X-Traction

I didn't even know there was an acutator inthe rear end, unless you mean the actuator for the tailgate lock.

By the looks of the Nissan manual, the control box in the passenger side of the cargo area is the automatic transmission control unit. There does seem to be wiring for the door locks in the driver side of the cargo area. There is a "lock timer" (4D) "Inside of L.H. side innner side panel". So probably you have found that.

I don't recall your exact symptoms post, but it seems to me the door locks were locking or unlocking on their own. If that's correct...

Power door lock actuators have two types, masters and slaves. A master, if the "plunger" moves past a certain point, either by turning the door lock key, pulling or pressing the lock knob up or down, or by pressing the lock/unlock button, doesn't just unlock/lock itself. It also sends a signal (low power) to the main control unit (which for some reason Nissan calls a "timer") which then tells the other doors to lock/unlock. It uses relays to do this, and the lock/unlock "signal" actually is the power needed to move the actuator. Slave actuators only take lock/unlock commands/voltages, and can't tell the other doors what to do.

Typically, rear doors have slave actuators, and front doors have masters. Our '91 seems to have a master actuator only on the drivers door. The tailgate is also a slave, I believe.

So, if, through wear, damage, loosening parts etc, one of the master actuators comes to rest very near the point where it commands the other doors to lock/unlock, it can easily pass that point and send a lock/unlock signal. Like when you go over a bump or slam the door. Alternatively, if it can't reach the lock/unlock point, it can't send the signals.

I would start with the doors, not the main control unit. Removing the door panels is an adventure in itself, especially the back doors. Either on this forum and/or the nissan4wheelers site, I've described how to do this. It's usually a master actuator problem anyway, so start with the front ones. Just unplug the actuators one at a time, and see if the problem goes away. Of course, you'll be back to manually locking any disconnected door.

You may be able to swap the front right and left acutators and see what happens. I couldn't swap them on ours because the right and left front ones are different, and both are different from the back ones. If you go to a wrecker to get a replacement, take yours with you, because they also varied from year to year (been there, been stung by that).

If you track it down to one actuator, fiddle around and see if the actuator is tripping the lock/unlock signals in a reliable manner. Then you can figure out if it's the rod assembly, or open up the acutator and see if everything's ok in there. Make a diagram or take a picture before starting to remove parts inside it, because ours was tricky to reassemble properly. Noting how the rods connect is also a good idea.

As I mentioned, the circuit board in one of ours had not been seated properly during assembly, and the moving parts inside gradually wore through an electrical trace. I suspect ours wouldn't be the only one with that problem, and a new Nissan actuator is over $200cdn. (You can buy an entire 3-rd party power door lock system for 4-doors for $40cdn.)

Hope that helps. Just chew away on it, do some work then go away and think about what happened, and eventually you'll be very pleased when you sort it out.

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'91 Pathfinder SE 5spd (now sold)
'06 Suzuki Grand Vitara JLX-L