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Home >> Chevrolet >> 2018 >> Spark LT, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Fixed And MOVEABLE Window System) >> Diagnostic Information and Procedures >> Rear Window Defogger Malfunction (Without C68) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Chevrolet Spark. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
    NOTE: 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.
  2. Remove the component: KR5 Rear Defogger Relay
  3. Test for less than 10 Ω between the test points: Ground circuit terminal 86 & Ground
    • If 10 Ω or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 Ω between the test points: Ground circuit terminal 86 & Ground Connection
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  4. Connect a test lamp between the test points: Control circuit terminal 85 & Ground circuit terminal 86
  5. Ignition - On / Vehicle - In Service Mode
  6. Operate the component: Rear Defogger Switch - Pressed

    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 electrical connector: K9 Body 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
    4. Test for less than 2 Ω between the test points: Control circuit terminal 85 @ Relay Socket & Terminal 11 X5 @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Replace the component: K9 Body Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K9 Body 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 - Replace the component: K9 Body Control Module
    • If the test lamp turns On and Off 
  7. Momentarily connect a 25 A fused jumper wire between the test points: B+ circuit terminal 30 & Control circuit terminal 87

    Verify the component does not turn On and Off when connecting and disconnecting the jumper wire: E18 Rear Defogger Grid

    • If the component turns On and Off 

      Test or replace the component: KR5 Rear Defogger Relay

    • If the component does not turn On and Off 
  8. Ignition/Vehicle & All vehicle systems - Off
  9. Install the component: KR5 Rear Defogger Relay
  10. Disconnect the electrical connector: X1 & X2 @ E18 Rear Defogger Grid
  11. Test for less than 10 Ω between the test points: Ground circuit terminal 1 X2 & Ground
    • If 10 Ω or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 Ω between the test points: Ground circuit terminal 1 X2 @ Component harness & Ground Connection
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  12. Connect a test lamp between the test points: Control circuit terminal 1 X1 & Ground circuit terminal 1 X2
  13. Ignition - On / Vehicle - In Service Mode
  14. Perform the scan tool control function: Rear Defogger - 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

    • If the test lamp turns On and Off 
  15. Test or replace the component: E18 Rear Defogger Grid
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