GM 4.2L Index of Articles

In this tutorial, I'm going to explain how to test accelerator pedal position (APP) sensor 1 and sensor 2. Testing both of these APP sensors simply involves testing the... [read more]

This tutorial will explain how to test the electronic throttle body on the 2002-2007 4.2L Chevrolet TrailBlazer and GMC Envoy. You'll be able to find out if TPS 1 or TPS 2... [read more]

In this tutorial, I'm going to show you how to test the engine compression on the 4.2L equipped 2002-2009 Chevrolet TrailBlazer or GMC Envoy. The engine compression test... [read more]

Here's a simplified throttle actuator control (TAC) system wiring diagram. Includes the electronic throttle body circuit diagram and the APP sensor assembly circuit... [read more]

Testing to see if your 4.2L Chevy Trailblazer or 4.2L GMC Envoy has a blown head gasket is not difficult at all. In this tutorial, I'm gonna' explain the four most common... [read more]

The spark plugs on your 4.2L Chevrolet TrailBlazer or GMC Envoy are designed to last a very long time. But as the engine wears and it accumulates lots of miles, you're... [read more]