Q7 no start, no communication
03-22-2015, 05:38 AM
#41
AudiWorld Junior Member
Thread Starter
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.
03-22-2015, 07:31 AM
#42
AudiWorld Member
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.
03-22-2015, 08:12 AM
#44
AudiWorld Member
06-03-2015, 12:25 PM
#46
AudiWorld Junior Member
Thread Starter
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!
03-14-2019, 03:53 AM
#47
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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
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[QUOTE=antwone hooks;25289170]
Hello there My name is Jerry and I have the same PROBLEM did you find out what was wrong?
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
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