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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (5 Of 5)) >> Diagnostic Information and Procedures >> DTC P2564, P2565, or U0656 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
    NOTE:
    • Disconnecting the component electrical connector causes additional DTCs to set.
    • 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 electrical connector: M103 Turbocharger Vane Position Actuator
  3. Test for less than 5 ohms between the test points: Low Reference circuit terminal 3 & Ground
    • If 5 ohms or greater 
    1. Disconnect the appropriate electrical connector: K20 Engine Control Module
    2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 3 @ 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
    • Go to next step: If less than 5 ohms 
  4. Ignition - On/Vehicle - In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 4 & Low Reference circuit terminal 3
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: 5 V Reference 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: 5 V Reference 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: K20 Engine Control Module
    • If greater than 5.2 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: 5 V Reference 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: K20 Engine Control Module
    • Go to next step: If between 4.8 and 5.2 V 
  6. Test for 4.8 to 5.2 V between the test points: Serial Data circuit terminal 2@Component harness & Ground
    • If less than 4.8 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 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 infinite resistance between the test points: Serial Data circuit terminal 2@Component harness & Low Reference circuit terminal 3@Component harness
      • If less than infinite resistance - Repair the short between the circuits.
      • Go to next step: If infinite resistance
    5. Test for less than 2 ohms between the test points: Serial Data 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: K20 Engine Control Module
    • If greater than 5.2 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 2@Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If between 4.8 and 5.2 V 
  7. Test or replace the component: M103 Turbocharger Vane Position Actuator