DTC 004

DTC 004






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

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^ Masked ROM code has failed Checksum test indicating that masked ROM data is no longer valid.
^ ROM code has failed Checksum test indicating that ROM data is no longer valid.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

CONDITIONS FOR CLEARING THE DTC
The condition for setting the DTC is no longer present and a momentary loss of battery power at the battery positive voltage circuit (CKT 40).

DIAGNOSTIC AIDS

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

2. This step replaces the transfer case shift control module.