2011 Silverado 1500 5.3 Evap valve question
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2011 Silverado 1500 5.3 Evap valve question
Hi everyone, long time lurker hoping someone can point me in the right direction. My Silverado has the P0449 code for the second time. Last winter I got it and ended up replacing the gas cap, purge valve, purge solenoid, tank pressure sensor and vent canister. This Got rid of the CEL until a few weeks ago. I pulling and testing the vent valve and figured it had gone bad because I could not get it to operate with 12 volts from the battery. So today, I put a new vent valve on but cannot get the valve to close when connected at the harness. Supplying it with power from the power side of the harness and grounding to the chassis it will pop closed so it seems to be a problem with the switched ground. Testing at the harness with a multimeter and the ignition off I get about 11v on the power side grounded to the chassis and nothing from the switched ground. Using a circuit tester with an incandescent buld I can get it to illuminate with a chassis ground and connection to the power wire. With the ignition on but engine not running I get the same 11 volts at power to chassis and 11 volts with power to the switched ground. However connecting the lighted circuit tester between the power and switched ground will not light up the bulb. This also will not close the vent valve. It's the same circumstances with the engine running but the voltage is closer to 13 volts. Measuring resistance from the ground to the chassis with the ignition off its an open circuit and with it on its around 5 ohms I think (writing this after testing). I also tested continuity of the switched ground wire all the way to the pcm and it seems to be intact. Not really sure where to go from here. Seems like the valve is not getting enough current to open but I really don't know. If anyone has an idea of something else to check please let me know.
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