The transmission computer in your Ford vehicle is actually part of the electronic control module, or ECM. This computer monitors the transmission as well as a variety of other vehicle systems. When this computer generates an error code, it stores the code until it is retrieved. Normally, when there is a problem with one of the sensors in your transmission, the ECM will generate a code and the "check engine" light will illuminate on the dash instrument panel. To troubleshoot your transmission codes and computer, you'll need a special tool called an OBD tool (on-board diagnostic tool) that can read the error codes generated by the computer and provide you with a numeric readout.
Locate the open OBD port on the left side of the Ford's fuse panel in the driver's-side foot well.
Plug the OBD tool into the open port (there is only one that is large enough).
Turn the ignition to the "II" position and wait for the scan tool to retrieve the error code. This numeric code can then be used to determine what is wrong with your Ford's transmission. You will need your Ford vehicle's service manual to translate the code.
