Engine Controls - System/Component Tests: Introduction

Before testing separate components or systems, perform procedures in BASIC TESTING article. Since the introduction of OBD-II, most all computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction. Information for these components is covered in DIAGNOSTIC TESTS in appropriate TESTS W/CODES article below:

For I30 see TESTS W/CODES
For Q45 see TESTS W/CODES

NOTE: Testing individual components does not isolate a short or open circuit. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.