Ford Fiesta Manuals

Ford Fiesta: Horn / Horn. Diagnosis and Testing

Ford Fiesta 2014 - 2019 Service Manual / Instrumentation and Warning Systems / Horn / Horn. Diagnosis and Testing

DTC Chart(s)

DTC Chart: Horn

Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices.
REFER to: Diagnostic Methods (100-00 General Information, Description and Operation).


  Body Control Module (BCM) DTC Chart


DTC Description Actions
B1323:23 Horn Switch: Signal Stuck Low   GO to Pinpoint Test B

Symptom Chart(s)

Symptom Chart: Horn

Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices.
REFER to: Diagnostic Methods (100-00 General Information, Description and Operation).


  Symptom Chart


Condition Possible Sources Actions
The horn is inoperative Refer to the pinpoint test   GO to Pinpoint Test A
The horn is always on Refer to the pinpoint test   GO to Pinpoint Test B

Pinpoint Tests

Diagnostic Overview

The Horn Is Inoperative


Refer to Wiring Diagrams Cell 44 for schematic and connector information.

Normal Operation and Fault Conditions


REFER to: Horn - System Operation and Component Description (413-06 Horn, Description and Operation).

Possible Causes

  • Fuse
  • Wiring, terminals or connectors
  • Clockspring
  • Horn
  • Steering wheel wiring harness
  • Driver airbag (includes horn switch)
  • BCM

Visual Inspection and Diagnostic Pre-checks

  • Inspect BJB fuse 38 (20A).

PINPOINT TEST A: THE HORN IS INOPERATIVE
A1 CHECK THE BCM (BODY CONTROL MODULE) HORN OUTPUT USING THE HORN OUTPUT (HORN) PID (PARAMETER IDENTIFICATION)
  • Ignition ON.
  • Using a diagnostic scan tool, view BCM Parameter Identifications (PIDs).
  • Select the active command BCM HORN PID . Command the horn ON and then OFF.

Does the horn sound when commanded on?
Yes GO to A7
No GO to A2

A2 CHECK FOR VOLTAGE AT THE HORN USING THE HORN OUTPUT (HORN) PID (PARAMETER IDENTIFICATION)
  • Ignition OFF.
  • Disconnect: Horn C131.
  • Ignition ON.
  • Using a diagnostic scan tool, view BCM Parameter Identifications (PIDs).
  • Select the active command BCM HORN PID . Command the horn ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C131-2   Ground

Is the voltage greater than 11 volts?
Yes Command the horn OFF. GO to A3
No Command the horn OFF. GO to A4

A3 CHECK THE HORN GROUND CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C131-1   Ground

Is the resistance less than 3 ohms?
Yes INSTALL a new horn.
REFER to: Horn (413-06 Horn, Removal and Installation).
No REPAIR the circuit.

A4 CHECK THE BATTERY VOLTAGE SUPPLY TO THE BCM (BODY CONTROL MODULE)
  • Ignition OFF.
  • Disconnect: BCM C2280A.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280A-3   Ground

Is the voltage greater than 11 volts?
Yes GO to A5
No VERIFY the BJB fuse 38 (20A) is OK. If OK, REPAIR the open circuit. If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.

A5 CHECK THE HORN VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280A-2   C131-2

Is the resistance less than 3 ohms?
Yes GO to A6
No REPAIR the circuit.

A6 CHECK THE HORN VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C131-2   Ground

Is the resistance greater than 10000 ohms?
Yes GO to A14
No REPAIR the circuit.

A7 CHECK FOR HORN SWITCH INPUT
  • Ignition OFF.
  • Disconnect: BCM C2280E.
  • While pressing the horn, measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280E-1   Ground

Is the resistance less than 3 ohms?
Yes GO to A14
No GO to A8

A8 CHECK HORN OPERATION WITH HORN SWITCH CIRCUITS ISOLATED

NOTE: Test is carried out with jumper at female (harness) side of connector.

  • Connect: BCM C2280E.
  • Disconnect: Clockspring C218B.
  • Connect a fused jumper wire:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C218B-11   Ground

Does the horn sound?
Yes REMOVE the fused jumper wire. GO to A10
No REMOVE the fused jumper wire. GO to A9

A9 CHECK THE HORN SWITCH CIRCUIT FOR AN OPEN
  • Disconnect: BCM C2280E.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280E-1   C218B-11

Is the resistance less than 3 ohms?
Yes REPAIR the open horn switch ground circuit GD116 (BK/VT).
No REPAIR the open horn switch circuit.

A10 CHECK THE HORN SWITCH GROUND CIRCUIT FOR AN OPEN
  • Disconnect: BCM C2280E.
  • Connect: Clockspring C218B.
  • Remove the driver airbag.
    REFER to: Driver Airbag (501-20B Supplemental Restraint System, Removal and Installation).
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C217A-1   C2280E-1

Is the resistance less than 3 ohms?
Yes GO to A11
No GO to A12

A11 CHECK THE HORN SWITCH GROUND CIRCUIT
  • Ignition OFF.
  • Disconnect Horn Switch C217B.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C217B-1   Ground

Is the resistance less than 3 ohms?
Yes INSTALL a new driver airbag (includes horn switch).
REFER to: Driver Airbag (501-20B Supplemental Restraint System, Removal and Installation).
No GO to A13

A12 CHECK THE HORN SWITCH CIRCUIT AT THE STEERING WHEEL HARNESS
  • Disconnect: Clockspring C218C.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C217A-1   C218C-4

Is the resistance less than 3 ohms?
Yes INSTALL a new clockspring.
REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation).
No INSTALL a new steering wheel (includes steering wheel wiring harness).
REFER to: Steering Wheel (211-04 Steering Column, Removal and Installation).

A13 CHECK THE HORN SWITCH GROUND CIRCUIT AT THE STEERING WHEEL HARNESS
  • Disconnect: Clockspring C218C.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C217B-1   C218C-8

Is the resistance less than 3 ohms?
Yes INSTALL a new clockspring.
REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation).
No INSTALL a new steering wheel (includes steering wheel wiring harness).
REFER to: Steering Wheel (211-04 Steering Column, Removal and Installation).

A14 CONFIRM THE BCM (BODY CONTROL MODULE) FAULT
  • Ignition OFF.
  • Inspect the BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals – clean module pins)
    • damaged or bent pins – install new terminals/pins
    • pushed-out pins – install new pins as necessary
  • Connect: Horn C131 (if previously disconnected).
  • Connect: BCM C2280A (if previously disconnected).
  • Connect: BCM C2280E (if previously disconnected).
  • Make sure all connectors seat and latch correctly.
  • Operate the system and determine if the concern is still present.

Is the concern still present?
Yes CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new BCM .
REFER to: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.


Diagnostic Overview

The Horn Is Always On


Refer to Wiring Diagrams Cell 44 for schematic and connector information.

Normal Operation and Fault Conditions


REFER to: Horn - System Operation and Component Description (413-06 Horn, Description and Operation).


  DTC Chart


DTC Description Fault Trigger Condition
B1323:23 Horn Switch: Signal Stuck Low A fault is indicated when the BCM detects the horn switch pressed or a short to ground exists on the horn switch signal circuit for greater than 120 seconds. This DTC also sets if the horn switch is pressed during the BCM self test.

Possible Causes

  • Wiring, terminals or connectors
  • Clockspring
  • Steering wheel wiring harness
  • Driver airbag (includes horn switch)
  • BCM

PINPOINT TEST B: THE HORN IS ALWAYS ON
B1 ISOLATE THE HORN SWITCH AND CIRCUITS
  • Ignition OFF.
  • Disconnect: BCM C2280E.

Does the horn continue to sound?
Yes GO to B2
No GO to B3

B2 ISOLATE THE BCM (BODY CONTROL MODULE)
  • Disconnect: BCM C2280A.

Does the horn continue to sound?
Yes REPAIR circuit CRH04 (VT/GN) for a short to voltage.
No GO to B6

B3 ISOLATE THE HORN SWITCH
  • Remove the driver airbag.
    REFER to: Driver Airbag (501-20B Supplemental Restraint System, Removal and Installation).
  • Connect: BCM C2280E.

Does the horn continue to sound?
Yes DISCONNECT BCM C2280E. GO to B4
No DISCONNECT BCM C2280E. INSTALL a new driver airbag (includes horn switch).
REFER to: Driver Airbag (501-20B Supplemental Restraint System, Removal and Installation).

B4 CHECK THE HORN SWITCH SIGNAL CIRCUIT FOR A SHORT TO GROUND
  • Disconnect: Clockspring C218B.
  • Connect: BCM C2280E.

Does the horn continue to sound?
Yes REPAIR the circuit.
No DISCONNECT BCM C2280E. GO to B5

B5 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND
  • Connect: Clockspring C218B.
  • Disconnect: Clockspring C218C.
  • Connect: BCM C2280E.

Does the horn continue to sound?
Yes INSTALL a new clockspring.
REFER to: Clockspring (501-20B Supplemental Restraint System, Removal and Installation).
No INSTALL a new steering wheel (includes steering wheel wiring harness).
REFER to: Steering Wheel (211-04 Steering Column, Removal and Installation).

B6 CONFIRM THE BCM (BODY CONTROL MODULE) FAULT
  • Ignition OFF.
  • Inspect the BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals – clean module pins)
    • damaged or bent pins – install new terminals/pins
    • pushed-out pins – install new pins as necessary
  • Connect: BCM C2280A.
  • Connect: BCM C2280E.
  • Make sure all connectors seat and latch correctly.
  • Operate the system and determine if the concern is still present.

Is the concern still present?
Yes CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new BCM .
REFER to: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.


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