I recently bought a 1997 Audi Cabriolet Convertible 2.8/A4 FWD. I love the car but the Speedometer stopped working on the way home. I have changed all the speed sensors on the transmission. And the Transmission had just been rebuilt before I got it. The Speedometer Sensor is new and sending voltage but the speedometer will work for a few minutes and then start jumping and quit. I have been told that it is probably the transmission control module. But I can not find it. Please Help, If you have a diagram of where it is located. I have been told it is under the passenger seat front floorboard, and under the dash on the drivers side, and under the back seat. I have checked all three locations and can't find it.