Hello Everyone, I hope this helps as my issue was repaired.
It was after reading these posts that I finally took my 2019 Silverado Trail Boss into service. Starting back in May of 2021 my Trail Boss at around 11,000 miles would fail to start without pressing the startup button 3-4 times in a row and pumping the gas. The truck would act as though it was going to start, the gauges would all cycle, then the truck would hesitate for a second then shut off. At this same time, my Check Engine Light started coming on as well.
What was different about my experience from any that I have read here, was the truck would consistently start EXCEPT immediately after refuelling. So basically I would go to gas up, then be stuck at the gas station trying to turn the vehichle on. In between fuelings, the truck never failed to start.
I took it to the dealer to be serviced and they fixed it, eventhough they said they had never heard of this kind of issue before. It has been 3 fuelings since I had the repair, and the truck has never hesitated to start.
According to the service receipt/work order, here is what they found:
Confirmed Customer Concern of Check Engine Light Is On. Scanned for codes and found in ECM: P0443-00 EVAP Purge solenoid valve control circuit, P0458-00 EVAP purge solendoid valve control circuit low voltage, monitored EVAP data with engine at idle and no control of functions and found Fuel Tank Pressure Sensore (FTPS) was reading -9.0 to -10.0 in H20 of Vacuum. Commanded EVAP system sealed and confirmed engine stalled due to excessive vacuum on system in excess of -15 in H20 immediately.
Disconnected purge solenoid vavle electrical connector and tested circuits, confirmed test lamp illuminated on voltage circuit. Found test lamp illuminated when connected to low reference or contro side of circuits from ECM, indicating short to ground on control circuit which will hold to purge valve open thus causing concerns.
Measured 12.7 ohms to ground on low ref control circuit, disconnected ECM connector X1 and found short to group was no longer present. Measured circuit end to end and measured .2 ohms and passing. Inspected harness and found no signs of damage to any wires, reconnected ECM and found short to ground returned. Confirmed concern is an internal short to ground on the purge valve control circuit. Recommend replacling Engine Control Modue (ECM) to correct concerns.
Replaced ECM as per diagnostics. Performed prepare control module.
