Buick Encore: Horns - Diagnostic information and procedures
DTC B2750: Horn relay secondary circuit
DIAGNOSTIC CODE INDEX
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptors
DTC B2750
Horn Relay Secondary Circuit
For symptom byte information refer to: Symptom Byte List
Diagnostic Fault Information
Circuit/System Description
The Body Control Module provides a ground for the Horn printed circuit board
relay within the underhood fuse
block. The underhood fuse block will then provide B+ voltage to the horn control
circuit, sounding the horn.
Conditions for Running the DTC
When the horn output is actively being requested by the Body Control Module.
Conditions for Setting the DTC
B2750 01
The Body Control Module detects a short to voltage in the horn relay control
circuit.
B2750 02
The Body Control Module detects a short to ground in the horn relay control
circuit.
B2750 04
The Body Control Module detects an open/high resistance in the horn relay
control circuit.
Action Taken When the DTC Sets
B2750 01, B2750 04
The Body Control Module will command the horn when requested but the horn
will be inoperative.
B2750 02
The horn will sound continuously until the horn is disconnected or when the
horn overheats and becomes
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 (Encore), Horn Schematics (Encore)
Connector End View Reference
WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS -
INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT
CONNECTOR END VIEWS - INDEX - Encore
Description and Operation
Horns System Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON.
- Verify the operation of the P12 Horn when commanding the Horn Relay On
and Off with a scan tool.
- If the P12 Horn is always ON or always OFF
Refer to Circuit/System Testing.
- If the P12 Horn turns ON and OFF
- All OK.
Circuit/System Testing
- Ignition OFF, disconnect the X1 harness connector at the X50A Fuse
Block-Underhood, ignition ON.
- Verify the P12 Horn is not activated.
- If the P12 Horn is activated
- Ignition OFF, disconnect the harness connector at the P12 Horn, ignition
ON.
- Test for less than 1 V between the control circuit terminal 2 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, test or replace the P12 Horn.
- If the P12 Horn is not activated
- Connect a 15A fused jumper wire between the control circuit terminal D4
and B+.
- Verify the P12 Horn activates.
If the P12 Horn does not activate
- Ignition OFF, remove the jumper wire, disconnect the harness connector
at the P12 Horn, ignition
ON.
- 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
- 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, test or replace the P12 Horn.
- If the P12 Horn activates
- Ignition OFF, connect the X1 harness connector at the X50A Fuse Block-Underhood.
Disconnect the X5
harness connector at the K9 Body Control Module, ignition ON.
- Verify the P12 Horn is not activated.
- If the P12 Horn is activated
- Ignition OFF, disconnect the X2 harness connector at the X50A Fuse
Block-Underhood.
- Test for infinite resistance between the control circuit terminal 19 X5
at the K9 Body Control
Module and ground.
- If less than Infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, test or replace the X50A Fuse Block-Underhood.
- If the P12 Horn is not activated
- Connect a 3 A fused jumper wire between the control circuit terminal 19
and ground.
- Verify the P12 Horn activates.
- If the P12 Horn does not activate
- Ignition OFF, remove the jumper wire, disconnect the X2 harness
connector at the X50A Fuse
Block-Underhood, ignition ON.
- Test for less than 1 V between the control circuit terminal 19 X5 at the
K9 Body Control Module
and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- 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, test or replace the X50A Fuse Block-Underhood.
- If the P12 Horn activates
- Replace the K9 Body Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Front Compartment Fuse Block Replacement
- Control Module References for Body Control Module replacement,
programming and setup
SYMPTOMS - HORNS
IMPORTANT: The following steps must be completed before using the
symptom tables:
- Perform Diagnostic System Check - Vehicle , before using the symptom
tables in order to verify that all of the following are true:
- There are no DTCs set
- The control modules can communicate via the serial data link
- Review the system operation in order to familiarize yourself with the
system functions. Refer to Horns System Description and Operation.
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the
horn system. Refer to Checking
Aftermarket Accessories .
- Inspect the easily accessible or visible system components for obvious
damage or conditions which could
cause the symptom.
- 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
Symptom List
Refer to a symptom diagnostic procedure Horns Malfunction in order to
diagnose the symptom.
Horns malfunction
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The body control module monitors the horn switch signal circuit, when the
horn pad is pressed, the body control
module detects the drop in the horn switch signal circuit and provides a ground
for the horn printed circuit
board relay within the underhood fuse block. The underhood fuse block will then
provide B+ voltage to the
horn control circuit, sounding the horns
Diagnostic Aids
A short to ground in the horn relay control circuit or a short to voltage in
the horn control circuit will cause the
horns to sound continuously until the horns overheat and become inoperative.
Rotate the steering wheel while pressing the horn pad to identify intermittent
and poor connections within the
steering column.
If diagnosing a Horn- Poor Tone condition, inspect the following:
- Debris or water in the horn assembly
- Proper horn mounting hardware torque-Refer to Fastener Tightening
Specifications.
- Debris in the joint where the horns attach to the vehicle
- Debris in direct contact with the horn
- Vehicle components vibrating while the horn is sounding
Reference Information
Schematic Reference
Horn Schematics (Encore), Horn Schematics (Encore)
Connector End View Reference
WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS -
INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT
CONNECTOR END VIEWS - INDEX - Encore
Description and Operation
Horns System Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON.
- Verify the scan tool Horn Command Relay parameter changes between Active
and Inactive when
pressing and releasing the horn pad.
- If the parameter does not change
Refer to Circuit/System Testing - Horn Switch Malfunction
- Verify the P12A Horn-High Note and P12B Horn-Low Note turns ON and OFF
and emit a clear and even
tone when commanding the Horn Relay On and Off with a scan tool.
- If both P12A Horn-High Note and P12B Horn-Low Note do not turn ON and
OFF
Refer to Circuit/System Testing - Horns or Horn Command Malfunction.
- If a single P12 Horn does not turn ON or OFF or if the sound emitted
is not clear and even
Refer to Circuit/System Testing - Horn - Poor Tone.
- If the horns turn ON and OFF and emit a even and clear tone
- All OK.
Circuit/System Testing
Horn Switch Malfunction
NOTE: Refer to SIR Service Precautions
- Ignition OFF, disconnect the X1 harness connector at the X85 Steering
Wheel Air Bag Coil. Ignition ON
- Verify the scan tool Horn Command Relay parameter is Inactive.
- Ignition OFF, disconnect the harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 1 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 Inactive
- Install a 3 A fused jumper wire between the signal circuit terminal 1
and ground.
- Verify the scan tool Horn Command Relay parameter is Active.
- Ignition OFF, remove the jumper wire, disconnect the harness connector
at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 ohms in the signal 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 Active
- Test or replace the S33 Horn Switch.
Horns or Horn Command Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate P12
Horn.
- Connect a test lamp between the control circuit terminal 2 and ground,
ignition ON.
- Verify the test lamp does not turn ON and OFF when commanding the Horn
Relay On and Off with a
scan tool.
- If the test lamp turns ON and OFF
Test or replace the P12 Horn.
- If the test lamp does not turn ON and OFF
- Ignition OFF, connect the harness connector at the P12 Horn. Disconnect
the X1 harness connector at the
X50A Fuse Block-Underhood, ignition ON.
- Verify the P12A Horn-High Note and P12B Horn-Low Note are not activated.
- If the P12A Horn-High Note and P12B Horn-Low Note is activated
- Ignition OFF, disconnect the harness connector at the P12A Horn-High
Note and P12B Horn-Low
Note, ignition ON.
- Test for less than 1 V between the control circuit terminal 2 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, test or replace the P12A Horn-High Note and P12B
Horn-Low Note.
- If the P12A Horn-High Note and P12B Horn-Low Note is not activated
- Connect a 15 A fused jumper wire between the control circuit terminal
listed below and B+.
- Control circuit terminal D4
- Control circuit terminal C6
- Verify the P12A Horn-High Note or P12B Horn-Low Note activates.
- If the P12A Horn-High Note and P12B Horn-Low Note does not activate
- Ignition OFF, remove the jumper wire, disconnect the harness connector
at the P12 Horn, ignition
ON.
- 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
- 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, test or replace the P12 Horn.
- If the P12A Horn-High Note and P12B Horn-Low Note activates
- Ignition OFF, connect the X1 harness connector at the X50A Fuse Block-Underhood.
Disconnect the X5
harness connector at the K9 Body Control Module, ignition ON.
- Verify the P12A Horn-High Note and P12B Horn-Low Note are not activated.
- If the P12A Horn-High Note and P12B Horn-Low Note is activated
- Ignition OFF, disconnect the X2 harness connector at the X50A Fuse
Block-Underhood.
- Test for infinite resistance between the control circuit terminal 19 X5
at the K9 Body Control
Module and ground.
- If less than Infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the X50A Fuse Block-Underhood.
- If the P12A Horn-High Note and P12B Horn-Low Note are not activated
- Connect a 3 A fused jumper wire between the control circuit terminal 19
and ground.
- Verify the P12A Horn-High Note and P12B Horn-Low Note activates.
- If the P12 Horn does not activate
- Ignition OFF, remove the jumper wire, disconnect the X2 harness
connector at the X50A Fuse
Block-Underhood, ignition ON.
- Test for less than 1 V between the control circuit terminal 19 X5 at the
K9 Body Control Module
and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- 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 X50A Fuse Block-Underhood.
- If the P12A Horn-High Note and P12B Horn-Low Note activates
- Replace the K9 Body Control Module.
Horn - Poor Tone
- Ignition OFF and all vehicle systems OFF, disconnect the harness
connector at the appropriate P12 Horn.
It may take up to 2 minutes for all vehicle systems to power down.
- Test for less than 1 ohms between the ground circuit terminal 1 and
ground.
- Ignition OFF.
- Test for less than 2 ohms in the ground circuit end to end.
- If 2 ohms or greater, repair the high resistance in the circuit.
- If less than 2 ohms, repair high resistance in the ground connection.
- If less than 1 ohms
- Ignition OFF, disconnect the X1 harness connector at the X50A Fuse
Block-Underhood.
- Test for less than 2 ohms between the control circuit terminals listed
below:
- P12B Horn-Low Note control circuit terminal 2 and X50A Fuse Block-Underhood
control circuit
terminal D4 X1
- P12A Horn-High Note control circuit terminal 2 and X50A Fuse Block-Underhood
control circuit
terminal C6 X1
- If 2 ohms or greater
Repair the high resistance in the control circuit.
- Test or replace the P12 Horn.
Component Testing
Horn Test
- Ignition OFF, disconnect the harness connector at the appropriate P12
Horn.
- Install a 15 A fused jumper wire between the control terminal 2 and 12
V. Install a jumper wire between
the ground terminal 1 and ground.
- Verify the P12 Horn turns ON and OFF
- If the P12 Horn does not turn ON and OFF
Replace the P12 Horn.
- If the P12 Horn turns ON and OFF
- All OK
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Steering Wheel Horn Contact Replacement (Encore), Steering Wheel Horn
Contact Replacement
(Encore)
- Horn Replacement
- Front Compartment Fuse Block Replacement
- Control Module References for body control module replacement,
programming and setup
READ NEXT:
HORN REPLACEMENT
Fig. 3: Horn
Horn Replacement
STEERING WHEEL HORN CONTACT REPLACEMENT (ENCORE)
Fig. 4: Steering Wheel Horn Contact (Encore)
Steering Wheel Horn Contact Replacement (Encore)
HORNS SYSTEM DESCRIPTION AND OPERATION
System Description
The horn system consists of the following components:
HORN fuse
Underhood fuse block (contains PCB horn relay)
Horn switch
Horn-low note
Schematic wiring diagrams
IMMOBILIZER WIRING SCHEMATICS (ENCORE)
Immobilzer System
Fig. 1: Immobilzer System
IMMOBILIZER WIRING SCHEMATICS (Encore)
Immobilzer System
Fig. 2: Immobilzer System
SEE MORE:
NOTE: Examples used in this article are general in nature and do
not necessarily relate
to a specific engine or system. Illustrations and procedures have been chosen
to guide mechanic through engine overhaul process. Descriptions of processes
of cleaning, inspection, assembly and machine shop pract
The LATCH system secures a child
restraint during driving or in a crash.
LATCH attachments on the child
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restraint to the anchors in the
vehicle. The LATCH system is
designed to make installation of a
child restraint easier.
In order to use the LATCH system in