THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN HOW TO DIAGNOSTIC AND REPAIR VEHICLES THAT MAY HAVE FUEL GAUGE THAT SHOWS EMPTY AND THE LOW FUEL LEVEL INDICATOR IS ON. DIAGNOSTIC TROUBLE CODE P2636 WILL BE SET IN THE ENGINE CONTROL MODULE. TECHNICIAN WILL USE NORMAL SERVICE INFORMATION DIAGNOSTICS FOR THE CONCERN. TECHNICIAN WILL OPERATE THE TRANSFER PUMP FOR 2 MINUTES AND MEASURE THE FUEL IN A CONTAINER. THERE SHOULD BE GREATER THAN 2.6 LITERS (0.70 GALLONS) OF FUEL. IF TRANSFER PUMP NOT TO MEET THE FLOW SPECIFICATIONS CHECK FOR PLUGGED FUEL TANK VENTS, KINKED FUEL LINES, A FAULTY TRANSFER PUMP, NO FUEL IN THE REAR TANK, AND LOW VOLTAGE DUE WIRING CONCERN. AFTER PERFORMING NORMAL SI SERVICE INFORMATION DIAGNOSTICS FOR THE CONCERN AND ANOTHER ROOT CAUSE IS NOT FOUND, GENERAL MOTORS ENGINEERING IS AWARE OF THIS CONCERN AND IS WORKING ON A CORRECTION.