Can Someone tell me what I can do to finally resolve this code on my LT1? I've already replaced the Vacum Switch next to the cannister, check all hoses for leaks, checked charcol cannister for external damage and I even took an air hose to the line that goes from the cannister all the way to the manifold and blew out everything to make sure it was not clogged. I also notice that when I open my gas cap that there is a lot of pressure built up? I'm not sure if that is normal?? Any other tips you guys can give me before I start replacing everything in the EVAP system. Even just a way to test the purge solienoid? Thanks!

 

Use a source of vacuum to apply vaccum to the top port of the EVAP solenoid. You should detect vacuum from the bottom port when the solenoid is operated. You can jumper 12v to the brown wire and ground to the drk grn/wht to operate it or you can put the pcm in field service mode by looping pins 5 and 6 at the DLC and then turn key to ON (not start).

 

Thanks Shoebox.

What would putting the PCM in service mode do? Would this allow me to operate the cylinder by jumping the wires on the solenoid?

 

Oh sorry, I guess I did not explain that putting it in field service mode will operate the solenoid (it and most others). Your fans will probably come on, too.