2009 Silverado 4 wheel drive not working

[Wallace Hicks]

Ok guys I need help.I have a 2009 Silverado and the "Service 4 wheel drive" message is on.when I start the engine all the lights on the knob light up for a few seconds and then go out except for 2 hi which stays on.When I try to switch to 4 high or 4 low the 2 hi light stays on and the others don't flash.There is no sound from the shift motor like it's trying to shift.I did some voltage readings on the TCCM. When switching on the knob the the signal input to the TCCM varies like close to specs.However there is never any voltage sent to the shift motor.My question is --Is the TCCM shot or is it possible it sees a fault and won't send voltage to the shift motor.I have all the volt readings on the TCCM terminals if anyone is interested in helping me. I have checked all the grounds and cleaned them.

 

[OldCracker29]

Sounds like it could be the encoder sensor...

https://www.truckmodcentral.com/threads/service-4wd-mil-dtc-c0327.11432/


Oh yeah...

 

[NMSilverado]

Had a similar problem, turned out to be the selector switch on the dash. seems contact soldering was broken.. replaced selector switch and it was the isssue.. Now works just like new.

 

[Shaggy]

Ok guys I need help.I have a 2009 Silverado and the "Service 4 wheel drive" message is on.when I start the engine all the lights on the knob light up for a few seconds and then go out except for 2 hi which stays on.When I try to switch to 4 high or 4 low the 2 hi light stays on and the others don't flash.There is no sound from the shift motor like it's trying to shift.I did some voltage readings on the TCCM. When switching on the knob the the signal input to the TCCM varies like close to specs.However there is never any voltage sent to the shift motor.My question is --Is the TCCM shot or is it possible it sees a fault and won't send voltage to the shift motor.I have all the volt readings on the TCCM terminals if anyone is interested in helping me. I have checked all the grounds and cleaned them.

Was going to say the same thing as @NMSilverado. Try replacing the selector switch.