05 tahoe in difficulty

[shaft]

hello all, my 05 tahoe has an engine light p0446.
the purge solenoid, the canister, the solenoid on admission, pipe and tank cap were changed, but the light always comes back after a week.
any of you can help me resourare this problem somewhat disquieting :sad72::sad72::sad72:????
thank you to you
shaft

 

[MO Viet Vet]

Evap vent valve has only one purpose. It closes in order to seal the vent so the EVAP system can pressurize and ensure there are no leaks. Evap vent valve is usually supplied Batt. voltage with key on.




The ECM's driver controls the ground, and when grounded, activates the valve (closing it). If the ECM detects a short to ground, and open,or a short to battery voltage on the control circuit, P0446 will set. Code also may refer to ECM detecting that EVAP system is unable to achieve or maintain vacuum during test.

Symptoms

There will be no obvious symptoms to driver, other than Malfunction Indicator Lamp (MIL) illumination.

Causes

A code P0446 could mean one or more of the following has happened:
•Faulty vent valve
•Open, short or excessive resistance on Vent valve control circuit
•Blockage of vent valve
•Bad PCM

Possible Solutions

With a P0446 OBD-II trouble code, here are some things to try:
•Replace Vent valve
•Repair open, short, or resistance problem in control circuit
•Repair open, or short, or resistance problem in power circuit
•Replace PCM

 

[shaft]

thank you for having responded to the pcm that it must be reprogrammed, it is not already programmed to buy ???? tension was tested 13.8v valve and solenoid.the circuit has been tested open, and it works fine.
the solenoid draws well, even the engine running light.

 

[MO Viet Vet]

Your existing PCM should not have to be reprogrammed if just doing repairs unless there is a glitch in it. The list said replace PCM-maybe and if need to then would need to be programmed for your rig.

 

[shaft]

the problem is that I have to change everything and that failure is always present. I do not know what to look for to find the fault.

 

[MO Viet Vet]

I looked at your replacement list and the PCM is not included. I am not saying to replace it but you may need to go back and double check your work, make sure any lines that attach are not pinched down the line from the plug in at a new part, make sure electrical connections are clean and tight and then if cannot find the problem then may need a qualified tech to get involved.

 

[shaft]

ok thank you I'm going to check again and I will keep you posted.
thank you very much for your help
best regards
shaft

 

[MO Viet Vet]

Keep us posted on what happens. There is a guy on here, lesterl, that may be getting off work soon that will look at this and help, also. He is sharp and can shed some light I am sure.

 

[shaft]

hello, I have returned after you test the entire system and everything works fine.
is what it could be from the fuel preesion sensor or pump caurburant it has even ???
thank you to you
best regards
shaft

 

[MO Viet Vet]

Sorry but I did not understand a bit of what you just said.

 

[shaft]

Sorry but I did not understand a bit of what you just said.

sorry I wrote too fast.
I said, after testing you m have said, everything works fine, but the engine light always comes back.
is what the problem could come from the fuel pressure sensor or fuel pump ????
best regards
shaft

 

[MO Viet Vet]

Look for problems with the wiring of the circuitry. Sorry I have no schematic but someone may have one here.

 

[shaft]

hello all, I return to you to tell you that my problem is solved.
it was the fuel vapor pressure sensor located on the fuel pump in the tank that was breaking.
the pressure sensor does not give the info to pcm. suddenly the pcm could not say the purge solenoid opens to.

thank you to you for your help. Your forum is a real gold mine for me.
sincerely shaft