Diff actuator problem

Reggy,
My rear diff never seems to lock in, while the front one always locks in, ie: warning lights flash, then stay illuminated. Apparently, water/moisture easily accesses the actuator down the breather tube & causes rusting & seizure. Higher breather hose & there is an after market cover that better protects the general area.

Bob

Mine was doing the same - turned out just to be the switch.

https://www.ebay.com.au/p/15017008175?iid=353161984286

Common problem

Shane

With the factory lockers I find I need to drive it a little with the steering turned to get the rear to lock in.

Not a Toyota, but my BT50 (Ranger) has a nasty habit of chewing off the power wires to the locking diff inside the housing.
Its a reasonably common issue, but as the diff locks get rarely used and the light tells you its working, most don't know it isn't.

They take a bit to engage.
I have a 2017 79 single cab GXL with front and rear lockers.
It usually takes a bit of left and right turning to get them to engage, not just in a straight line. Sometimes about 50meters.
You also should use them fairly often to keep them all in working order. Same as 4wdrive high and low range, use it or lose it!
There all getting a workout currently on the Cape!