GM 4.2L Index of Articles
Ignition System Wiring Diagram (2002-2005 4.2L Chevrolet TrailBlazer)
- February 06, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

The following simplified ignition system wiring diagrams include the coil-on-plug (COP) ignition coils, camshaft position sensor, crankshaft position sensor, and the knock sensor circuits. Applies to the 2002, 2003, 2004, 2005 4.2L Chevrolet... read more >>
How To Test The Ignition Coils (2002-2005 4.2L Chevrolet TrailBlazer)
- February 04, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 coils, to find out if you have a defective one, isn't hard and I'll explain how... read more >>
How To Test The MAP Sensor (2002-2007 4.2L Chevrolet Trailblazer)
- January 20, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 vacuum pump and a multimeter. Now if you don't have a vacuum pump, don't... read more >>
TAC System Wiring Diagram (2006-2007 4.2L Chevrolet TrailBlazer)
- January 24, 2019
- Updated: January 30, 2020
- Written by: Abraham Torres-Arredondo

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 includes the electronic throttle body circuit diagram and the APP sensor... read more >>
How To Test APP Sensor 1 And 2 (2002-2003 4.2L Chevrolet TrailBlazer)
- January 19, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 resistance between two terminals as the pedal is depressed and... read more >>
Camshaft Position Actuator Solenoid Test (2002-2009 4.2L Chevrolet TrailBlazer)
- January 22, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 through 2009 4.2L Chevrolet TrailBlazer and GMC Envoy. With your test... read more >>
Electronic Throttle Body Tests (2002-2007 4.2L Chevrolet TrailBlazer)
- January 18, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 is defective or not. We'll also test the throttle actuator motor. You... read more >>
How To Test Camshaft Position Sensor (2002-2005 4.2L Chevrolet Trailblazer)
- January 22, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 mode. With your multimeter test results will be able to accurately... read more >>
TAC System Wiring Diagram (2002-2005 4.2L Chevrolet TrailBlazer)
- January 18, 2019
- Updated: August 07, 2020
- Written by: Abraham Torres-Arredondo

Here's a simplified throttle actuator control (TAC) system wiring diagram. Includes the electronic throttle body circuit diagram and the APP sensor assembly circuit diagram. Contents of this tutorial: DIAGRAM 1: Electronic... read more >>
How To Test APP Sensor 1 And 2 (2004-2007 4.2L Chevrolet TrailBlazer)
- January 21, 2019
- Updated: July 11, 2020
- Written by: Abraham Torres-Arredondo

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 tutorial I will explain how to do it in a step-by-step way so that you can find... read more >>