Don't mean to jump in on the OP post, but since it looks like his issue was easily resolved, perhaps you can all help me with a very similar conundrum that doesn't seem to have such an easy solution:
07 SR5 V6 w/around 140k- my wife's rig.
I recently built a gravel driveway down to our lower back property and took her rig down there to grab a small motorcycle trailer that I park down there, and put it in 4wd on the way back up to avoid chewing up the new gravel road.
The rig was in (P) when I shifted into 4hi. It went into 4wd just fine. I noted that the green 4wd icon was solidly illuminated, and the yellow diff lock symbol was flashing. I thought this was odd because I never hit the diff lock button. The yellow VSC off light is also solidly illuminated.
Once back up to the front of our house I disengaged 4wd, and noted that the symbols on the dash remained as described above. No big deal, as I've occasionally had our 4runner take a little bit to disengage 4wd. However, this time it simply never disengaged. We drove the rig about 15 miles that evening, and I tried anything and everything to get it to disengage, including coasting forward and back and finding a loose road to ensure no strain was left on the drive-train.
Making the situation worse is that the vehicle as stuck with the diff lock on! Even though the icon is blinking, it is most definitely on. I've had fully locked rigs before, and know the strain this puts on the drive-train. I brought it home and parked it ASAP.
The 4wd switch is doing absolutely nothing. It does not beep when trying to switch to 4lo when in (P), as it normally would. The actuator motors on the transfer case don't make any noise at all when adjusting the switch, and it also will not shift to 4lo when in (N). My parents also have the same model 4runner, and their actuator can audibly be heard on their rig with the ignition in the accessory position, shifting between 2wd-4hi, and then 4hi-4lo. With ours - nothing.
I've tried swapping the 4wd ECU from their 4runner, and that did not help the situation any. I know the transfer case actuators are problematic on these things, but I'm still not sold that is the issue, as it seems most people have issues with it initiating 4wd after a long period of disuse. In this case it shifted to 4wd just fine, and is now seemingly is locked there.
Is there a possibility this issue is tied to a faulty front differential actuator instead of the actuator on the transfer case? I'm thinking perhaps the front diff actuator engaged enough to lock the front end, but never hit the limit switch, which then locked up the ECU and entire system, so it won't even try to disengage?
I've banged on both actuators with a rubber mallet, but no joy. Very confused, as I have not been able to find a single documented case where someone experienced this exact issue.
Thanks all