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- Masked ROM code has failed checksum test indicating that masked ROM data is no longer valid.
- ROM code has failed checksum test indicating that ROM data is no longer valid.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 the module's relay 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. Refer to Transfer Case Control Module Replacement.
- Perform the Transfer Case Diagnostic System Check. Refer to Transfer Case Diagnostic System Check. Initial Inspection and Diagnostic Overview