PIP-4714

CHEVROLET/GMC: SHUTTLE BUS GENERATOR MODIFICATION P0621. DEALER MAY ENCOUNTER CONCERN OF A SES LIGHT ON WITH DTC P0621 FOUND. MANY CASES THESE VEHICLES ARE USED IN A SHUTTLE BUS APPLICATION. SOME UPFITTERS OF THE SHUTTLE BUSES ARE ORDERING THE VEHICLES WITH DUAL GENERATORS AND REMOVING ONE OF THE GENERATORS TO INSTALL AN ADD ON AIR CONDITIONING COMPRESSOR. *PE