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Home >> Chevrolet >> 2022 >> Tahoe PPV, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (4 Of 5)) >> Diagnostic Information and Procedures >> DTC P157A or P16D7-P16D9 >> 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: X1 @ K20 Engine Control Module
  3. Remove the component: F80UA Fuse & F60UA Fuse @ X50A Engine Wiring Harness Junction Block
  4. Connect a test lamp between the test points: F80UA Fuse - Input terminal & Ground
  5. Ignition - On / Vehicle - In Service Mode
  6. Momentarily connect a 3 A fused jumper wire between the test points: Control circuit terminal 64 @ Control module harness & B+

    Verify the test lamp does not turn On and Off.

    • If the test lamp turns On and Off 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Test for less than 1 V between the test points: F80UA Fuse - Output terminal & Ground
      • If greater than 1 V - Repair the short to voltage on the circuit:
      • Go to next step: If less than 1 V
    3. Test for less than 1 V between the test points: F60UA Fuse - Output terminal & Ground
      • If greater than 1 V - 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 the test lamp does not turn On and Off 
  7. Ignition/Vehicle - Off & Remove - Jumper wire(s) & Test Lamp
  8. Install the component: F80UA Fuse & F60UA Fuse
  9. Disconnect the electrical connector: X50A Engine Wiring Harness Junction Block
  10. Test for less than 10 ohms between the test points: Ground circuit terminal X1-A4 @ Fuse Block Harness & Ground
    • If greater than 10 ohms 
    1. Disconnect the appropriate ground connection:
      • {Silverado/Sierra} G104
      • {Escalade/Suburban/Tahoe/Yukon} G102A
    2. Test for less than 2 ohms between the test points: Ground circuit terminal X1-A4 @ Fuse Block 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 
  11. Ignition - On / Vehicle - In Service Mode
  12. Test for less than 1 V between the test points: Control circuit terminal 64 @ Control module harness & Ground
    • If 1 V or greater - Repair the short to voltage on the circuit. 
    • Go to next step: If less than 1 V 
  13. Ignition/Vehicle - Off
  14. Test for infinite resistance between the test points: Control circuit terminal 64 @ Control module harness & Ground
    • If less than infinite resistance - Repair the short to ground on the circuit. 
    • Go to next step: If infinite resistance 
  15. Test for less than 2 ohms between the test points: Control circuit terminal 64 @ Control module harness & Terminal X3 - C5 @ Fuse Block Harness
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 ohms 
  16. Test or replace the component: X50A Engine Wiring Harness Junction Block
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