Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The scan tool first energizes the following components for a precise amount of time allowing a measured amount of fuel into the manifold:
- High pressure lock off (HPL)
- Low pressure lock off (LPL)
- CNG fuel injectors
This causes a drop in system fuel pressure that can be recorded and used to compare each fuel injector.