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Home >> Cadillac >> 2021 >> CT5 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (Engine Controls And Fuel - 3.0L (LGY) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P026E, P10BA, P1384, P2B83, P2B84, P30AE, P30AF, U02A9, or U05AA >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: M10 Charge Air Cooler Coolant Pump
  3. Test for less than 5 Ω between the test points: Ground terminal 2 & Ground
    • If greater than 5 Ω 
    1. Disconnect the ground connection: Chassis Ground
    2. Test for less than 2 Ω between the test points: Ground terminal 2 Component harness & The other end of the circuit @ Ground Connection
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 5 Ω 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: B+ circuit terminal 1 & 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 Ω between the test points: B+ circuit terminal 1 & Output terminal @ Fuse
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal 1 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M10 Charge Air Cooler Coolant Pump
    • Go to next step: If the test lamp turns On 
  6. Verify a test lamp turns On between the test points: Ignition circuit terminal 5 & 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 Ω between the test points: Ignition circuit terminal 5 & Output terminal @ Fuse
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Replace the component: Fuse
    3. Ignition - On / Vehicle - In Service Mode
    4. 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 6.1
      • 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, except the following component: K20 Engine Control Module
    5. Ignition/Vehicle - Off
    6. Connect the electrical connector: K20 Engine Control Module
    7. Replace the component: Fuse
    8. Ignition - On / Vehicle - In Service Mode
    9. Verify the fuse does not open.
      • If the fuse is open - Replace the component: K20 Engine Control Module
      • Go to next step: If the fuse does not open.
      10. NOTE:

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

    10. 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.
    11. All OK.
    • Go to next step: If the test lamp turns On 
  7. Test for 8 to 10 V between the test points: Serial Data circuit terminal 3 @ Component harness & Ground
    • Go to next step: If less than 8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Serial Data circuit terminal 3 @ 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 Ω between the test points: Serial Data circuit terminal 3 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Replace the component: K20 Engine Control Module
    • If greater than 10 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Serial Data circuit terminal 3 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If between 8 and 10 V 
  8. Replace the component: M10 Charge Air Cooler Coolant Pump
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