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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (2 Of 5)) >> Diagnostic Information and Procedures >> DTC P0476 or P048A >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Ignition - On/Vehicle - In Service Mode
  2. Verify there are no DTCs set, except DTC P0476, P048A, P2B97, related to the following system/component: M122 Exhaust Pressure Regulator Valve
    • Go to next step: If a related DTC is not set 
  3. Ignition/Vehicle - Off - For 30 s
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify the following scan tool parameters are within the specified range:
    • Exhaust Pressure Regulator Valve Learned Closed Position = 6.0 to 14.5%
    • Exhaust Pressure Regulator Valve Learned Open Position = 73 to 93%
    • If not in the specified range 
    1. Ignition/Vehicle - Off
    2. Remove the component: M122 Exhaust Pressure Regulator Valve
    3. Verify a condition does not exist with the component: Blade & Bore@M122 Exhaust Pressure Regulator Valve - Blocked/Casting Flash/Coking/Debris/Dirty/Visible Damage
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no conditions exist
    4. Perform the following action: Rotate - Blade @M122 Exhaust Pressure Regulator Valve

      Verify the following conditions do not exist:

      • Binding or Sticking @ Open/Closed - Position
      • Open/Close - Without spring pressure
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no conditions exist
    5. Replace the component: M122 Exhaust Pressure Regulator Valve
    • Go to next step: If in the specified range 
  6. Perform the scan tool control function: Exhaust Pressure Regulator Valve - Command the component to the minimum position/speed & Maximum position/speed

    Verify the scan tool parameter: Desired Exhaust Pressure Regulator Valve Position = Exhaust Pressure Regulator Valve Position - Through the entire range

    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Remove the component: M122 Exhaust Pressure Regulator Valve
    3. Verify a condition does not exist with the component: Blade & Bore@M122 Exhaust Pressure Regulator Valve - Blocked/Casting Flash/Coking/Debris/Dirty/Visible Damage
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no conditions exist
    4. Perform the following action: Rotate - Blade @M122 Exhaust Pressure Regulator Valve

      Verify the following conditions do not exist:

      • Binding or Sticking @ Open/Closed - Position
      • Open/Close - Without spring pressure
      • If a condition exists - Repair or replace as necessary
      • Go to next step: If no conditions exist
    5. Replace the component: M122 Exhaust Pressure Regulator Valve
    • Go to next step: If the specified state 
  7. 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 

      Repeat the procedure starting at step 1

    • Go to next step: If the DTC does not set 
  8. All OK.
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