1997 gmc four drive problem

[kevans1993]

Have problem with my 1997 gmc 1500 . The encoder motor engages with the ignition off. Four wheel drive switch light blinks four low , key in on position it stops and drives in 2 wheel hi. Replaced encoder motor with a used one . Grounded pin 13 to check four wheel drive codes. Got code one loss of power to tccm . Not sure where to check next. Any help would be appreciated. Thxs.