CHEVROLET/CADILLAC/GMC: SIR MIL WITH DTC B0081. CAN BE SET IN THE SDM AND PPS. IN MOST CASES, THIS DTC WILL SET DUE TO A COMMUNICATION FAULT AND DOES NOT ALWAYS REQUIRE A MODULE REPLACEMENT. INSPECT THE PPS AND SDM POWERS, GROUNDS, AND COMMUNICATION CIRCUITS AT ALL: IN LINE CONNECTORS, PPS CONNECTOR, SDM CONNECTOR AND SPLICE PACKS FOR BEING FULLY SEATED, BACKED OUT TERMINALS, AND PROPER TERMINAL TENSION USING THE CORRECT TEST PROBES. *PE