4wd will not engage. My limited has the two position TC with the 4wd engage push button. I get nothing when I press the push button on the shifter. No usual click from the relay/ecu and no actuator running sound either. The indicator light does not come on. The 4wd fuse is good. I verified the front axle does not lock in (spins freely). The VSV’s do not swap automatically, but I don’t think they’re ever getting the signal to swap since nothing happens from the push button. I did verify that the front axle does lock in when I manually swap the vacuum hoses at the VSV’s. (Does not spin)
I am leaning towards it being my 4wd ECU as the issue. Any other advice would be appreciated.
also, help me locate the 4wd ECU!!! Resources are sketchy on that.

thanks,
Brian

Its possible its the ECU though it more on the rare side. I would suspect the actuator its self. As if it will not engage into 4wd. I would think the light would not engage along with the front VSV. Remove the actuator power connector and test for voltage while you have someone push the button on and off see if you are seeing 12 volts going to the motor actuator. If we have power at the actuator the brushes in the motor are most likely warn out and may need a replacement actuator. Testing is the only way to know for sure.

I haven't had to play with this on my Limited so not sure if it's the same but on my SR5 the culprit was the relay in the passenger kick panel.