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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 257 (Horn System) >> Diagnostic Information and Procedures >> Horns Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

Test 1

    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.

  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector:X1&X2@S33 Horn Switch
  3. 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 1X2@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 
  4. Ignition » On / Vehicle » In Service Mode
  5. Verify the scan tool parameter:Horn Switch=Inactive
    • If not the specified state 
    1. Ignition/Vehicle » Off
    2. Disconnect the electrical connector:X3@K9 Body Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 1 X1 @Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance » Replace the component:K9 Body Control Module
    • If the specified state 
  6. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 1 X1&Ground circuit terminal 1 X2
  7. Verify the scan tool parameter:Horn Switch =Active
    • If not the specified state 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:X3@K9 Body Control Module
    3. Ignition On/Vehicle in Service Mode.
    4. Test for less than 1 V between the test points:Signal circuit terminal 1 X1@Component harness&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:Signal circuit terminal 1 X1@Component harness&Terminal 18 X3@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 specified state 
  8. Test or replace the component:S33 Horn Switch

Test 2

    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.

  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector:P13 Horn Assembly
  3. Test for less than 1 Ω between the test points:Ground circuit terminal 1 &Ground
    • If 1 Ω or greater 
    1. Ground Connection»Disconnect
    2. Test for less than 1 Ω between the test points:Ground circuit terminal 1 &Ground Connection
      • If 1Ω or greater » Repair the open/high resistance in the circuit.
    • If less than 1 Ω 
  4. Connect the electrical connector:P13 Horn Assembly
  5. Disconnect the electrical connector:X5@X50A Fuse Block - Underhood
  6. Ignition » On / Vehicle » In Service Mode
  7. Momentarily connect a 15A fused jumper wire between the test points:Control circuit terminal 28 X5&B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:P13 Horn Assembly

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:P13 Horn Assembly
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 2@Component harness&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 infinite resistance between the test points:Control circuit terminal 2 @Component harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance
    7. Test for less than 2 Ω between the test points:Control circuit terminal 2@Component harness&Control circuit terminal 28 X5@Fuse Block Harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Test or replace the component:P13 Horn Assembly
    • If the component turns On and Off 
  8. Connect the electrical connector:X5@X50A Fuse Block - Underhood
  9. Disconnect the electrical connector:X5 @K9 Body Control Module
  10. Ignition » On / Vehicle » In Service Mode
  11. Momentarily connect a 3 A fused jumper wire between the test points:Control circuit terminal 19X5&B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:P13 Horn Assembly

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:X5@X50A Fuse Block - Underhood
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 19X5@Control module harness&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 infinite resistance between the test points:Control circuit terminal 19X5 @Control module harness&Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance
    7. Test for less than 2 Ω between the test points:Control circuit terminal 19 X5 @Control module harness&Terminal 2 X1@Fuse Block Harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Test or replace the component:X50A Fuse Block - Underhood
    • If the component turns On and Off 
  12. Replace the component:K9 Body Control Module

Test 3

    NOTE:

    It may take up to 1 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector:P13 Horn Assembly
  3. Test for less than 1 Ω between the test points:Ground circuit terminal 1 &Ground
    • If 1 Ω or greater 
    1. Ground Connection»Disconnect
    2. Test for less than 1 Ω between the test points:Ground circuit terminal 1 &Ground Connection
      • If 1 Ω or greater » Repair the open/high resistance in the circuit.
    • If less than 1 Ω 
  4. Disconnect the electrical connector:X5@X50A Fuse Block - Underhood
  5. Test for less than 1 Ω between the test points:Control circuit terminal 2@Component harness&Control circuit terminal 28 X @Fuse Block Harness
    • If 1 Ω or greater » Repair the open/high resistance in the circuit.
    • If less than 1 Ω 
  6. Test or replace the component:P13 Horn Assembly
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