NVG 126-NP4

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

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0550 ECU Malfunction

Conditions for Running the DTC
^ The ignition is ON.
^ System voltage is 9 - 18 volts.

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^ Masked ROM code has failed Checksum test indicating that masked ROM data is no longer valid.
^ ROM code has failed Checksum test indicating that ROM data is no longer valid.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.

Action Taken When the DTC Sets
^ The SERVICE AWD indicator remains illuminated for the remainder of the current ignition cycle.
^ The transfer case control switch does not display the current position LED while DTC C0550 is current.

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

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