Anyone know what would happen if the PCV check valve failed?
What would be the systoms?

alot of blow by and may shoot your dip stick out motor may smoke when in high rpm/boost.

alot of blow by and may shoot your dip stick out motor may smoke when in high rpm/boost.
Looks like mine is working properly then. No smoke show here!

You can test it if you are worried or as part of periodic maintenance.

STS - '99 -'04 Chevy Truck Instruction Manual

46. ELECTRICAL SYSTEM TESTS: With the engine running , use a jumper wire to jump across the terminals of the Pressure Switch near the throttle body. You should hear the oil pump get louder and be able to feel the PCV Switch Valve click. Next jumper across the Pressure Switch terminals on the oil pump inlet. This should cause the buzzer alarm to sound inside the cab.

:)

You can test it if you are worried or as part of periodic maintenance.

STS - '99 -'04 Chevy Truck Instruction Manual

46. ELECTRICAL SYSTEM TESTS: With the engine running , use a jumper wire to jump across the terminals of the Pressure Switch near the throttle body. You should hear the oil pump get louder and be able to feel the PCV Switch Valve click. Next jumper across the Pressure Switch terminals on the oil pump inlet. This should cause the buzzer alarm to sound inside the cab.

:)
Sound easy enough, I'll have to give it a try on my lunch.
Thanks Jim.
Tim