Engine Controls - System & Component Testing - 7.3L Diesel: Introduction

WARNING: Ensure negative battery cables are disconnected before disconnecting engine wiring harness. The Injector Driver Module (IDM) supplies 115-volts DC into each fuel injector connected to engine wiring harness. Severe electrical shock hazard exists. DO NOT pierce wires.

Since many computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction, perform QUICK TEST in TESTS W/CODES - 7.3L DIESEL article. Service DTCs as necessary.

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.