98 T100, neither side power door lock work. relay clicks, actuator arm on driver side shudders

 

Sounds like you wiring is good. Actuators have likely failed.

Both of the front actuators in my '95 4Runner have failed, but both the rear ones still work.

 

Aloha,
I have a 96 T100 SR5 and sadly I am in the same boat as you :/. There is a "Door Control" relay box located under the driver side kick panel by your feet. There should be a little brown box that is clipped onto a metal bracket. The OEM part number off of mine is 85980-34030. Everywhere I have looked for this part it has me paying over $400 for it. Best bet is to find it from a scrapper...still looking... lol

Will update as soon as I can get my hands on one.