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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 47 (Exhaust System) >> Diagnostic Information and Procedures >> DTC P26C5-P26C7 or P31CF-P31E8 (L3B) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Test 1

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the appropriate electrical connector:
    • {Right Side} M106S Exhaust Control Valve Actuator - Sound Quality
    • {Left Side} M106SB Exhaust Control Valve 2 Actuator - Sound Quality
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 1 & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: Ground terminal
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 1 @ Component harness & The other end of the circuit @ Ground terminal
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: Ignition circuit terminal 3 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points: Ignition circuit terminal 3 & Output terminal @ Fuse
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.

        Or

      • If less than 2 ohms - Refer to: Power Mode Mismatch
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Connect the electrical connector: M106S Exhaust Control Valve Actuator - Sound Quality
    3. Ignition - On / Vehicle - In Service Mode
    4. Replace the component: Fuse
    5. Verify the fuse does not open.
      • If the fuse opens and there are components connected to the circuit - Disconnect a component and repeat procedure starting at step 5.4
      • If the fuse opens with all components disconnected from the circuit - Repair the short to ground on the circuit.
      • If the fuse does not open after disconnecting a component from the circuit - Replace the component disconnected last.
      • Go to next step: If the fuse does not open with all components connected.
      6. NOTE:

      It may be necessary to use a scan tool control function to operate a component.

    6. Operate the component: Each component on the circuit - One at a time

      Verify the fuse does not open when any of the components are activated.

      • If the fuse opens - Replace the component that caused the fuse to open when activated.
      • Go to next step: If the fuse does not open.
    7. All OK.
    • Go to next step: If the test lamp turns On 
  6. Test for 4.8 to 5.2 V between the test points: Signal circuit terminal 4 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Power Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 4 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 4 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K111 Fuel Pump Power Control Module
    • If greater than 5.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Power Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 4 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K111 Fuel Pump Power Control Module
    • Go to next step: If between 4.8 and 5.2 V 
  7. Test for greater than 0.00 V, but less than 5.8 V between the test points: Control circuit terminal 2 & Ground
    • If 0.00 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Power Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Control circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K111 Fuel Pump Power Control Module
    • If greater than 5.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K111 Fuel Pump Power Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 2 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K111 Fuel Pump Power Control Module
    • Go to next step: If greater than 0.00 V and less than 5.8 V 
  8. Swap the two components: M106S Exhaust Control Valve Actuator - Sound Quality - The original component that set the DTC & Another known good component from the vehicle
  9. Clear the DTCs.
  10. 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 sets at the original component location.

    • If the DTC does not set at the original component location 

      Test or replace the component: M106S Exhaust Control Valve Actuator - Sound Quality - The original component that set the DTC

    • Go to next step: If the DTC sets at the original component location 
  11. Replace the component: K111 Fuel Pump Power Control Module

Test 2

  1. Ignition/Vehicle - Off
  2. Verify a condition does not exist with the component: Linkage @ M106S Exhaust Control Valve Actuator - Sound Quality or Valve @ Tail Pipe - Binding or Sticking/Debris/Dirt/Ice or Snow/Interference with other components or objects /Modified/Visible Damage
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no condition exists 
    3. NOTE:

    The learn procedure must be performed if the component has been removed, replaced, or serviced: M106S Exhaust Control Valve Actuator - Sound Quality

  3. Remove the appropriate component:
    • {Right Side} M106S Exhaust Control Valve Actuator - Sound Quality
    • {Left Side} M106SB Exhaust Control Valve 2 Actuator - Sound Quality
  4. Verify the component works as specified: Shaft @ Exhaust Pipe - Rotates freely
    • If the component does not work as specified 
    1. Ignition/Vehicle - Off
    2. Verify a condition does not exist with the component: Valve @ Exhaust Muffler Assembly - Blocked by debris/Casting Flash/Soot Accumulation/Visible Damage
      • If a condition exists - Repair or replace as necessary
      • If no condition exists - Replace the component: Exhaust Muffler Assembly or Tail Pipe
    • Go to next step: If the component works as specified 
  5. Test or replace the component: M106S Exhaust Control Valve Actuator - Sound Quality
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