Power locks on sliding door and rear hatch

[pryter]

My power lock switch (89 van) locks and unlocks the driver and passenger doors, but nothing in the back two doors. Is this normal or defective? Anything I should be looking for in troubleshooting this?

[llamavan]

The power lock switch should unlock everything at once. The slider and lift gate locks, motors, and mechanisms tend to be fussier. You'll want to check whether the respective motors are working first (if they are, you'll hear the "clunk" from each location when the switch is activated). What comes next depends on what you learn about the motors.

Gwen

[Duke]

I'm interested to hear what you come up with. The power locks for the slider and rear door on my van will unlock, but not lock. I can hear the solenoids trying activate the mechanism, and can even see the lock knobs move when I press the button, but they won't go down. I lubed the rear mech and it definitely made a difference when doing it manually, but still no dice with the auto locking.

Anybody have any advice on what to look at next? I would really like to get it working properly.

[Traveling Amman]

I had the same problem with my door locks. I finally got them to work properly, I sprayed lots of lube all over the lock mechanism and then used my key in the door and my hand on the inside lock knob. Together I worked it back and forth, lock-unlock, more lube more back and forth with key and knob. After maybe 5-10min of doing this the locks were smother and power Locks were working again with the switch. I guess the locks get gummed up over the years and become sticky, lithium grease becomes rock hard and can jam up the locks.