my service 4wd light is on, it will go into 4lo not auto or 4hi just flashes then back to 2wd. actuator works if I put vacuum to it otherwise will not. Vacuum lines are good and it has vacuum. actuator switch is new. Cleaned the contacts on the TCCM they were clean put some dielectric grease on them. Dash switch checks out good. seems it's either the TCCM or the encoder motor is there a way to test the encoder motor, are they a common problem. If I leave it in 2wd and restart it the service 4wd light will not come on untill I push 4hi or auto.