Service Update. Certain vehicles may exhibit the high voltage bulkhead battery disconnect unit (BBDU) positive and/or negative contactors or relays, permanently or intermittently welded in the closed position. Contactors welded in the closed position will set DTC?s P0AA1 (positive), P0AA4 (negative), and P0C76 (hybrid). The malfunction indicator lamp (MIL) may also illuminate and vehicle may not start with this condition. Dealers will reprogram the hybrid powertrain control module.
