The rear sliding doors on the Mazda5 have dinky plastic lock actuators that like to fail. You’ll know if it’s broken - they won’t respond to the lock/unlock command properly on the first try, whether by remote or the interior lock switch. The driver side is part number C23573350, passenger is C23572350.
The process involves taking off the sliding door interior panel, which is thankfully a pretty simple job. From there it’s just a few screws and bolts to remove the actuator. http://www.mazdas247.com/forum/showthread.php?123761729-Sliding-Door-Lock-Actuator-R…">This thread guided me through. Took about 45 minutes total.
I also replaced the cabin air filters while in there. It’s http://i59.photobucket.com/albums/g304/apocaplops/P1050122.jpg">kind of a pain to access the filter cover, located under the left side kick panel of the passenger footwell. The cover itself is held on by 4 philips-head screws, the top two were a pain to get to. The filters were http://i59.photobucket.com/albums/g304/apocaplops/P1050121.jpg">pretty disgusting after what was most likely 6 years and 67k miles.
