So I've been having problems with my speed sensor(automatic) ever since my swap. I had no codes and checked the wiring at the plug and traced at the computer.The wiring and gauges was working fine but then I decided to take apart the sensor while waiting on a working one. After opening the top of the sensor ( the three black screws) it was full of fluid. Apparently during my swap, the tranny was turned upside down. So I switched sensors with the working one not fill of fluid. I never would have guessed it to be due to fluid in sensor.So if your having spedo problems with auto trans, check sensor for fluid build up or over fill. Hope this helps someone.

Note: It looks the sensor works like a hall effect sensor like on the chevy ignition system.