K 1500 Yukon Denali AWD V8-6.0L VIN U (2002)
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Running out of fuel
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Fuel fouled spark plugs
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Basic engine fault
Fuel Trim System Operation
The fuel trim system monitors the averages of short-term and long-term fuel trim values. If these fuel trim values stay at the individual limits for a
calibrated period of time, a malfunction is indicated. The fuel trim diagnostic compares the average of short and long-term fuel trim values. If either
value is within the thresholds, a pass is recorded. If either value is outside the thresholds, a rich or lean fuel trim DTC will set.
Comprehensive Component Monitor Diagnostic
Comprehensive component monitoring diagnostics are required to monitor emissions-related input and output powertrain components.
Input Components
The PCM monitors the input components for circuit continuity and out-of-range values. This includes performance checking. Performance checking
refers to indicating a fault when the signal from a sensor does not seem reasonable, such as a Throttle Position (TP) sensor that indicates high throttle
position at low engine loads or manifold Absolute Pressure (MAP) Voltage. The input components may include, but are not limited to, the following
sensors:
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The Vehicle Speed (VSS) Sensor
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The Mass Air Flow (MAF) Sensor
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The Intake Air Temperature (IAT) Sensor
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The Crankshaft Position (CKP) Sensor
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The Knock Sensor (KS)
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The Throttle Position (TP) Sensor
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The Engine Coolant Temperature (ECT) Sensor
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The Camshaft Position (CMP) Sensor
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The Manifold Absolute Pressure (MAP) Sensor
In addition to the circuit continuity and rationality check, the engine coolant temperature (ECT) sensor is monitored for the sensors ability to achieve a
steady state temperature to enable Closed Loop fuel control.
Output Components
Diagnose the output components for the proper response to PCM commands. Components where functional monitoring is not feasible will be
monitored for circuit continuity and out-of-range values if applicable.
Output components to be monitored include, but are not limited to, the following circuits:
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The Idle Air Control (IAC) Motor
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The Evaporative Emission (EVAP) System
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The electronic transmission controls
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The A/C relay, if equipped
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The VSS output
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The Malfunction Indicator Lamp (MIL) Control
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The cruise control enable, if equipped
