Chasing a gremlin
looking for electronic diagrams for 07 Avalanche
Evac system error but valve is okay
Intermittent oil pressure gauge error
Stabilitrac and Traction control error
Truck stuck in limp mode

 

Evac...What system is that?
there are over 200 diagrams...be specific
post the codes that are set.

 

449 evap solenoid vent valve
and
641 sens A voltage circuit open/reference voltage circuit open

 

vent solenoid code
find the vent solenoid...it will have a 2 wire connector. disconnect it.
one wire is supplied battery voltage at key on
one wire is grounded by the pcm when the pcm commands the vent closed.
to test
check for battery voltage on the one wire.
reinstall the connector...jumper the other wire to grd….the solenoid should close and make a click sound...when the grd is removed the solenoid should release and click. if you hear nothing, replace the solenoid. if the solenoid works... either the grd wire to the pcm is open or the pcm is not commanding grd

the other code is a p code or body chassis or undefirned u code? p0641? p1641 p2641

 

The cable has power but ground is open somewhere.
It is a P0641. code
Is there any relationship to the intermittent oil sensor fault