I have a 1997 Audi A6 which won't start. The problem is that when you turn the key in the ignition all the lights come on and then go out as usual but the engine doesn't turn or starter motor make any sounds. It's as if the ignition has been disconnected from the engine. Also the remote central locking has stopped working.

Has anyone come across this problem before??

 

I have a 1996 Audi A6 Quattro which has a problem with the locking, unlocking, alarm module. There seems to be a bad switch in the drivers door, so the car is unlocked, but the alarm is still on. This prevents the engine from starting. The alarm then goes off until the key is used in an outside door.
Your 1997 alarm module may be accessed using VAG-COM from www.ross-tech.com. However, with the 1996 alarm module this is not possible.
The alarm module is located in foam rubber padding next to the battery under the rear seat. Check to see if water got into the module from bad weatherstripping or a leaky sunroof drain.

 

Take the battery out and bring it to an autozone or something and have it load tested. If it passes, i would say that either the starter is bad, or the ignition switch isn't transferring power to the starter. You can also try having someone bang on the starter solinoid while you try and crank the motor. If the engine magically starts turning over, then its a bad starter.

 

Also check the motor to frame ground... Run a jumper cable to see if that makes a difference.

If it does remove both ends of the wire, clean the surfaces and reinstall.