NVG 136-NP4 (One Speed Automatic)

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^ Masked ROM code has failed checksum test indicating that masked ROM data is no longer valid.
^ ROM code has failed checksum test indicating that ROM data is no longer valid.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. Diagnostic System Check - Transfer Case