The 2006 Ford Ranger's power train control module stores error codes, known as diagnostic trouble codes, whenever a malfunction is detected in any of the Ranger's power train systems. These codes correlate with troubleshooting tests that will lead a diagnostic technician to the source of the malfunction. Retrieving the codes from the module is fairly simple; however, the codes are merely a symptom and you must correct the actual problem before the codes are erased.
Remove the cover from the diagnostic port underneath the Ranger's driver's-side dashboard. The port is roughly 2 inches wide by 1/2 inch tall. The cover on the port is made of malleable black plastic and has the letters "DTC" embossed on it for easy identification.
Plug the data-link cable from your scan tool into the diagnostic port.
Turn the ignition key to the "Run" position, and turn the scan tool on. Follow the scan tool's specific operating instructions to run a self-test on the Ranger's power train control module. This test will retrieve the error codes and display them on the scan tool's readout screen.
Write the codes down so you have them for reference during the diagnostic procedures.
Finish the self-test per the scan tool's specific directions and when prompted to save or erase the codes, choose to save them. Do not erase the codes until you have diagnosed and corrected the Ranger's malfunction.
Disconnect the data-link cable from the diagnostic port, and replace the port's cover to prevent dirt and dust from entering the port.
You can pick up a scan tool from an auto parts store. Scan tools come in a wide variety, from inexpensively priced code readers to highly sophisticated diagnostic devices that can cost several thousand dollars. For this task, a simple code reading scan tool will do fine. Make sure the one you purchase works with Ford software.