the tailgate lock wont turn
My car has 140000 miles.
My car has a manual transmission.
Hey there. Thanks for writing in about your tailgate lock on the 2006 Ford F-150. If your tailgate uses a manual key-operated locking system, it’s quite possible that your lock is stuck or frozen due to debris, gunk or other "stuff," that might have found itself inside the locking mechanism. There is an access panel on the back of your tailgate that will allow you to inspect the back-end of the locking mechanism. Sometimes using some WD-40 to spray inside the key lock will help to loosen the tumblers inside the lock and easily fixing your problem.
If the locking mechanism is electric, the problem could be fuse related, a frayed wire or a broken solenoid that is causing the issue. The best thing to do is determine which type of lock you have first, (as it’s not indicated in the question unfortunately) and visually inspect the lock from the access panel on the back of the tailgate. A professional mechanic can also visit you at work or at home to diagnose the problem and replace the tailgate lock assembly if necessary.