Door lock actuators don't consistently work


Asked by Nov 26, 2013 at 10:05 PM about the 1999 Ford F-150 XLT Extended Cab SB

Question type: Maintenance & Repair

Does the door lock actuators on this truck use vacuum for the door locks? When running
the power door locks work fine for 2-3 times, then stop completely moving the locks, wait
a few seconds and they work again. When not running they move but do not lock or

6 Answers


The door lock actuator is electric, not off a vacuum. Is the problem with one door in particular or all of them.

2 out of 2 people think this is helpful.

Both doors

2 out of 2 people think this is helpful.

Now knowledgable with your particular model, the theory is the same, or should be. Power to the locks is usually supplied to the drivers side, then a jumper supplies the passenter side. You either have a ground problem, a corrosion problem, or loose connection in the drivers side door. Small hands are probably required here to get inside the door. Check the connection (plug) to the actuator, clean with electrical cleaner then check voltage.

2 out of 2 people think this is helpful.

Do the locks work correctly with the key fob? Also, check the switch (button) on the drivers side door panel. There is a chance your switch on the door is bad, corroded, or has a loose ground/power connection. This can be checked with a jumper wire. If the locks work with a jumper wire, (momentary touch) change the switch.


They do the same with the fob as the switch on the doors. It seems strange that they will work fine for the first 2-3 times when truck is running. Wait a few seconds and they work another 2-3 times. When truck is not running they consistently do not work, the more you press the button when not running the less they move when pressed. With this in mind it seems vacuum related,


There is absolutely no vacuum line operating the locks on the vehicle. Your problem is electrical. When not working check the voltage at the door switch. It does sound like a contact problem. Movement of the vehicle can jiggle a connection causing it to work or not work.

1 out of 1 people think this is helpful.

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