Horn System Cadillac CTS I

Fastener Tightening Specifications

Fastener Tightening Specifications

Horns Schematic Icons

Horns Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling Zones. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs

Scheme 1

Scheme 2

Horns Connector End Views

Horn Assembly Connector Part Information 12052644 2-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A BK 250 Ground B D-GN 29 Horn Control

Diagnostic Starting Point - Horns

Begin the system diagnosis with Diagnostic System Check - Horns . The Diagnostic System Check will provide the following information

1. The identification of the control module(s) which command the system.
2. The ability of the control module(s) to communicate through the serial data circuit.
3. The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
2. 4: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - Horns

Symptoms - Horns

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the horn system. Refer to «Checking Aftermarket Accessories»(/cadillac/cts/i-2002-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__checking-aftermarket-accessories) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Perform the following if a horn buzzes or has a harsh tone: Inspect for debris in the joint where the horn fastens to the vehicle. Test the torque of the horn mounting hardware. The horn mounting hardware should be tightened to a torque of 10 N.m (7 lb ft).

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Horns Always On»(/cadillac/cts/i-2002-2007/remont/horns/#horn-system)
2. «Horns Inoperative»(/cadillac/cts/i-2002-2007/remont/horns/#horn-system)
3. «Horns Inoperative - One Horn»(/cadillac/cts/i-2002-2007/remont/horns/#horn-system)
4. «Horns - Poor Tone»(/cadillac/cts/i-2002-2007/remont/horns/#horn-system__horns-poor-tone)

The numbers below refer to the step numbers on the diagnostic table.

1. 4: Tests if ground is constantly being applied to the horn relay.
2. 5: The horn relay control circuit includes the horn slip ring and the horn switch. The horn slip ring and horn switch must be tested for a short to ground when testing the relay control circuit. Refer to «Circuit Testing»(/cadillac/cts/i-2002-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__circuit-testing) and «Wiring Repairs»(/cadillac/cts/i-2002-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__wiring-repairs) in Wiring Systems.

Horns Always On

The numbers below refer to the step numbers on the diagnostic table.

1. 4: Verifies that the dash integration module (DIM) is providing ground to the horn relay.
2. 5: Tests for voltage at the battery positive voltage terminal of the horn relay coil.
3. 7: Tests for voltage at the battery positive voltage terminal of the horn relay switch. The SEATS circuit breaker supplies power to the battery positive voltage terminal of the horn relay switch.
4. 13: The horns need maximum current flow to operate properly. A high resistance, greater than 0.5 ohms, in the horn control circuit or the horn ground circuit could cause operating problems with the horns. Inspect the circuits for faults that would restrict current flow.
5. 15: The horn relay control circuit includes the horn slip ring and the horn switch. The horn slip ring and horn switch must be tested for a high resistance, an open or a short to voltage when testing the relay control circuit. Refer to «Circuit Testing»(/cadillac/cts/i-2002-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__circuit-testing) and «Wiring Repairs»(/cadillac/cts/i-2002-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__wiring-repairs) in Wiring Systems.

Horns Inoperative

The number below refers to the step number on the diagnostic table.

1. 9: The horns need maximum current flow to operate properly. A high resistance, greater than 0.5 ohms, in the horn control circuit or the horn ground circuit could cause operating problems with the horns. Inspect the circuits for faults that would restrict current flow.

Horns Inoperative - One Horn

Horns - Poor Tone

Horns - Poor Tone

Removal Procedure

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/cts/i-2002-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the lower air deflector. Refer to «Air Deflector Replacement - Front Bumper Fascia»(/cadillac/cts/i-2002-2007/remont/exterior-body-panels/#bumpers-fascias) in Bumpers.
3. Loosen the bolt (1) that secures the horn assembly (2) to the body four full turns.
4. Grasp the horn assembly (2) on both sides and rock it back and forth in order to pull it forward on the stud.
5. Slide the horn assembly (2) rearward in order to locate the stud in the large portion of the keyhole slot (4).
6. Disconnect the horn electrical connector (3) from the horn assembly (2).
7. Pull the horn assembly (2) outward in order to remove it from the vehicle.

Installation Procedure

1. Connect the horn electrical connector (3) to the horn assembly (2).
2. Install the stud of the horn assembly (2) into the large portion of the keyhole slot (4).
3. Slide the horn assembly (2) forward in the keyhole slot (4).
4. Tighten the bolt (1) in order to secure the horn assembly (2) to the body side rail. Tighten: Tighten the bolt to 9 N.m (80 lb in).
5. Install the lower air deflector. Refer to «Air Deflector Replacement - Front Bumper Fascia»(/cadillac/cts/i-2002-2007/remont/exterior-body-panels/#bumpers-fascias) in Bumpers.
6. Lower the vehicle.

System Description

The horn system consists of the following components

1. HORN fuse
2. RADIO fuse
3. Horn relay
4. Inflatable restraint steering wheel coil
5. Horn switch
6. Horns
7. Body control module (BCM)
8. Steering wheel radio control switch

System Operation

The vehicle horn system is activated under the following conditions

1. The horn switch is depressed.
2. The body control module (BCM) commands the horns on. The BCM commands the horns on under any of the following conditions: When the content theft deterrent system detects a vehicle intrusion. For further information refer to «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/cts/i-2002-2007/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) in Theft Deterrent. When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information refer to «Keyless Entry System Description and Operation»(/cadillac/cts/i-2002-2007/remont/door-locks-anti-theft-systems/#keyless-entry-system) in Keyless Entry. When the OnStar® system is used to sound the horns if equipped. For further information, refer to «OnStar Description and Operation»(/cadillac/cts/i-2002-2007/remont/entertainment-systems/#cellular-communication-system__onstar-description-and-operation) in Cellular Communications.

Circuit Operation

Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground to the horn relay control circuit. The BCM may also apply ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horns through the horn control circuit. The horns sound as long as ground is applied to the horn relay control circuit.

See also:
• Scan Tool Does Not Power Up
• Diagnostic Trouble Code (DTC) List
• Diagnostic Trouble Code (DTC) List
• Checking Aftermarket Accessories
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Connector Repairs
• Dash Integration Module Replacement
• Lifting and Jacking the Vehicle
• Air Deflector Replacement - Front Bumper Fascia
• Content Theft Deterrent (CTD) Description and Operation
• Keyless Entry System Description and Operation
• OnStar Description and Operation
• Diagnostic System Check - Horns
• Symptoms - Horns
• Horns - Poor Tone
• Fastener Tightening Specifications