Yukon Denali 4WD V8-6.0L Hybrid (2011)
Fuel Injector: Testing and Inspection
Fuel Injector Diagnosis
Diagnostic Instructions
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Perform the Diagnostic System Check - Vehicle See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle prior to using this diagnostic procedure.
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Review Strategy Based Diagnosis See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis for an
overview of the diagnostic approach.
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Diagnostic Procedure Instructions See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure Instructions
provide an overview of each diagnostic category.
Circuit/System Description
The control module enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The
control module controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance
that is too high or too low will affect the engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel
injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector
increases.
When performing the fuel injector balance test, the scan tool is first used to energize the fuel pump relay. The fuel injector tester or the scan tool is then
used to pulse each injector for a precise amount of time, allowing a measured amount of the fuel to be injected. This causes a drop in the system fuel
pressure that can be recorded and used to compare each injector.
Diagnostic Aids
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Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.
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Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
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Perform the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain
temperature, or under certain conditions.
Reference Information
Schematic Reference
Engine Controls Schematics See: Diagrams/Electrical Diagrams/Wiring Schematic Index
Connector End View Reference
Component Connector End Views See: Diagrams/Connector Views/Connector End Views By Name
Electrical Information Reference
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Circuit Testing See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing
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Connector Repairs See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs
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Testing for Intermittent Conditions and Poor Connections See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions See: Computers and Control Systems/Testing and Inspection/Diagnostic Trouble Code
Descriptions/Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References See: Testing and Inspection/Programming and Relearningfor scan tool information
Special Tools
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CH-48027 Digital Pressure Gauge
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J 39021 Fuel Injector Coil and Balance Tester
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J 44602 Injector Test Adapter
Component Testing
Fuel Injector Coil Test
1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description See: Hybrid Drive
Systems/Description and Operation/Hybrid Modes of Operation Description.
