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Tahoe / Yukon Service Manual

DTC P0300-P0306

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5135944 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P0300 Engine Misfire Detected DTC P0301 Cylinder 1 Misfire Detected DTC P0302 Cylinder 2 Misfire Detected DTC P0303 Cylinder 3 Misfire Detected DTC P0304 Cylinder 4 Misfire Detected DTC P0305 Cylinder 5 Misfire Detected DTC P0306 Cylinder 6 Misfire Detected Circuit/System Description For an overview of the component/system, refer to: Fuel System Description A misfiring cylinder causes slight variations in the rotational speed of the crankshaft. The engine control module (ECM) is able to detect these variations by closely monitoring the crankshaft position sensor signal. The signals of the camshaft position sensors are used to determine which cylinder is misfiring. If the ECM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, a misfire DTC will set. Conditions for Running the DTC DTC P0016, P0101–P0103, P0106–P0108, P0111–P0114, P0117–P0119, P0191–P0193, P0335, P0336, P0340, P0341, P0601, P0604, P0606, P0641, P0651, P16A0– P16A2, P16F3, P2227–P2230 = Not set Crankshaft/Camshaft Sensors = Synchronized Engine Coolant Temperature = −9 to 127°C (15.8 to 260.6°F) Engine Speed = Greater than 1,000 RPM — DTC P0315 is set. Engine Speed = 550 to 8,191 RPM Fuel Cut-Off System = Inactive Rough Road Signal = Not Detected System Voltage = 9 to 32 V Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC The control module K20 detects a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards. Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Diagnostic Aids High resistance in the circuits of the component may set DTC P0300 without setting the DTC for the component: Q17 Fuel Injector If the condition is intermittent, wiggle the related wiring harnesses and connectors, with the ignition/vehicle on or engine running, while monitoring the scan tool circuit status parameters for the component. The parameters will display if there is a condition with the circuit or a connection. The following conditions could cause DTC P0300 to set: – Accessory drive bracket — Defective / Loose / Visible Damage – Belt Driven Device — Defective / Loose / Visible Damage – Brake Rotor — Excessive runout – Component Malfunction — Transmission – Drive Belt — Defective / Loose / Visible Damage – Drive Shaft — Excessive runout – During certain road conditions: Rough Tire and wheel assemblies which exhibit excessive runout can produce vibrations even if the assemblies are balanced. Reference Information Description and Operation Fuel System Description DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Engine » Idling
  2. Verify there is no abnormal noise from the component: Engine ⇒ If an abnormal noise is present Refer to: Symptoms - Engine Mechanical ⇓ If no abnormal noise is present
  3. Perform the scan tool learn/reset function: Crankshaft Position Variation Learn
  4. Verify there are no DTCs set related to the following component/system: B23 Camshaft Position Sensor B26 Crankshaft Position Sensor E12 Glow Plug Q17 Fuel Injector Fuel System Mechanical Condition ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  5. Verify the scan tool parameter: Cylinder 1–6 Current Misfire Counter = Does not Increment ⇒ If the parameter value increments Refer to: Circuit/System Testing ⇓ If the parameter value does not increment
  1. Perform the scan tool control function: Cylinder Power Balance » Enable Verify the engine speed or sound changes the same way when turning off each fuel injector. ⇒ If the engine sound does not change the same way for one or more cylinders Refer to: Circuit/System Testing ⇓ If the engine sound changes the same way for all cylinders
  2. Verify the scan tool parameter: Cylinder 1–6 Current Misfire Counter = Does not Increment Perform the action while monitoring the parameter: Wiggle the harness and connector: K20 Engine Control Module Wiggle the harness and connector: Q17 Fuel Injector ⇒ If not the specified state Repair or replace as necessary ⇓ If the specified state
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC does not set
  4. All OK. Circuit/System Testing
  5. Ignition/Vehicle » Off
  6. Verify the tool is available: CH-51450-A Oscilloscope Diagnostic Kit & CH-51450-LEAD-A Oscilloscope Basic Lead Kit ⇒ If the tool is not available Refer to step 4 ⇓ If the tool is available
  7. Perform the following procedure/test: Relative Engine Compression Test Verify the procedure/test passes. ⇒ If the procedure/test does not pass Refer to: Symptoms - Engine Mechanical ⇓ If the procedure/test passes
  8. Verify the following conditions do not exist: Q17 Fuel Injector — Incorrect connection / Leaking / Loose / Visible Damage Fuel — Fill Level = Low Fuel Line (All ) — Blocked / Incorrect connection / Kinked / Leaking / Loose / Visible Damage ⇒ If a condition exists Repair or replace as necessary ⇓ If no conditions exist
  9. Perform the following procedure/test: Fuel System Diagnosis ⇒ If the procedure/test does not pass Repair or replace as necessary ⇓ If the procedure/test passes
  10. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification High Pressure Diesel Fuel Injector Replacement