C0550
DTC C0550
Circuit Description
At each power-up the transfer case shift control module runs a self-test on the following functions:
* 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.
* The 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 not currently valid.
* ROM code has failed Checksum test indicating that ROM data is not currently 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 4WD indicator will be latched on and the system will be disabled.
* The transfer case control switch will display the current position LED while DTC C0550 is current, but further shifting will be disabled.
Conditions for Clearing the DTC
* Replace the transfer case shift control module.
* Perform the Diagnostic System Check - Vehicle. 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.
