04 Full Size Trucks and Utilities with VIN G , N , T, V and U Engines May Have a High Altitude, High Ambient Temperature Stall - kw L18 LM7 LQ4 LQ9 LR4 crank DTC fuel hard Hesitate idle

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Some 2004 Full Size Trucks and Utilities with VIN G, N, T, V and U engines that were built prior to May 1st, 2004, may stall while driving. Typically, this will occur when the altitude exceeds approximently 5,000 feet above sea level with an ambient temperature of 80 degrees F or greater. The vehicle may set DTCs P0171 and P0174 and exhibit a crank no start, hard start, lack of power or rough running concern until the vehicle cools down.

This PI does not apply to vehicles with the L59 (Vin Z) 5.3L engine. Monitor the fuel pressure during the concern. If this PI applies, the fuel pressure will be lower than specification during the concern. If the fuel pressure is low, perform the SI fuel system diagnosis during the concern. If the SI diagnostics isolate a fuel pump module concern, there is an updated fuel pump module available to address this concern. Specific part numbers may be assigned to these updated fuel pump modules in the future. For right now, if the current part number from the parts catalog has a date code of 0834 or newer, it is the updated fuel pump module and should be installed. It may be necessary to open a SPAC case to obtain one of these fuel pump modules.

Note: The Fuel Pump Module Date Code will be on top of the fuel pump module, just below the bar code and production part number. The date code will be a 4 digit number with the first 3 digits being the day of the year and the 4th digit being the year. So a date code of 0834 would translate to the 83rd day of 2004.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

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