GM 4.2L Index of Articles

The following simplified ignition system wiring diagrams include the coil-on-plug (COP) ignition coils, camshaft position sensor, crankshaft position sensor, and the knock... [read more]

In this tutorial I'm going to explain how to test the ignition coils on the 2002, 2003, 2004, and 2005 4.2L Chevrolet TrailBlazer and GMC Envoy. Testing the ignition... [read more]

This tutorial will help you to test the manifold absolute pressure (MAP) sensor on the 2002-2007 4.2L Chevrolet TrailBlazer or GMC Envoy. All you'll need to test it is a... [read more]

The throttle actuator control (TAC) system is made up of the following: APP Sensor 1, APP Sensor 2, TPS 1, TPS 2, Throttle Actuator Motor. This simplified wiring diagram... [read more]

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]

In this tutorial I'm going to be showing you how to test the camshaft position actuator solenoid. The exact same camshaft position actuator solenoid is used on the 2002... [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... [read more]

In this tutorial I'm going to show you how to test the camshaft position sensor, on the 2002-2005 4.2L Chevrolet TrailBlazer and GMC Envoy, using a multimeter in Volts DC... [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 APP sensor 1 and APP sensor 2 on the 2004-2007 4.2L Chevrolet TrailBlazer or GMC Envoy is something that can be done easily with just a multimeter. In this... [read more]