The TCCM compares the current internal operating program with a stored operating program. This comparison allows the TCCM in order to evaluate if the TCCM's RAM and ROM are operating properly. Should the TCCM detect a problem with the internal operating program, a diagnostic trouble code (DTC) of 4 is stored indicating the TCCM memory is damaged. Replace the TCCM. Refer to Transfer Case Control Module Description .