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Home >> Chevrolet >> 2023 >> Tahoe SSV >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (3 Of 5)) >> Diagnostic Information and Procedures >> DTC P066A-P066F, P0671-P0676, or P067A-P067F >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

Test 1

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: X1 @ K20 Engine Control Module
  3. 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 ohms between the test points:
      • {Escalade} B+ circuit terminal 1 & Output terminal @F5UD Fuse
      • {Sierra/Silverado/Tahoe/Yukon} B+ circuit terminal 1 & Output terminal @F5BA 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.
    • 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: K20 Engine Control Module
    • Go to next step: If the test lamp turns On 
  4. Replace the component: K20 Engine Control Module

Test 2

  1. Ignition/Vehicle - Off
  2. Disconnect the appropriate electrical connector: E12 Glow Plug
  3. Ignition - On/Vehicle - In Service Mode
  4. Connect a test lamp between the test points: Control circuit terminal 1/A & Ground
  5. Perform the scan tool control function: Glow Plugs - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: X1@K20 Engine Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 1/A@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 1/A@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: K20 Engine Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: X1@K20 Engine Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 1/A@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 the test lamp turns On and Off 
  6. Test or replace the component: E12 Glow Plug
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