Ford Fiesta Manuals

Ford Fiesta: Exterior Lighting / Fog Lamps. Diagnosis and Testing

Ford Fiesta 2014 - 2019 Service Manual / Lighting / Exterior Lighting / Fog Lamps. Diagnosis and Testing

DTC Chart: BCM

  BCM DTC Chart


  DTC Description Action
B1046:23 Front Fog Lamp Control Switch: Signal Stuck Low   GO to Pinpoint Test C
B1A78:12 Front Fog Lamp: Circuit Short To Battery   GO to Pinpoint Test A
B1A78:14 Front Fog Lamp: Circuit Short To Ground Or Open
  • If the fog lamps are inoperative, GO to Pinpoint Test A
  • If the fog lamps are always on, GO to Pinpoint Test C
U3000:49 Control Module: Internal Electronic Failure The module has permanently disabled an output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the BCM can withstand. The cause of the excessive current draw MUST be corrected before a new BCM is installed. ADDRESS all other Diagnostic Trouble Codes (DTCs) first. After the cause of the concern is corrected, INSTALL a new BCM .
REFER to: Body Control Module (BCM) (419-10 Multifunction Electronic Modules, Removal and Installation).
For additional information on BCM Field Effect Transistor (FET) protection,
REFER to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Symptom Chart(s)

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: Fog Lamps

  Symptom Chart


Condition Possible Sources Actions
A module does not respond to the diagnostic scan tool
  • Fuse
  • Wiring, terminals or connectors
  • Module
 
REFER to: Communications Network (418-00 Module Communications Network, Diagnosis and Testing).
Both front fog lamps are inoperative Refer to the Pinpoint Test   GO to Pinpoint Test A
An individual front fog lamp is inoperative Refer to the Pinpoint Test   GO to Pinpoint Test B
The front fog lamps are on continuously Refer to the Pinpoint Test   GO to Pinpoint Test C

Pinpoint Tests

Both Front Fog Lamps Are Inoperative


Refer to Wiring Diagrams Cell 86 for schematic and connector information.

Normal Operation and Fault Conditions


REFER to: Exterior Lighting - System Operation and Component Description (417-01 Exterior Lighting, Description and Operation).


  DTC Fault Trigger Conditions


  DTC Description Fault Trigger Conditions
B1A78:12 Front Fog Lamp: Circuit Short To Battery A continuous and on-demand DTC that sets when the BCM detects a short to voltage from the front fog lamp relay control circuit.
B1A78:14 Front Fog Lamp: Circuit Short To Ground Or Open A continuous and on-demand DTC that sets when the BCM detects an open or short to voltage from the front fog lamp relay control circuit.
U3000:49 Control Module: Internal Electronic Failure This DTC sets when the BCM has permanently shut down the output driver. The module has permanently disabled an output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the BCM can withstand. CORRECT the cause of the excessive current draw before installing a new BCM . For additional information on BCM Field Effect Transistor (FET) protection,
REFER to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Possible Sources

  • Fuse(s)
  • Wiring, terminals or connectors
  • Headlamp switch
  • Fog lamp relay
  • BCM

Visual Inspection and Diagnostic Pre-checks

  • Inspect the fog lamp bulbs and make sure they are OK.
  • Inspect the BJB fuses 19 (20A) and 21 (7.5A).
  • Inspect the headlamp switch for damage.

PINPOINT TEST A: BOTH FRONT FOG LAMPS ARE INOPERATIVE
A1 CHECK THE BCM (BODY CONTROL MODULE) FOG LAMP SWITCH INPUT
  • Ignition ON.
  • Place the headlamp switch in the off position.
  • Using a diagnostic scan tool, view BCM Parameter Identifications (PIDs).
  • Monitor the BCM FOG_F_SW PID .
  • Place the headlamp switch in the parking lamps on position and engage the fog lamp switch.

Does the BCM FOG_F_SW PID change from Off to On?
Yes GO to A4
No GO to A2

A2 CHECK THE FOG LAMP SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
  • Ignition OFF.
  • Disconnect: Headlamp Switch C205.
  • Disconnect: BCM C2280F.
  • Ignition ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280F-14   Ground

Is any voltage present?
Yes REPAIR the circuit.
No GO to A3

A3 CHECK THE FOG LAMP SWITCH CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280F-14   C205-5

Is the resistance less than 3 ohms?
Yes CARRY OUT the Headlamp Switch component test.
Refer to Wiring Diagrams Cell 149 for schematic and connector information. If the headlamp switch tests bad, INSTALL a new headlamp switch.
REFER to: Headlamp Switch (417-01 Exterior Lighting, Removal and Installation). If the headlamp switch tests good, GO to A10
No REPAIR the circuit.

A4 CHECK FOR BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODE (DTCS)
  • Using a diagnostic scan tool, perform the BCM self-test.

Is DTC B1A78:12 or B1A78:14 present?
Yes For DTC B1A78:12, GO to A5
For DTC B1A78:14, GO to A6
No GO to A9

A5 CHECK THE FOG LAMP RELAY ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Disconnect: BCM C2280D.
  • Ignition ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280D-14   Ground

Is any voltage present?
Yes REPAIR the circuit. CLEAR the Diagnostic Trouble Codes (DTCs) and REPEAT the self-test (required to enable the lamp output driver).
No GO to A7

A6 CHECK THE FOG LAMP RELAY ENABLE CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Disconnect: BCM C2280D.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280D-14 Fog Lamp Relay Pin 2

Is the resistance less than 3 ohms?
Yes GO to A7
No REPAIR the circuit.

A7 CHECK THE FOG LAMP RELAY
  • Ignition OFF.
  • Connect: BCM C2280D.
  • Install a known good relay for the fog lamp relay.
  • Ignition ON.
  • Place the headlamp switch in the parking lamps on position and engage the fog lamp switch.

Do the fog lamps illuminate?
Yes INSTALL a new fog lamp relay.
No For DTC B1A78:12, GO to A10
For DTC B1A78:14, GO to A8

A8 CHECK THE FOG LAMP RELAY FOR VOLTAGE TO THE COIL
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Ignition ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
    Fog Lamp Relay Pin 1   Ground

Is the voltage greater than 11 volts?
Yes GO to A10
No VERIFY the BJB fuse 21 (7.5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.

A9 CHECK THE FOG LAMP RELAY FOR VOLTAGE TO THE SWITCH
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Ignition ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
    Fog Lamp Relay Pin 5   Ground

Is the voltage greater than 11 volts?
Yes REPAIR the fog lamp relay output circuit for an open.
No VERIFY the BJB fuse 19 (20A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.

A10 CHECK FOR CORRECT 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
    • pushed-out pins – install new pins as necessary
  • Reconnect the BCM connectors. Make sure they 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.


An Individual Front Fog Lamp Is Inoperative


Refer to Wiring Diagrams Cell 86 for schematic and connector information.

Normal Operation and Fault Conditions


REFER to: Exterior Lighting - System Operation and Component Description (417-01 Exterior Lighting, Description and Operation).

Possible Sources

  • Bulb
  • Wiring, terminals or connectors

Visual Inspection and Diagnostic Pre-checks

  • Inspect the fog lamp bulb and make sure it is OK.
  • Inspect the BJB fuses 35 (10A) and 36 (10A).

PINPOINT TEST B: AN INDIVIDUAL FRONT FOG LAMP IS INOPERATIVE
B1 CHECK FOR VOLTAGE TO THE INOPERATIVE FOG LAMP
  • Ignition OFF.
  • Disconnect: Inoperative LH Fog Lamp C152 or RH Fog Lamp C162.
  • Ignition ON.
  • Place the headlamp switch in the parking lamps on position and engage the fog lamp switch.
  • Measure:
    Click to display connectors

      LH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
      C152-1   Ground

    Click to display connectors

      RH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
      C162-1   Ground

Is the voltage greater than 11 volts?
Yes GO to B3
No VERIFY the BJB fuse 35 (10A) or 36 (10A) is OK. If OK, GO to B2 If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.
GO to B2

B2 CHECK FOG LAMP FUSE VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
  • Measure:
    Click to display connectors

      LH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
    BJB Fuse 35 (10A)   Ground

    Click to display connectors

      RH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
    BJB Fuse 36 (10A)   Ground

Is the voltage greater than 11 volts?
Yes REPAIR the circuit between the fog lamp fuse and the fog lamp.
No REPAIR the circuit.

B3 CHECK FOG LAMP GROUND CIRCUIT FOR AN OPEN
  • Measure:
    Click to display connectors

      LH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
      C152-1   C152-2

    Click to display connectors

      RH Fog Lamp


    Positive Lead Measurement / Action Negative Lead
      C162-1   C162-2

Is the voltage greater than 11 volts?
Yes INSTALL a new fog lamp bulb.
REFER to: Front Fog Lamp Bulb (417-01 Exterior Lighting, Removal and Installation).
No REPAIR the circuit.


The Front Fog Lamps Are On Continuously


Refer to Wiring Diagrams Cell 86 for schematic and connector information.

Normal Operation and Fault Conditions


REFER to: Exterior Lighting - System Operation and Component Description (417-01 Exterior Lighting, Description and Operation).


  DTC Fault Trigger Conditions


  DTC Description Fault Trigger Conditions
B1046:23 Front Fog Lamp Control Switch: Signal Stuck Low A continuous and on-demand DTC that sets when the BCM detects the fog lamp switch circuit is grounded during the BCM self-test.
B1A78:14 Front Fog Lamp: Circuit Short To Ground Or Open A continuous and on-demand DTC that sets when the BCM detects an open or short to voltage from the front fog lamp relay control circuit.
U3000:49 Control Module: Internal Electronic Failure This DTC sets when the BCM has permanently shut down the output driver. The module has permanently disabled an output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the BCM can withstand. CORRECT the cause of the excessive current draw before installing a new BCM . For additional information on BCM Field Effect Transistor (FET) protection,
REFER to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Possible Sources

  • Wiring, terminals or connectors
  • Headlamp switch
  • Fog lamp relay
  • BCM

Visual Inspection and Diagnostic Pre-checks

  • Inspect the headlamp switch for damage.

PINPOINT TEST C: THE FRONT FOG LAMPS ARE ON CONTINUOUSLY
C1 CHECK BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)
  • Ignition ON.
  • Place the headlamp switch in the off position.
  • Using a diagnostic scan tool, perform the BCM self-test.

Is DTC B1046:23 or B1A78:14 present?
Yes For DTC B1046:23, GO to C2
For DTC B1A78:14, GO to C3
No GO to C5

C2 CHECK THE FOG LAMP SWITCH CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect: Headlamp Switch C205.
  • Disconnect: BCM C2280F.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
      C2280F-14   Ground

Is the resistance greater than 10,000 ohms?
Yes CARRY OUT the Headlamp Switch component test.
Refer to Wiring Diagrams Cell 149 for schematic and connector information.
If the headlamp switch tests bad, INSTALL a new headlamp switch.
REFER to: Headlamp Switch (417-01 Exterior Lighting, Removal and Installation).
If the headlamp switch tests good, GO to C6
No REPAIR the circuit.

C3 CHECK THE FOG LAMP RELAY ENABLE CIRCUIT FOR GROUND
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Ignition ON.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
    Fog Lamp Relay Pin 1 Fog Lamp Relay Pin 2

Is any voltage present?
Yes GO to C4
No GO to C6

C4 CHECK THE FOG LAMP RELAY ENABLE CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect: BCM C2280D.
  • Measure:
    Click to display connectors
    Positive Lead Measurement / Action Negative Lead
    Fog Lamp Relay Pin 2   Ground

Is the resistance greater than 10,000 ohms?
Yes REPAIR the circuit.
No GO to C6

C5 CHECK THE FOG LAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
  • Ignition OFF.
  • Disconnect: fog lamp relay.
  • Ignition ON.

Do the fog lamps continue to illuminate?
Yes REPAIR the circuit.
No INSTALL a new fog lamp relay.

C6 CHECK FOR CORRECT 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
    • pushed-out pins – install new pins as necessary
  • Reconnect the BCM connectors. Make sure they 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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