I’m getting the duty solenoid c error from the power light flashing on the dash. When I test it at the tcu I get the correct resistance it no voltage.i get voltage at the 2wd fuse.  Would this be an issue with the tcu and not the duty solenoid c?

When you tested the resistance, it was with the TCU disconnected?

The signal from the TCU to the solenoid is a pulsed pattern, you need an oscilloscope to see it, although you can get some idea of what's going on with a voltmeter, but it's not really a measurement you can use to say 'good/bad'.

The pin at the FWD fuse is hust a signal line input to the TCU, it's not in the circuit with the solenoid.

I was testing according to these. 
The tcu was connected. 

I believe they are from the full service manual? If they are not correct how do I test it? I have two weeks to get the all wheel drive fixed before my trip and it’s either replace the solenoid  with the solenoid out of a used transmission or replace the whole transmission and rear differential. 

Edited June 11, 20205 yr by Dom

What year and model is the car?

What year is important, and the test they talk about with the fuse isn't measuring at the fuse, it's the wire to the solenoid.

in 2003 the fuse would do one thing, in 2004+ it would do the opposite.

The resistance would be measured with the TCU disconnected.

The TCU solenoid is in the removable tail section of the transmission.

With the FWD fuse out, and with it in, what does the car do when turning in tight circles?

 

2004 and after when the solenoid fails you get front wheel drive, which doesn't hurt anything.

before that when it fails you get full lock front-rear.

It is a 91 legacy yes the solenoid is in the removable section of the tail. 

so I unplugged the tcu from transmission at the back of the motor and still no torque bind. 

If the AWD mechanical bits are working then it should have bound up a little in limp mode, which is what the trans goes into when disconnecting that. You get 3rd forwards and reverse and full AWD.

The TCU can only detect the voltage at the TCU so it's either a busted or shorted wire from TCU to solenoid, or it's the solenoid.