This course reviews the diagnostic procedure, theory, and operation of the General Motors 6.6
Liter Duramax Engine. Common rail diagnosis will be emphasized in this course such as fuel
pressure testing both on the high and low pressure side plus injector testing and fuel injector
control module (FICM) operation. Duramax engine LLY-LBZ and LMM will be discussed. Service
information will be used to aid the technician in vehicle diagnosis. This will be supplemented
with the use of the scan tool in interpreting data and using bidirectional controls that are available.

Duramax Systems Overview
Injector Operation
Fuel system Operation, hi/low pressure systems
Fuel Injector Control Module (FICM)
Turbocharging operation, including variable geometry turbos
After-treatment systems (DPF, NOx/EGR)
Biodiesel issues, Biodiesel blends
Electronic Engine Controls Operation
Diagnostic Strategies
Fault Code determination and diagnosis
PCM input and output
Starting systems
Hard Start, No Start & Performance Diagnostics
Electronic Engine Control Testing
Fuel Charging & Controls
Crankcase Pressure Testing
High Pressure Oil System
Technician Tips:
Repair Procedure
Pattern Failures
Pinpoint Test shortcuts


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