How can I interpret the printouts they have given me, which include test outputs and battery history?
2. How can I be sure that it is indeed the DSP amp that is at fault?
3. Is there any way of getting the DSP amp control unit fixed rather than having to replace with new?
4. Who can offer a service to fix this at lower cost than a franchised dealer?
5. Any other help?
PS. I have a scan of the full printout (c. 25 pages) if anyone can help.
Last edited by wattsn; 11-03-2011 at 01:40 PM.