Engine Controls - System & Component Tests - CNG: Introduction

Before testing separate components or systems, perform BASIC DIAGNOSTIC PROCEDURES in appropriate article:

For Pickup, see BASIC TESTING - 5.4L.
For Van, see BASIC TESTING - 5.4L.

Since many computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction, also perform SELF-DIAGNOSTICS in appropriate article:

For Pickup, see TESTS W/CODES - 5.4L CNG.
For Van, see TESTS W/CODES - 5.4L CNG.

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

NOTE: For identification of circuits and terminals referenced in test procedures, see appropriate article: for Pickup, see WIRING DIAGRAMS - 5.4L CNG; for Van, see WIRING DIAGRAMS - 5.4L CNG.