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Tahoe / Yukon Service Manual

DTC P034A or P034B

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5499628 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 P034A Crankshaft Position Sensor - Engine Start Position Incorrect DTC P034B Crankshaft Position Sensor - Crankshaft Direction Incorrect Circuit/System Description The engine control module monitors the speed and the direction of rotation of the crankshaft during an autostop event and memorizes the crankshaft angle at which the engine stopped to be able to start the engine quicker. Conditions for Running the DTC DTC P0335, P0336 = Not set Crankshaft position is being verified. Engine = Running — After an autostop event. Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P034A Condition 1 The difference between the memorized and actual crankshaft position was greater than 1 reluctor ring teeth during 2 autostart events in one ignition cycle. Condition 2 The difference between the memorized and actual crankshaft position was greater than 1 reluctor ring teeth during 4 autostart events in one ignition cycle. P034B The direction of rotation of the crankshaft has changed more than 3 times within 10 s. 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 A DTC may set depending on certain driving conditions and would not require a component replacement. The Circuit/System Verification must be performed. Reference Information DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify DTC P0335, P0336, P0651 is not set. ⇒ If any of the DTCs are set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If none of the DTCs are set
  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 Test or replace the component: B26 Crankshaft Position Sensor ⇓ If the DTC is not set
  4. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Crankshaft Position Sensor Replacement