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Home >> Chevrolet >> 2022 >> Tahoe PPV, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (5 Of 5)) >> Diagnostic Information and Procedures >> DTC P26C0, P26C2, P29FA, P29FB, U0618, or U111A >> 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: Q97B Engine Coolant Flow Control Valve - Block
  3. Test for less than 10 ohms between the test points: Ground terminal 2 & Ground
    • If greater than 10 ohms 
    1. Disconnect the ground connection: G176A
    2. Test for less than 2 ohms between the test points: Ground terminal 2 @ Component harness & G176A
      • 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 @ F88UA 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: Ignition circuit terminal 3 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: Q97B Engine Coolant Flow Control Valve - Block
    • Go to next step: If the test lamp turns On 
  6. Test for 8 to 10 V between the test points: Serial Data circuit terminal 1 @ Component harness & Ground
    • 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 1 @ 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 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 1 @ 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: Serial Data circuit terminal 1 @ Component harness & Terminal 105 X2 @ 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 between 8 and 10 V 
  7. Test or replace the component: Q97B Engine Coolant Flow Control Valve - Block
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