B274E

DTC B274E or B274F

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B274E 01
- Low Horn Output Short to Battery

Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) controls the horn relay by providing a ground to 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

The DTC can only set only when the output is actively being requested by the BCM.

Conditions for Setting the DTC

The BCM detects a short to voltage in the horn relay circuit.

Action Taken When the DTC Sets

The horns will be inoperative.

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 Electrical Diagrams

Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1

Description and Operation

Horns System Description and Operation Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify the horns turn On and Off when commanding the Horn Relay On and Off with a scan tool.

• If the horns do not turn On and Off
Refer to Circuit/System Testing.

• If the horns turn On and Off

3. All OK.

Circuit/System Testing

1. Vehicle OFF, disconnect the KR3 horn relay, Vehicle in Service Mode.

2. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle OFF.

2. Test for less than 2 ohms in the B+ circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF.

2. Test for infinite resistance between the B+ circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance,

3. Disconnect the harness connector at the P12L horn-left and the P12R horn-right.

4. Test for infinite resistance between the control circuit terminal 4 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, test or replace the KR3 horn relay.

• If the test lamp illuminates

3. Connect a test lamp between the B+ circuit terminal 2 and the control circuit terminal 5.

4. Vehicle in Service Mode, verify the test lamp turns ON and OFF when commanding the Horn Relay On and Off with a scan tool.

• If the test lamp is always OFF

1. Vehicle OFF, disconnect the harness connector at the K9 body control module, Vehicle in Service Mode.

2. Test for less than 1 V between the control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V

3. Vehicle OFF.

4. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K9 body control module.

• If the test lamp is always ON

1. Vehicle OFF, disconnect the harness connector at the K9 body control module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the K9 body control module.

• If the test lamp turns ON and OFF

5. Test or replace the KR3 horn relay.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)

* Control Module References Programming and Relearning for BCM replacement, programming and setup