Fault codes covered
28-72
This code will be set if fuse 2 is blown or missing on PCM board. Fuse 2 only powers the LLS. When this fault is active the system will not operate. The code will clear once fuse is replaced with new, undamaged part. LLS are field installed accessories. Check LLS wiring for shorts. See wiring diagram for fuse size and location.
Source: ACHPVSR454-02SM troubleshooting pages.