Hi I'm new to the forums but in desperate need of some advice.
I've got an audi q7 3.0 tdi with a problem with the radio it comes on when the car is parked up. Been to mechanic and audi aswell as a auto electrician with no joy it did have a convenient unit??? Put in befor all this happened.

Anyway I tried myself to stop it coming on. I've found the radio fuse in the boot which has a constant live so I thought if I take a ignition feed and run that through the fuse and into the pin goin to the radio problem solved. However finding an ignition feed was hard work found a 6v feed to the light switch so found a post that said there will be a black/yellow wire which is an ignition feed. Spot on behind the dash just above the pedals there was a 12v feed so I ran a wire the full length of the car and when I switched the ignition on the radio came on happy days. Then it all went **** up the car will not start turns over just won't fire I've tried pulling fault codes up but nothing really points me in the right direction. Anyone know if I've done something wrong or its just coincidence. It did struggle starting as the battery is low I've tried jumping and charging with no success.

 

What does "parked up" and "convenient unit" mean? Your post is a bit hard to follow due to lack of punctuation too.

Radio? Factory or aftermarket?

You found 6 volts on a wire that feeds the light switch? On a 12 volt system?

Have you tried removing the wire you ran and see if the thing will start? It kind of sounds like you may have shorted something out. Never ever ever run power TO the fuse panel, always run it FROM the fuse panel to the device you are trying to power up.

 

Parked up as in left outside locked up. I get out switch off everything and lock the car. Then when I return to the car the radio is playing. It's a standard radio mmi system and was told by audi it had a new convenient unit in whatever that is I'm sure it's something to do with the radio etc.

I found a 6 v feed from the light switch but didn't run it from there I used a 12v feed from a black and yellow cable under the dash (goes to a relay) I've unplugged what I did still no joy. When I wired it in I used a spade connector into where the fuse was down the none live pin. The radio was working find on the ignition so I put all the trims etc back then went to start the car and it just turns over

 

It sounds like possibly the anti theft is possibly causing the issue. I'd disconnect the battery and let the car sit for several hours. Perhaps this may reset the anti theft system and allow you to start the engine. Other than that, it's hard to tell what it might be with the complex nature of these things. Almost too complex these days.

 

Had it sat over night also tried spare key charged the battery all day still struggling to find out the problem

 

Hope you can get it sorted out. Hopefully it's something simple. But nothing is all that simple on these things anymore.

 

Right I've gone through fuses no problem I've also cracked an injector off and there is no fuel there is at the fuel filter when cracking it spurts out like mad.

Does anyone know if the theft thing has triggered the immobiliser will the car still turn over?

 

Fuel should still squirt from the fuel rail at the engine if it squirts out at the filter. Kind of sounds like the fuel is not reaching the engine from the filter. Doubtful that a filter would completely clog but have you removed it to make sure fuel will flow though it?