NVG 236/246-NP8 (Two Speed Automatic)

DTC C0550


Circuit Description
At each power up the transfer case shift control 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^ Masked ROM code has failed Checksum test indicating that masked ROM data is no longer valid.
^ ROM code has failed Checksum test indicating that ROM data is no longer valid.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 ROM locations have failed operational test indicating that some portions of RAM are not functional.
^ Motor circuit test has indicated that one of the modules's relays is not able to make contact.

Action Taken When the DTC Sets
The SERVICE 4WD indicator 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.





Test Description
The number below refers to the step number on the diagnostic table.
2. Replacement of the transfer case shift control module.