C0550

Circuit Description
At each power up the module runs a self test on the following:
^ EEPROM Checksum
^ ROM Checksum
^ RAM Checksum
^ RAM Malfunction
^ Relay Malfunction

Conditions for Setting the DTC
^ Critical operational parameters stored in EEPROM have failed checksum test indicating invalid data.
^ Masked ROM code has failed checksum test indicating that masked ROM data is no longer valid.
^ ROM code has failed checksum test indicating that ROM data is no longer valid.
^ One or more RAM locations have failed operational test indicating that some portions of RAM are not functional.
^ Motor circuit test has indicated that one of the module's relays is not able to make contact.

Action Taken When the DTC Sets
The SERVICE indicator (AWD/4WD) lamp will be latched on and the system will be disabled.

Conditions for Clearing the DTC
^ Replace the transfer case shift control module.
^ Perform the Transfer Case Diagnostic System Check.