3rd and final message. These are all separate issues I assume so I am listing them separately. Sorry if I should have done all 3 in 1 message...

I am getting the above codes from Autozone. I am assuming there is a leak somewhere based on them. When I shut the truck off there is a loud "pop" sound like rushing air. Any ideas where I begin to check and test for such an issue? I am not even sure where this EVAP canister is!

The messages say it could be a purge or vent solenoid that is defective, a vacuum leak at the engine, air pump defective or hose blocked...

Thanks yet again!

 

I did some more searching on this forum and found my answers I believe. You have to know what to search on to find what you are looking for!

 

*Moving to the GMT360/370 section* - The 2nd Gen Tech section is for 2nd gen s-series vehicles.

Diagnostic charts for the codes themselves:
P0410 (GMT360/370) - Secondary Air Injection System
P0455 (GMT360/370) - Evaporative Emission Control System Leak Detected (gross leak/no flow)

The P0455 code is likely caused by a malfunctioning EVAP purge solenoid which is located below the intake manifold on the driver side of the engine near the brake booster. It is likely easiest to access through the wheel well. First check to make sure that the vacuum line to the EVAP purge solenoid is properly connected.

The P0410 code could be a result of the drop in voltage you are experiencing in your other thread.