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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Controls And Fuel - 6.0L (L96) - DTC P0351 To DTC P2636 And Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P0685, P0686, P0687, P0689, P0690 Or P1682: Engine Controls Ignition Relay/Ignition 1 Switch Circuit 2 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle - Off
  2. Remove the component: KR75 Engine Controls Ignition Relay
  3. Verify a test lamp turns On between the test points:
    • B+ circuit terminal 30 & Ground
    • B+ circuit terminal 86 & 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 
  4. Ignition - On/Vehicle - In Service Mode
  5. Connect a test lamp between the test points: Control circuit terminal 85 & B+ circuit terminal 86
  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 circuit terminal 85 @ Relay Socket & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 Ω between the test points: Control circuit terminal 85 @ Relay Socket & The other end of the circuit @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - 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 circuit terminal 85 @ 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 is not open: F47UA Fuse
    • 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. Ignition - On/Vehicle - In Service Mode
  9. Verify a test lamp does not turn On between the test points: Ignition circuit terminal 87 @ Relay Socket & Ground
    • Go to next step: If the test lamp turns On 
  10. Disconnect the appropriate electrical connector: K20 Engine Control Module
  11. Test for less than 1 V between the test points: Ignition circuit terminal 28 @ Control module harness & Ground
    • If 1 V or greater - Repair the short to voltage on the circuit.
    • If less than 1 V - Test or replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp does not turn On 
  12. Ignition/Vehicle - Off
  13. Connect a 30 A fused jumper wire between the test points: Ignition circuit terminal 87 & B+ circuit terminal 30
  14. Ignition - On/Vehicle - In Service Mode
  15. Verify the scan tool parameter: Engine Controls Ignition Relay Feedback 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 for less than 2 ohms between the test points: Ignition circuit terminal 87 @ Relay Socket & Ignition circuit terminal 28 @ 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 
  16. Test or replace the component: KR75 Engine Controls Ignition Relay
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