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-   -   Q7 no start, no communication (https://www.audiworld.com/forums/q7-mk-1-discussion-112/q7-no-start-no-communication-2880347/)

axl3133 03-22-2015 05:38 AM

Thanks, I am going to test connection between main relay and ecu. Also from the gateway to the ecu next. I cant seem to find any info on recoding the battery, rosstech only has instructions for an OEM battery.

smith2010Q7 03-22-2015 07:31 AM

You follow rosstech, but the only difference is when putting in a new SN, aftermarket batteries you old battery SN change the last digit so the computer knows it is a new battery and it will run the charging system a low rate than a higher rate.

axl3133 03-22-2015 07:56 AM

crap, old one is gone

smith2010Q7 03-22-2015 08:12 AM


Originally Posted by axl3133 (Post 24668484)
crap, old one is gone

Do you have a SN on your new one? you can use it also. used the drop down menu and used Va and put in the digits after VA. has to be 10-11 digits.

axl3133 03-22-2015 02:43 PM

Thanks again, I will check

axl3133 06-03-2015 12:25 PM

SOLVED!!! It was the ECU, after months of checking every connection, fuse, relay, ground, and harness and pouring over pages of diagrams, and finding nothing wrong, I gave into the idea that ECU had failed, however rare of a case that it might be. I took out the ECU and tested for power at it and got power. Still can't believe there is no way to bench test these units. I knew that even if I bought the part I wouldn't be able to code it, so I brought it to the dealer. They took an ECU out of an A8 they had and the car started right up and ran for a few seconds. They then ordered and replaced the ECU for my car and it runs fine. Hopefully it was just part failure and nothing underlying causing it. Thanks to everybody who helped me out here, especially smith2010Q7!

antwone hooks 03-14-2019 03:53 AM

I’m having the same issue U0101 code 2008 Q7 passenger soaked
 
[QUOTE=axl3133;24665083]Hi, was hoping I might be able to get some insight here.. I have an 07 Q7 4.2 with 105K. Last week during frigid cold here in Boston the car stalled shortly after starting up. Did this a few times then seemed ok. Later while driving it completely cutout and would not start or even turn over. Had it towed home. Car will not crank now and I am getting a low battery warning on the dash, esc fault, and adaptive headlight fault. When I put the key to the on position the fan comes on at a very high speed. Also, very weird, the CD changer starts going through the discs. It is a stock radio. All other electrical in interior is fine, lights etc.. The battery tested bad, so I replaced it, was almost time for a new one anyways. There is no communication from the OBD port. I checked for power and ground there and got 12V. But when I checked pin 7 got nothing. So far I have checked all fuses and tested all relays save the few next to the steering column. Anybody have any tips for the next diagnostic steps? Thanks![/Q

jerbo 02-16-2021 02:57 PM

[QUOTE=antwone hooks;25289170]

Originally Posted by axl3133 (Post 24665083)
Hi, was hoping I might be able to get some insight here.. I have an 07 Q7 4.2 with 105K. Last week during frigid cold here in Boston the car stalled shortly after starting up. Did this a few times then seemed ok. Later while driving it completely cutout and would not start or even turn over. Had it towed home. Car will not crank now and I am getting a low battery warning on the dash, esc fault, and adaptive headlight fault. When I put the key to the on position the fan comes on at a very high speed. Also, very weird, the CD changer starts going through the discs. It is a stock radio. All other electrical in interior is fine, lights etc.. The battery tested bad, so I replaced it, was almost time for a new one anyways. There is no communication from the OBD port. I checked for power and ground there and got 12V. But when I checked pin 7 got nothing. So far I have checked all fuses and tested all relays save the few next to the steering column. Anybody have any tips for the next diagnostic steps? Thanks![/Q

Hello there My name is Jerry and I have the same PROBLEM did you find out what was wrong?

jerbo 02-16-2021 02:58 PM

did you find out what was your problem? I have the same issue 2007 Q7


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