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Home >> Chevrolet >> 2021 >> Trailblazer L >> Repair and Diagnosis >> Accessories & Equipment >> Drivers Assistance Systems - ADAS >> Driver Assistance Systems >> Diagnostic Information and Procedures >> Forward Collision Alert System Malfunction >> Circuit/System Testing

Circuit/System Testing

Test 1

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
  3. Ignition/Vehicle - On
  4. Test for 11.8 to 12.2 V between the test points: 12 V Reference circuit terminal 10 & Ground
    • If greater than 12.2 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X3 @ K9 Body Control Module
    3. Ignition/Vehicle - On
    4. Test for less than 1 V between the test points: 12 V Reference circuit terminal 10 @ Component harness & Ground
      • If 1 V or greater

        Repair the short to voltage on the circuit.

      • Go to next step: If less than 1 V
    5. Replace the component: K9 Body Control Module
    • If less than 11.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X3 @ K9 Body Control Module
    3. Test for infinite resistance between the test points: 12 V Reference circuit terminal 10 @ 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: 12 V Reference circuit terminal 10 @ Component harness & 12 V Reference circuit terminal 4 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K9 Body Control Module
    • Go to next step: If greater than 3 V 
  5. Ignition/Vehicle & All vehicle systems - Off
  6. Connect the electrical connector: S70L Steering Wheel Controls Switch - Left
  7. Disconnect the electrical connector: X3 @ K9 Body Control Module
  8. Ignition/Vehicle - On
  9. Test for less than 1 V between the test points: Signal circuit terminal 16 & Ground
    • If 1 or greater 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
    3. Ignition/Vehicle - On
    4. Test for less than 1 V between the test points: Signal circuit terminal 16 @ Control module harness & Ground
      • If 1 V or greater 

        Repair the short to voltage on the circuit.

      • Go to next step: If less than 1 V 
    5. Replace the component: S70L Steering Wheel Controls Switch - Left
    • Go to next step: If less than 1 V 
  10. Ignition/Vehicle & All vehicle systems - Off
  11. Test for infinite resistance between the test points: Signal circuit terminal 16 & Ground
    • If less than infinite resistance 
    1. Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
    2. Test for infinite resistance between the test points: Signal circuit terminal 16 @ Control module harness & Ground
      • If less than infinite resistance

        Repair the short to ground on the circuit.

      • Go to next step: If infinite resistance
    3. Replace the component: S70L Steering Wheel Controls Switch - Left
    • Go to next step: If infinite resistance 
  12. Test for less than infinite resistance between the test points: 12 V Reference circuit terminal 4 & Signal circuit terminal 16
    • If infinite resistance 
    1. Disconnect the electrical connector: S70L Steering Wheel Controls Switch - Left
    2. Test for less than 2 ohms between the test points: Signal circuit terminal 16 @ Control module harness & Signal circuit terminal 4 @ Component harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms
    3. Replace the component: S70L Steering Wheel Controls Switch - Left
    • Go to next step: If less than infinite resistance 
  13. Connect a DMM between the test points: 12 V Reference circuit terminal 4 & Signal circuit terminal 16
  14. Verify the resistance changes when pressing and released the Forward Collision Alert switch.
    • If the resistance does not change 

      Replace the component: S70L Steering Wheel Controls Switch - Left

    • Go to next step: If the resistance changes 
  15. Replace the component: K9 Body Control Module

Test 2

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: P43 Collision Alert Indicators
  3. Verify a test lamp turns On between the test points: Ground circuit terminal 4 & B+
    • If the test lamp does not turn On 
    1. Test for less than 2 ohms between the test points: Ground circuit terminal 4 & Ground terminal
      • 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 the test lamp turns On 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: Ignition circuit terminal 1 & 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 1 @ P43 Collision Alert Indicators & The other end of the circuit
      • 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 1 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Test or replace the component: P43 Collision Alert Indicators
    • Go to next step: If the test lamp turns On 
  6. Ignition/Vehicle - Off
  7. Disconnect the electrical connector: X1 @ P16 Instrument Cluster
  8. Ignition - On / Vehicle - In Service Mode
  9. Test for less than 1 V between the test points:
    • {UDC} Control circuit terminal 30 @ P16 Instrument Cluster & Ground
    • {UDD} Control circuit terminal 11 @ P16 Instrument Cluster & Ground
    • Control circuit terminal 12 @ P16 Instrument Cluster & Ground
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  10. Ignition/Vehicle - Off
  11. Test for infinite resistance between the test points:
    • {UDC} Control circuit terminal 30 @ P16 Instrument Cluster & Ground
    • {UDD} Control circuit terminal 11 @ P16 Instrument Cluster & Ground
    • Control circuit terminal 12 @ P16 Instrument Cluster & Ground
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  12. Test for less than 2 ohms between the test points:
    • {UDC} Control circuit terminal 30 @ P16 Instrument Cluster & Control circuit terminal 3 @ P43 Collision Alert Indicators
    • {UDD} Control circuit terminal 11 @ P16 Instrument Cluster & Control circuit terminal 3 @ P43 Collision Alert Indicators
    • Control circuit terminal 12 @ P16 Instrument Cluster & Control circuit terminal 2 @ P43 Collision Alert Indicators
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 ohms 
  13. Replace the component: P43 Collision Alert Indicators
  14. Ignition - On / Vehicle - In Service Mode
  15. Perform the appropriate scan tool control function: All Indicators

    Verify the component activates: Collision Alert - Indicators

    • If the component does not work as specified 

      Replace the component: P16 Instrument Cluster

    • Go to next step: If the component works as specified 
  16. All OK.
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