Power Doors are not working properly.

Quite a lot of cars have automatically locking doors - when the car reaches around 15 mph the doors lock or a minute after the ignition key has been removed. Other than these times the system must receive a lock doors command either from the plip or by using the key to lock the driver door and sometimes the front passenger door.

You didn't say whether the problem was happening while the car is moving or when stationary but that aside, when a command to lock the doors has been received the system will attempt to comply but if it can't comply it will often make subsequent attempts and sometimes it will keep attempting to lock the doors.

Usually the reason it can't comply with the command is because a door isn't fully closed or the system thinks a door or the tailgate isn't fully closed because at least one of the devices in each door that should tell the system all the doors are closed isn't working.

That device on some cars is a switch buried in the door catch that is operated when the door striker is fully engaged in the catch. Often maladjustment and a lack of lubrication causes an abnormally high degree of wear in the catch and especially of the striker preventing the striker fully entering the catch and operating the switch.

check the interior light switch is working on all the doors. these control the security system.

(door lock actuator)all doors have one in them, they weeken, and sometimes work to open, and some times to lock, or not at all. only fix is to replace each of them as they go out, usually cost abt 20 to 40 bucks a piece

There could be a lock controller somewhere that is not working.
I don't have a wiring diagram for your truck.

Generally, the power window motors are grounded thru the doors, or the switches provide ground. In your case the motors are probably grounded thru the doors.
The master switch "overrides" the door switch so you have extra wires that do the same thing. The E wire probably gives the door switch power and the A and C are up and down. The B and D are override circuits from the master that bypass the door switch.
Sometimes the motor is grounded thru the switch then thru the door.

It makes an annoying whirring noise right? You need to replace the lock solenoid.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

both the rear passenger side wont unlock ???? How many doors are on the passenger side ? Or both back doors don't unlock ? Two relays lock / unlock the back door's Not the lift gate . The BCM controls the relay's . The relay's are located in the rear fuse box . Under back seat .

Will the power lock work from the passenger side button?
If it does, its just your switch assembly.
Hth.

sounds like a ground issue to me have all grounds checked could be jus bad ground.

Check the wiring between the drivers door and the A pillar(the body of the car). Sometimes the harness breaks from opening and closing the door.

Do you have he owners manual? instructions are in there for the keyless entry system. If not go to this link:

http://www.motorcraftservice.com/pubs/content/~WOTEXP/~MUS~LEN/41/96expog1e.pdf