2010 Cadillac CTS Sedan AWD V6-3.6L Page 523
Circuit/System Description
The body control module (BCM) controls the HORN relay by grounding the control circuit of the horn relay coil energizing the relay. When the
HORN relay is energized, the horn relay contacts close applying voltage through the HORN fuse and the horn control circuit to the horns.
Conditions for Running the DTC
When the output is actively being requested by the BCM.
Conditions for Setting the DTC
The BCM detects a short to ground, open, or short to voltage in the horn relay control circuit for approximately 125 milliseconds.
Action Taken When the DTC Sets
The BCM disables the output to the horn relay until the next ignition cycle.
Conditions for Clearing the DTC
* The DTC clears when the fault is no longer detected.
* The current DTC will become history when the request for the output is removed.
* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.
Reference Information
Schematic Reference
Horn Schematics (See: Lighting and Horns/Horn/Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Horns System Description and Operation (See: Lighting and Horns/Horn/Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Command the horns ON and OFF with the scan tool. The horns should turn ON and OFF when changing between the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the HORN relay.
2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 86 and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the control circuit
terminal 87 for a short to ground. If all circuits test normal, test or replace the HORN relay.
3. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
