LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2023 >> Tahoe SSV >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (5 Of 5)) >> Diagnostic Information and Procedures >> DTC P2687-P2689 >> 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. Remove the component: KR22 Fuel Heater Relay
  3. Ignition - On/Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points: Ignition circuit terminal 2 & 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 2 @ Relay Socket & Output terminal @ F85UA 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.
    • Go to next step: 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 2 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: KR22 Fuel Heater Relay
    • If the test lamp turns On 
  5. Verify a test lamp does not turn On between the test points: Control circuit terminal 1 & B+
    • If the test lamp turns On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: X2@ K20 Engine Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 1 @ Relay Socket & 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 does not turn On 
  6. Remove - Test Lamp
  7. Perform the scan tool control function: Fuel Heater Relay - On

    Verify the scan tool parameter: Fuel Heater Relay Control Circuit High Voltage Test Status = OK

    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: X2@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 @ Relay Socket & 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 specified state 
  8. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 1 & Ignition circuit terminal 2
  9. Perform the scan tool control function: Fuel Heater Relay - On

    Verify the scan tool parameter: Fuel Heater Relay Control Circuit High Voltage Test Status = Malfunction

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: X2@ K20 Engine Control Module
    3. Test for less than 2 ohms between the test points: Control circuit terminal 1 @ Relay Socket & Terminal 37 @ 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 the specified state 
  10. Verify a test lamp turns On between the test points: B+ 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: B+ circuit terminal 3 @ Relay Socket & Output terminal @ F10UB 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 3 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Disconnect the electrical connector: R29 Fuel Filter
    4. Test for infinite resistance between the test points: Control circuit terminal 5 @ Relay Socket & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    5. Replace the component: F10UB Fuse
    6. Install the component: KR22 Fuel Heater Relay
    7. Connect a test lamp between the test points: Control circuit terminal 2 & Ground circuit terminal 1
    8. Ignition - On/Vehicle - In Service Mode
    9. Perform the scan tool control function: Fuel Heater Relay - On and Off

      Verify the test lamp turns On and Off.

      • If the test lamp does not turn On and Off - Test or replace the component: KR22 Fuel Heater Relay
      • If the test lamp turns On and Off - Test or replace the component: R29 Fuel Filter
    • Go to next step: If the test lamp turns On 
  11. Ignition/Vehicle & All vehicle systems - Off
  12. Install the component: KR22 Fuel Heater Relay
  13. Disconnect the electrical connector: R29 Fuel Filter
  14. Test for less than 10 ohms between the test points: Ground circuit terminal 1 & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: G405
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 1 @ Component harness & Terminal G405
      • 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 
  15. Connect a test lamp between the test points: Control circuit terminal 2 & Ground circuit terminal 1
  16. Ignition - On/Vehicle - In Service Mode
  17. Perform the scan tool control function: Fuel Heater Relay - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 

      Repair the open/high resistance in the circuit: Control Circuit

    • If the test lamp is always On 

      Repair the short to voltage on the circuit: Control Circuit

    • Go to next step: If the test lamp turns On and Off 
  18. Test or replace the component: R29 Fuel Filter
scientia non olet · About LEMON Manuals