My 2000 4 Runner limited had the same problem.
The cause was in the fuse box under the steering column.
That is were the relays for the locks are located.
My repair guy used a small extention and just tapped on the four corners of the fuse box and this freed up the relay's and everything is...
I have a 2000 4Runner Limited.
When I put the key into the driverside door to unlock the doors it only unlocks the driver side door.
If I use the key on the passenger door it unlocks all doors.
What is wrong??
