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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 22 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (2 Of 3)) >> Diagnostic Information and Procedures >> DTC P0685-P0687, P0689, P0690, P1682, P16A7, P16AF, or P16B3 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
    NOTE:
    • For detailed component terminal information, refer to : Diagnostic Aids
    • Circuit 5290 / 5291 / 5292 referenced in this procedure are not applicable to all applications.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Remove the component : KR75 Engine Controls Ignition Relay
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points :
    • B+ - Relay Coil & Ground
    • B+ - Relay Switch & Ground
    • If the test lamp does not turn On 

      Replace the component : X50A Fuse Block - Underhood

    • Go to next step : If the test lamp turns On 
  5. Connect a test lamp between the test points : B+ - Relay Coil & Control - Relay Coil
  6. Perform the scan tool control function : Engine Controls Ignition Relay - 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 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 : Control - Relay Coil @ Relay Socket & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step : If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points : Control - Relay Coil @ Relay Socket & 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 appropriate electrical connector : K20 Engine Control Module
    3. Test for infinite resistance between the test points : Control - Relay Coil @ 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 turns On and Off 
  7. Verify the fuse that supplies voltage to the following circuit(s) is not open : 5290 / 5291 / 5292 - For the circuit that set the DTC.
    • If the fuse is open 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the appropriate electrical connector : K20 Engine Control Module
    3. Test for infinite resistance between the test points : Output terminal @ Fuse & 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 fuse is not open 
  8. Verify a test lamp does not turn On between the test points : Control - Component @ Relay Socket & Ground
    • Go to next step : If the test lamp turns On 
    1. Ignition/Vehicle & All vehicle systems - 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 circuits : 5290 / 5291 / 5292 @ Control module 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 does not turn On 
  9. Ignition/Vehicle - Off
  10. Connect a 30 A fused jumper wire between the test points : Control - Component & B+ - Relay Switch @ Relay Socket
  11. Ignition - On / Vehicle - In Service Mode
  12. Verify the scan tool parameter :
    • Engine Controls Ignition Relay Feedback Signal = Within 1 V of the battery voltage
    • Engine Controls Ignition Relay Feedback 2 Signal = Within 1 V of the battery voltage
    • If not within 1 V of the battery voltage 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the appropriate electrical connector : K20 Engine Control Module
    3. Test circuit 5290 / 5291 / 5292 for less than 2 between the test points : Control - Component @ Relay Socket & 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 within 1 V of the battery voltage 
  13. Test or replace the component : KR75 Engine Controls Ignition Relay
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