The most valuable reference source is the Service Manual. For 1994, light duty trucks service manuals have been reorganized to make them easier to use. The Driveability and Emissions (Diesel) Service Manual contains all the information necessary for diagnosing fuel and emissions systems.
Driveability and Emissions (Diesel) Service Manual
The Driveability and Emissions manual is organized into the following sections:
• Section 1: General Information
• Section 2: Driveability Symptoms
• Section 3: Control Module System
• Section 4: Fuel System
• Section 7: Glow Plug System
• Section 9: Exhaust Gas Recirculation (EGR) System
• Section 10: Transmission Controls
• 10A: 4L60E Diagnostic Trouble Codes
• 10B: 4L80E Diagnostic Trouble Codes
• Section 11: Crankcase Ventilation System
• Section 12: Air Intake System
• Section 13: Special Tools
• Section 14: Abbreviations and Glossary of Terms
SECTION 3: CONTROL MODULE SYSTEM
Section 3 of the Driveability and Emissions Service Manual contains general as well as detailed information about the engine management system. Component descriptions provide a basic understanding of the role each sensor, switch, soienoid, and relay perform within the system. There are also descriptions of diagnostic modes and strategies.
The aspects of section 3 most vital for diagnosis are the circuit and trouble tree charts (figure 6-1). These are presented as facing-page spreads, with the circuit information on the left and the trouble tree on the right. These pages include:
• a wiring schematic for the components under discussion
• the diagnostic trouble code number and name for the circuits
• a circuit description
• a list of parameters that set the identified code
• a description of the operating mode the PCM defaults to when the code sets as well as conditions under which the code clears from PCM memory
• an explanation of steps used in the trouble tree
