I have an 03 F-150 Scab XLT in which when you either attempt to lock or unlock the doors via the keyfob, keypad, or lock button on the door panel, the lock makes a horrible sound, and malfunctions to where it will not perform the lock/unlock procedure. I can still manually lock/unlock the door via the keyhole/key method on the door itself, but its getting old fast... Everything is the factory original setup here, no aftermarket. The lock literally just started malfunctioning one day, and never worked properly again.

From what I have gleaned from searching a few threads, it is probably the power lock actuator that is blown and needs replaced. Thoughts, anyone?

EDIT: The battery is good, and therefore cannot be the cause of this issue.

 

If you want to test the lock actuators one at a time, this would narrow down if it is an issue with the lock actuators itself, or the CSM ( Central Security Module )

 

How would I test the lock actuators one at the time to determine if they are the cause?

 

the door actuator is going to be your problem, ford and honda are notorious for door lock actuators going bad. but if you want to test it first just pull your door panel unplug the two wire plug going to the motor and take a cordless drill battery and two piece's of wire and touch the battery to the wires going to the motor if the motor is fine it will lock and unlock and you chance the polarity on the battery. if the motor is bad it will hesitate or make a grinding sound.

 

As described above, use an external 12 V power source to apply power directly to the lock actuator.

1 direction is lock, reverse the polarity is unlock.

 

Thanks guys. I'll check it out and post my findings. I just replaced a window regulator in my wife's Jeep, and now this needs fixed in my truck.