2015 GMC Sierra 1500
Mileage
142,916
Service Date
7/10/2024
Services Performed
- Recovered system, found 1.26 lbs recovered, system held vacuum during vacuum test. Recharged system and found old air does not blow out of passenger vents but does from driver vents. Monitoring scan data, found temperature control door on passenger side lowest value is higher than the driver side. Blend door seems to move normally. Performed blend door calibration to reset minimum and maximum movement of each temperature control door. Found after performing calibration, both minimum values for the temperature control doors matched (driver and passenger). Operating a/c system found that both side vents blow cold air, system operates normally. There may be a mechanical problem that causes passenger side temperature control door to get stuck before moving all the way to cold if problem occurs again.
- Found code P128- ECT (engine coolant temperature) below thermostat regulating temperature, found vehicle does not operate at thermostat regulating temperature after running, no discrepancy between ECT and actual temperature. Thermostat most likely sticking open, replacement required. Cooling fans will default on high and A/C may shut off when this fault occurs. Found codes P0172 and P0175 both banks too rich. Ran vehicle while monitoring live data and found fuel trims were cutting fuel at idle. Found TSB (technical service bulletin) for a diagnostic tip on both codes that are present stating that it is possible for the high pressure fuel pump to leak fuel into the crankcase, causing a rich condition when the PCV system pulls the fuel mist into the intake. Pulled oil dipstick and oil cap and found a strong odor of fuel in the crankcase/oil. With engine running, pulled and capped off the PCV vacuum hose at the intake and found the fuel trims returned to normal. Based on the testing the high pressure fuel pump is leaking into the crankcase and will need to be replaced to fix this concern.
- Perform a 28 point inspection
- Depressurized fuel system. Removed air cleaner tube, removed throttle body, removed harness clips from intake manifold cover, removed intake manifold and cover. Removed low and high pressure fuel feed lines, removed old high pressure fuel pump. Replaced high pressure fuel pump with new gasket and hardware. Replaced high pressure fuel supply and crossover lines with new lines and hardware. Reinstalled components with new intake gaskets. Primed fuel system and started vehicle, monitored live data and verified that fuel trims were now within specifications and engine runs smooth, trouble codes did not return.
- Drained engine coolant, removed intake tube, removed radiator hose from thermostat housing, removed and replaced thermostat with a new unit.
- SERVICE SPECIAL – 5 QUARTS OF OIL, FILTER AND 28 POINT VEHICLE INSPECTION.
- Performed transmission flush with 16qts of Lucas ATF. Test drove vehicle to confirm transmission shifts properly.
GORDON H. gave our service a 5 star review on 7/10/2024
