My tcase will not engage into 4x4. When i start the truck both 4x4 and 4lo lights come on and go off. When i hit the switch to 4hi it does nothing, no clicking of the module or light. If i turn it to 4lo, the light goes on there is ac couple clicks, but it never engages. If i try to turn the switch back to 2wd, there is no clicking and the 4lo light will stay on. Ive tried 2 shift motors with the same results. Could it be the switch? The module is a year old.