So I have been fighting the P1441 issue on my son's 2000 4.3 blazer. I have gone through all the usual suspects,

Replaced the Purge Solenoid
Replace the Vent Solenoid
Replaced the Fuel tank sending unit including the tank pressure sensor.

all to no avail.

My understanding of the code is that the tank sensor is detecting vacuum in the fuel tank while the purge solenoid is supposed to be closed. Typically a purge solenoid is stuck in the open (or flowing) position.

After replacing all the parts I decided to look at this electrically and what I found was interesting. I disconnected the electrical connector from the solenoid and put a noid light on the connector so I could see if the driver is working correctly. As soon as I turn on the Key the light comes on hard and stays on. When I start the car it still stays on. After about 3 or 4 minutes the light starts to dim slowly until it eventually goes out about a minute later.

Now from what i have been able to learn it is my understanding that the solenoid should not turn on until the motor is warmed up and under load. and it should never be open while starting. Question 1: I guess my first question is is this a correct understanding of how the driver should work?

The other thing I am assuming is that the solenoid driver should not fade from a solid ground to open. When operating properly I would assume that the driver would PWM (pulse) the solenoid at a rate that would allow the solenoid to turn on and off a few times per second. Not just fade to a point where it would shut off. Question 2: is that a correct assumption?

In further diagnosing the issue I tried the EVAP test function found in my Autel scan tool. When I run the test I can hear the vent solenoid opening and closing but nothing happens on the Purge Solenoid. it just stays on hard according to the noid light. Question 3: shouldn't the purge solenoid open and close as well during this test?

Unfortunately my OBD2 scanner will not allow me to individually control the EVAP solenoids so that I can test them properly. Question 4: Can any one recommend a OBD tool that will allow me to control the EVAP solenoids directly?

Lastly it would seem from my debugging that it looks like my driver circuit is either shorted to ground or the driver circuit its self is faulty from the ECM. Question 5: Is there a place where this harness would typically get shorted?

If it is the driver then I think I am looking at a new ECM. Question 6: if this is the ultimate cause what is the procedure to replace that? I am reading that it would need to be programmed.

Any help for some or all of these questions will be greatly appreciated.

Thank you in advance.