Regarding your E-Locker, I would bypass the ECU and test the motor/actuator first before removing it from the diff. If you can apply power directly to the motor and get it to work, then you can narrow the problem down to the E-locker ECU. If you give it direct power and it still doesn't work, you know the problem is the motor/actuator itself.
There should be a harness that connects the E-locker to the chassis. One end plugs into the E-locker motor, the other plugs into the next section of the harness on the chassis roughly 2 feet up the line. I'd disconnect the plug that connects that short ~2 foot section on the Chassis side, and position it so you have access to the terminals in the plug.
Make yourself three 3-foot sections of wire. On the first, attach female blade connectors on both ends. On the next two attach a female blade connector on one end, and strip back a half inch of sheathing on the other end.
To LOCK the diff manually:
1. using the wire w/two female blade connectors, create a jumper between the plug terminals corresponding to the GREEN wire and the GREEN/BLACK wire.
2. Using one of the other two wires, attach the female blade connector to the terminal on the plug that corresponds to the GREEN/RED wire
3. Using the last wire, attach the female blade connector to the terminal on the plug that corresponds to the WHITE/BLACK wire. Since there are two, in the diagram below, I am referring to the one labled #7. If you can't tell which of the two WHITE/BLACK wires corresponds to #7 (which may be tough because the 4Runner plug is rectangular, not round) just try them both. One is a ground for the E-locker motor, the other is a ground for the locked position switch.
4. Once you've made connections 1-3 above, connect the wire off the terminal corresponding to the BLACK/WHITE wire to 12V battery (-), then connect the wire off the terminal corresponding to the GREEN/RED wire to to 12V battery (+).
If the motor is working properly you should hear it lock the diff.
To UNLOCK the diff manually:
1. using the wire w/two female blade connectors, create a jumper between the plug terminals corresponding to the GREEN/RED wire and the GREEN/YELLOW wire.
2. Using one of the other two wires, attach the female blade connector to the terminal on the plug that corresponds to the GREEN wire
3. Using the last wire, attach the female blade connector to the terminal on the plug that corresponds to the WHITE/BLACK wire. (See addt'l steps above in step 3 to LOCK)
4. Once you've made connections 1-3 above, connect the wire off the terminal corresponding to the BLACK/WHITE wire to 12V battery (-), then connect the wire off the terminal corresponding to the GREEN wire to to 12V battery (+).
If the motor is working properly you should hear it unlock the diff.
(NOTE: I might have mixed up which procedure is lock vs. unlock above. Since your diff is currently unlocked, try the LOCK prodedure first. If it does nothing, I may have mixed them up, so try the UNLOCK prodedure. If neither procedure gives you a result, your E-locker motor is dead. The limit switches will prevent you from damaging anything if for instance you run the UNLOCK procedure on a diff that is already unlocked, or vice versa)
If you test it this way and the motor works as it should, then the problem lies with your ECU or chassis wiring.
There's lots of info on the web RE rebuilding the E-locker motor... Here are a few I've found:
gear install
Toyota Tacoma Elocker Actuator Repair
UltimateYota.com - E Locker motor repair
Rewind your E Locker Electric Motor!
