Diagnostic Aids

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

The tests in this document can be used to find the cause of misfire, knock, excessive smoke or rough running conditions when no relevant DTCs are set.

Fuel Injector Balance

During this test, the injectors are turned off one after the other while the engine is running. The change in engine sound, when an injector is turned off, is an indicator how much power that cylinder contributes. If a cylinder generates less power than the others, that indicates a problem with either the compression or the injector.

Compression Test

This function disables the injectors so that a mechanical compression test can be performed.