NVG 236/246-NP8 (Two Speed Automatic)

DTC C0550





Test 1-2

Circuit Description
At each power up the transfer case shift control module runs a self test on the following:
^ EEPROM Check sum
^ ROM Check sum
^ RAM Check sum
^ RAM Malfunction
^ Relay Malfunction

Conditions for Setting the DTC
^ Critical operational parameters stored in EEPROM have failed Check sum test indicating invalid data.
^ Masked ROM code has failed Check sum test indicating that masked ROM data is no longer valid.
^ ROM code has failed Check sum test indicating that ROM data is no longer valid.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 indicator (4WD/AWD) 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.

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