Some owners of 2004-2012 Chevy Colorado 4WD trucks may comment on a “Service 4 Wheel Drive” message displayed in the DIC (driver’s information center). Technicians may find DTC C0327 stored in current or history in the TCCM.
The concern may be intermittent but the customer may say that it happens mostly on the initial drive cycle or after several hours of sitting in cold or damp conditions. The concern may also be intermittent when attempting to shift into or out of 4WD.
Perform diagnostics outlined in the service manual. If no root cause is determined, then suspect 550 ground circuit for the transfer case encoder motor channel circuits.
One suspect location is connector 2, terminal F7 in the underhood bussed electrical center.
Check for proper terminal tension, corrosion, etc. Replace the terminal if any concerns are found.
Usually this condition is easiest to duplicate under high electrical load conditions, like starting the engine and shifting the transfer case.