Hi, these lock actuators are weak and fail at nearly the same time since you probably use your remote to lock and unlock each time, actuating all even if only 1 is up.
I have had 3 Exc's and 2 of them had to have all 5 replaced. I did 1 at a time on the first one but it was annoying after the third so I did the remaining before they went. The second
truck I did when the first one got weak, all 5 at a time. There is a right and a left door
lock actuator but I am not sure which one the rear takes. Buy them offline and do it yourself. About 30 minutes each, and a bit tricky but after the first one it gets much easier.
The removeal is tough, un-hooking the plastic latch mech is awkward so I just break
them off and dig the broken latch piece out. I also had the same problem with an F150 Lariat 4X4 (1998)
There are details and instructions out there but with a new one in your hand and the door panels off, you can figure out the process if you have moderate skill. At $300 per door from
the Dealership (mine anyway) it is well worth the Sunday Afternoon and $250 for 5 of them and no more accidental unlocked doors.
I also recommend doing the door ajars at the same time - $15 a piece and easy to change once you are in there. On 5 trucks I have had 7 of those fail too, so now I rip them all out in 1 shot and it takes about 3 or 4 hours.
Sweet! Check this out!
2000 Ford Excursion 4x4 - Door Lock Actuator Installation
Pictures and everything!
Justin.