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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 339 (Horn System) >> Diagnostic Information and Procedures >> Horns Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 GMC Acadia. 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 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 
  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 1X1@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 1X1 & Ground circuit terminal 1X2
  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

  1. Ignition/Vehicle » Off
  2. Disconnect the electrical connector:X5 X50A Fuse Block - Underhood
  3. Ignition » On / Vehicle » In Service Mode
  4. Momentarily connect a 20 A fused jumper wire between the test points:Control circuit terminal 12 X5 & B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:P12L Horn - Left & P12R Horn - Right

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:P12L Horn - Left & P12R Horn - Right
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 13 X5@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 13 X5 @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 13 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:P12L Horn - Left & P12R Horn - Right
    • If the component turns On and Off 
  5. Connect the electrical connector:X5X50A Fuse Block - Underhood
  6. Disconnect the electrical connector:X5K9 Body Control Module
  7. Ignition » On / Vehicle » In Service Mode
  8. Momentarily connect a 3 A fused jumper wire between the test points:Control circuit terminal 19 X5 & B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:P12L Horn - Left & P12R Horn - Right

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector:X1 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 19 X5 @Control module harness & Ground<!--Name of Circuit-->
      • 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 19 X5 @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 16 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 
  9. Replace the component:K9 Body Control Module

Test 3

    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 appropriate electrical connector:P12L Horn - Leftor P12R Horn - Right
  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 13 X5 @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:P12 Horn
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