Ford Fiesta Quiz
Electronic Function Group

Perimeter Anti-Theft Alarm Diagnosis and Testing

In this manual: Electronic Function Group
Service Information — 27Suspension — 48Transmission — 9Brake System — 52Steering — 21Engine — 140Manual Transmission, Clutch, Transfer Case and Power Transfer Unit — 48Exhaust System — 6Fuel System — 21Climate Control System — 58Instrumentation and Warning Systems — 26Battery and Charging System — 20Infotainment Systems — 41Lighting — 29Power Distribution — 11Electronic Function Group — 30Body and Paint — 275Frame and Mounting — 3
~16min read
1special tools

DTC Chart

The diagnosis described in this manual assumes a certain level of skill and knowledge of Ford diagnostic methods.
REFER TO: About This Manual (100-00 General Information, Description and Operation).

Trouble Code Description Action
B10B1:92 Interior Set/Reset Switch: Operates or Malfunctions GO to Pinpoint Test B
B112K:87 Interior Motion Sensor: No Message GO to Pinpoint Test F
B112K:96 Interior Motion Sensor: Internal Component Failure INSTALL a new intrusion sensor.
P254F:00 Hood Ajar Switch Circuit / Open: No Subtype Information GO to Pinpoint Test E
All Other Diagnostic Trouble Codes (DTCs) -
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Diagnosis and Testing).

Symptom Chart

Symptom Chart: Anti-Theft - Perimeter

The diagnosis described in this manual assumes a certain level of skill and knowledge of Ford diagnostic methods.
REFER TO: About This Manual (100-00 General Information, Description and Operation).


Symptom Chart


Condition Possible Causes Action
Alarm Does Not Activate From Unauthorized Entry Through the Hood
  • Refer to Pinpoint Test
  • GO to Pinpoint Test A
Alarm Does Not Activate From Unauthorized Door Entry
  • Door ajar input
  • CHECK that the interior lamps do not illuminate with the door open.
    REFER TO: Interior Lighting (417-02 Interior Lighting, Diagnosis and Testing).
Alarm does not activate with unauthorized entry through the liftgate/trunk
  • Liftgate/Trunk Entry
  • CHECK for incorrect liftgate/trunk ajar indication.
    REFER TO: Instrument Cluster, Message Center and Warning Chimes (413-01 Instrument Cluster, Message Center and Warning Chimes, Diagnosis and Testing).
Perimeter alarm does not arm/disarm from the driver door lock cylinder
  • Refer to Pinpoint Test
  • GO to Pinpoint Test B
Alarm does not arm / no turn signal flash confirmation
  • Refer to Pinpoint Test
  • GO to Pinpoint Test C
No sound during alarm activation (horn sound)
  • Horn output problem

  • REFER TO: Horn (413-06 Horn, Diagnosis and Testing).
No sound during alarm activation (anti-theft alarm horn sound)
  • Refer to Pinpoint Test
  • GO to Pinpoint Test D
False alarm
  • Door ajar input
  • Hood ajar input
  • Liftgate/Trunk Ajar Entry
  • Panic alarm button on the RKE transmitter pressed
  • Valid readable PATS key NOT received when the ignition transitions to RUN.
  • An intermittent fault is present. MONITOR the BCM Parameter Identification (PID) for the last alarm event to determine and isolate the cause of the last alarm activation.
    • Most recent event that caused an alarm (ALARM_1)
    • 2nd most recent event that caused an alarm (ALARM_2)
    • 3rd most recent event that caused an alarm (ALARM_3)
    • 4th most recent event that caused an alarm (ALARM_4)

Pinpoint Tests

Alarm does not activate when unauthorized entry through the hood is attempted


For circuit and connector information, refer to Wiring Diagrams Cell 117.

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).

Possible Causes

  • Wiring, Terminals or Connectors
  • Hood Latch
  • BCM

Visual Inspection and Preliminary Diagnosis

  • Inspect the hood latch for damage.

DIAGNOSTIC TEST A: ALARM DOES NOT ACTIVATE FROM UNAUTHORIZED ENTRY THROUGH THE LIFTGATE
A1 CHECK THE BCM (BODY CONTROL MODULE) HOOD AJAR SWITCH (HOOD_SW) PID (PARAMETER IDENTIFICATION)
  • The ignition is on.
  • Using the diagnostic scan tool, view the BCM parameter identification (PID) data.
  • Using a diagnostic scanner, monitor the BCM PID HOOD_SW.
  • Hood Ajar Switch C127.

Does the HOOD_SW PID show AJAR when the switch is disconnected?
Yes INSTALL a new hood latch.
REFER TO: Hood Latch (501-14 Handles, Locks, Latches and Entry Systems, Removal and Installation).
No GO to A2
A2 CHECK THE HOOD AJAR SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect C2280D.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C127-2 Ground

Is the resistance greater than 10000 Ohms?
Yes GO to A3
No REPAIR the circuit.
A3 CHECK THE BCM (BODY CONTROL MODULE) OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect all BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

Perimeter alarm does not arm/disarm with driver door lock cylinder


For circuit and connector information, refer to Wiring Diagrams Cell 117.

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).


DTC Fault Trigger Conditions


Trouble Code Description Fault Trigger Conditions
B10B1:92 Interior Set/Reset Switch: Operates or Malfunctions Sets when the BCM detects a short to ground on one of the input circuits of the driver door lock cylinder during the self-test.

Possible Causes

  • Arm/disarm switch (part of driver door lock)
  • Driver door key cylinder link
  • Driver door lock
  • BCM

DIAGNOSTIC TEST B: PERIMETER ALARM DOES NOT ARM/DISARM FROM DRIVER DOOR LOCK CYLINDER
B1 RETRIEVE STORED DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE BCM (BODY CONTROL MODULE)
  • The ignition is on.
  • Using a scan tool, perform the BCM self-test.

Is DTC B10B1:92 present?
Yes GO to B2
No GO to B4
B2 CHECK THE DRIVER DOOR LATCH FOR INTERNAL SHORT TO GROUND
  • Ignition OFF.
  • Disconnect the driver door latch C525.
  • The ignition is on.
  • Using a scan tool, clear the BCM diagnostic trouble codes (DTCs).
  • Wait 10 seconds.
  • Using a scan tool, perform the BCM self-test.

Is DTC B10B1:92 still present?
Yes GO to B3
No INSTALL a new driver door latch.
REFER TO: Front Door Latch (501-14 Door Handles, Locks, Latches and Entry Systems, Removal and Installation).
B3 CHECK THE DOOR LOCK CYLINDER ARM/DISARM CIRCUITS FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect C2280G.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C2280G-9 Ground
    C2280G-10 Ground

Is the resistance greater than 10000 ohms?
Yes GO to B7
No REPAIR the faulty circuit.
B4 CHECK THE DOME LAMP OPERATION
  • Open and close the driver door while observing the interior lamps.

Do the courtesy lamps operate correctly?
Yes GO to B5
No CHECK the interior lamps.
REFER TO: Interior Lighting (417-02 Interior Lighting, Diagnosis and Testing).
B5 BYPASS THE DRIVER DOOR LATCH WHEN TESTING THE DRIVER DOOR LOCK CYLINDER (KCS_DRVR) PID (PARAMETER IDENTIFICATION)
  • Ignition OFF.
  • Disconnect the driver door latch C525.
  • The ignition is on.
  • Using the diagnostic scan tool, view the BCM parameter identification (PID) data.
  • Using a diagnostic scanner, monitor the BCM PID KCS_DRVR.
  • Momentarily connect:
    Click to display connectors

    Lock


    Positive lead Measurement/Action Negative lead
    C525-1 C525-5

    Click to display the connectors

    Unlock


    Positive lead Measurement/Action Negative lead
    C525-2 C525-5

Does the PID display LOCK and UNLOCK when the jumper wire is connected?
Yes INSTALL a new driver door latch.
REFER TO: Front Door Latch (501-14 Door Handles, Locks, Latches and Entry Systems, Removal and Installation).
No GO to B6
B6 CHECK THE DOOR LOCK CYLINDER ARM/DISARM CIRCUITS FOR AN OPEN
  • Ignition OFF.
  • Disconnect C2280G.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C2280G-9 C525-2
    C2280G-10 C525-1

Is the resistance less than 3 ohms?
Yes GO to B7
No REPAIR the faulty circuit.
B7 CHECK BCM (BODY CONTROL MODULE) OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect the BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

Alarm system does not arm/no turn signal flash confirmation

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).

Possible Causes

  • Door ajar input
  • Hood switch input
  • Liftgate/Trunk Ajar Entry
  • Turn Signal Output
  • RKE transmitter concern
  • BCM

DIAGNOSTIC TEST C: ALARM DOES NOT ARM / NO TURN SIGNAL FLASH CONFIRMATION
C1 RETRIEVE STORED DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE BCM (BODY CONTROL MODULE)
  • The ignition is on.
  • Using a scan tool, perform the BCM self-test.

Is DTC P254F:00 present?
Yes GO to Pinpoint Test E
No GO to C2
C2 CHECK THE AJAR SWITCH INPUT
  • Close all doors.
  • Observe the PMI.

Does the IPC indicate that a door is ajar?
Yes CHECK that the dome lamps are on steadily.
REFER TO: Interior Lighting (417-02 Interior Lighting, Diagnosis and Testing).
No GO to C3
C3 MONITOR THE LIFTGATE/LUGGAGE COMPARTMENT LID AJAR SWITCH INPUT
  • Close the liftgate/trunk lid.
  • Observe the PMI.

Does the IPC indicate that the liftgate/luggage compartment lid is ajar?
Yes CHECK for incorrect liftgate/trunk ajar indication.
REFER TO: Instrument Cluster, Message Center and Warning Chimes (413-01 Instrument Cluster, Message Center and Warning Chimes, Diagnosis and Testing).
No GO TO C4
C4 CHECK THE OPERATION OF THE HAZARD LAMPS
  • Ignition OFF.
  • Activate the hazard warning function and observe the turn signal lamps.

Do all turn signal lamps flash and then turn off?
Yes GO to C5
No CHECK the inoperative turn signal lamps.
REFER TO: Turn Signal and Hazard Lamps (417-01 Exterior Lighting, Diagnosis and Testing).
C5 CHECK THE RKE (REMOTE KEYLESS ENTRY) TRANSMITTER FUNCTION
  • Using the RKE transmitter, lock and unlock the doors.

Do the doors lock and unlock?
Yes GO to C6
No CHECK the inoperative RKE transmitter.
REFER TO: Locks, Latches and Entry Systems (501-14 Handles, Locks, Latches and Entry Systems, Diagnosis and Testing).
C6 CHECK THE BCM (BODY CONTROL MODULE) FOR PROPER OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect the BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

No horn sound during alarm activation (anti-theft alarm horn)


For circuit and connector information, refer to Wiring Diagrams Cell 117.

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).

Possible Causes

  • Wiring, Terminals or Connectors
  • Anti-theft alarm horn
  • BCM

DIAGNOSTIC TEST D: NO SOUND DURING ALARM ACTIVATION (ANTI-THEFT ALARM HORN SOUND)
D1 CHECK THE VOLTAGE ON THE ANTI-THEFT ALARM SIGNAL USING THE BCM (BODY CONTROL MODULE) ANTI-THEFT ALARM SIGNAL (ANTITHFT_HRN) PID (PARAMETER IDENTIFICATION)
  • Ignition OFF.
  • Disconnect the anti-theft alarm horn C4380.
  • Connect:
    Click to display connectors
    Positive lead Measurement/Action Negative lead
    C4380-1 Ground
  • The ignition is on.
  • Using the diagnostic scan tool, view the BCM parameter identification (PID) data.
  • Using a diagnostic scanner, command the BCM ANTITHFT_HRN PID on and off.

Does the indicator lamp illuminate when the anti-theft horn is activated?
Yes INSTALL a new anti-theft alarm horn.
No GO to D2
D2 CHECK THE ANTI-THEFT ALARM SIGNAL CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect C2280C.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C4380-1 Ground

Is the resistance greater than 10000 Ohms?
Yes GO to D3
No REPAIR the circuit.
D3 CHECK THE ANTI-THEFT ALARM SIGNAL CIRCUIT FOR AN OPEN
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C4380-1 C2280C-11

Is the resistance less than 3 ohms?
Yes GO to D4
No REPAIR the circuit.
D4 CHECK THE BCM (BODY CONTROL MODULE) OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect all BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

P254F:00


For circuit and connector information, refer to Wiring Diagrams Cell 117.

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).


DTC Fault Trigger Conditions


Trouble Code Description Fault Trigger Conditions
P254F:00 Hood Switch: General Electrical Malfunction Sets when the BCM detects an open in the hood ajar switch input during the self-test.

Possible Causes

  • Wiring, Terminals or Connectors
  • Hood Latch
  • BCM

Visual Inspection and Preliminary Diagnosis

  • Inspect the hood latch for damage.

DIAGNOSTIC TEST E: P254F:00
E1 DISCONNECT THE HOOD AJAR SWITCH
  • Hood Ajar Switch C127.
  • The ignition is on.
  • Connect:
    Click to display connectors
    Positive lead Measurement/Action Negative lead
    C127-2 C127-1
  • Using a scan tool, perform the BCM self-test.

Is DTC P254F:00 still present?
Yes REMOVE the fuse jumper. GO to E2.
No REMOVE the fusible link. INSTALL a new hood latch.
REFER TO: Hood Latch (501-14 Handles, Locks, Latches and Entry Systems, Removal and Installation).
E2 CHECK THE HOOD AJAR SWITCH GROUND CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C127-1 Ground

Is the resistance less than 3 ohms?
Yes GO to E3
No REPAIR the circuit.
E3 CHECK THE HOOD AJAR SWITCH INPUT CIRCUIT FOR AN OPEN
  • Disconnect C2280D.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C127-2 C2280D-10

Is the resistance less than 3 ohms?
Yes GO to E4
No REPAIR the circuit.
E4 CHECK THE BCM (BODY CONTROL MODULE) OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect the BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

B112K:87


For circuit and connector information, refer to Wiring Diagrams Cell 112.

Normal Operation and Fault Symptoms


REFER TO: Perimeter Anti-Theft Alarm - System Operation and Component Description (419-01A Perimeter Anti-Theft Alarm, Description and Operation).


DTC Fault Trigger Conditions


Trouble Code Description Fault Trigger Conditions
B112K:87 Interior Motion Sensor: No Message Sets when the BCM loses communication with the intrusion sensor.

Possible Causes

  • Wiring, Terminals or Connectors
  • Intrusion Sensor
  • BCM

DIAGNOSTIC TEST F: B112C:87
F1 CHECK THE INTRUSION SENSOR VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Disconnect the intrusion sensor C9800.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C9800-3 Ground

Is the voltage greater than 10 volts?
Yes GO to F2
No REPAIR the circuit.
F2 CHECK THE INTRUSION SENSOR GROUND CIRCUIT FOR AN OPEN
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C9800-1 Ground

Is the resistance less than 3 ohms?
Yes GO to F3
No REPAIR the circuit.
F3 CHECK THE INTRUSION SENSOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO VOLTAGE
  • Disconnect C2280G.
  • The ignition is on.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C9800-2 Ground

Is there voltage present?
Yes REPAIR the circuit.
No GO to F4
F4 CHECK THE INTRUSION SENSOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C9800-2 Ground

Is the resistance greater than 10000 Ohms?
Yes GO to F5
No REPAIR the circuit.
F5 CHECK THE INTRUSION SENSOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR AN OPEN
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C9800-2 C2280G-24

Is the resistance less than 3 ohms?
Yes INSTALL a new intrusion sensor. CHECK the system for normal operation.
If the concern persists, GO to F6.
No REPAIR the circuit.
F6 CHECK THE BCM (BODY CONTROL MODULE) FOR PROPER OPERATION
  • Disconnect and inspect all BCM connectors.
  • Repair:
    • corrosion (install new connector or terminals - clean module pins)
    • damaged or bent pins - install new terminals/pins
    • backed-out pins - install new pins as necessary
  • Reconnect the BCM connectors. Make sure they are fully seated and locked.
  • 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, STOP this test and FOLLOW the TSB instructions. If no TSBs apply to this concern, INSTALL a new BCM.
REFER TO: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
No The system is currently operating correctly. The concern may have been caused by module connections. ADDRESS the root cause of any connector or terminal issues.

Test yourself

A quick Ford Fiesta quiz: every answer comes with an explanation and a link to the manual page.