I have a 2005 3/4 ton suburban and when I try to switch into anything but 2WD the light flashes and then nothing happens or it gives me the blinking red light on the selector panel. Any thoughts.
After pushing any 4WD button (4WD auto, 4WDH or 4WDL) the light just blinks and either goes back to 2WD or gives me the red light in the neutral field. I get no service errors just wont engage.
Theres a problem with the 4WD system. Likely errors are the transfer case motor, a broken or disconnected vacuum line, or the front axle vacuum acuator.
This is most likely encoder (transfer case) motor problem.
I agree it is most likely the front differential actuator motor or the encoder motor or switch. NOTE:......With a standard OBD II code reader you unfortunately will not be able to pull service error / diagnostics codes from the BCM, transfer case 4x4 etc. GM requires that you have a much more sophisticated AND expensive OBD II reader called Tech II, or you can purchase a less expensive version that is called an ENHANCED OBD II code reader.
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