Engine wiring harness ground point
 

I have had a lot of issues lately with the engine in my 2005 A4 1.8T. Started with the radiator fans not running. Replaced the CTS, fan control module, radiator thermal switch, and the 219 relay. Still no fans. I have also had issues starting. The car takes several turns of the key to start and then rough idles for a few seconds before smoothing out. It is kicking a cylinder misfire on 3 cylinders. It is also draining the battery if left to sit over long periods. I am getting 4.6V at the thermal switch which I believe should be battery voltage. Is it possible that this is caused by a bad ground? If so does anyone know where the ground point is at? I have seen a break down of which plug does what but can't find the location of it on the vehicle.