Diagnostic Aids

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Monitoring Fuel Injector circuit status with scan tool, while moving fuel injector harness, may help isolate an intermittent condition.
Performing Fuel Injector Coil test may help isolate an intermittent condition. See FUEL INJECTOR COIL TEST .
For an intermittent condition, go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.