Ford Fiesta Manuals

Ford Fiesta: Exterior Lighting / Autolamps. Diagnosis and Testing

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

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).

DTC Chart: BCM

  BCM DTC Chart


  DTC Description Action
B1A85:21 Ambient Light Sensor: Signal Amplitude < Minimum   GO to Pinpoint Test B
B1A85:22 Ambient Light Sensor: Signal Amplitude > Maximum   GO to Pinpoint Test B

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: Autolamps

  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).
The autolamps are inoperative Refer to the Pinpoint Test   GO to Pinpoint Test A
The autolamps are on continuously Refer to the Pinpoint Test   GO to Pinpoint Test B

Pinpoint Tests

The Autolamps Are Inoperative


Refer to Wiring Diagrams Cell 71 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

  • Light sensor
  • Headlamp switch
  • BCM

PINPOINT TEST A: THE AUTOLAMPS ARE INOPERATIVE
A1 CHECK FOR VOLTAGE TO THE LIGHT SENSOR
  • Ignition OFF.
  • Disconnect: Light Sensor C2360 (EATC ).
  • Disconnect: Light Sensor C287 (EMTC ).
  • Ignition ON.
  • Place the headlamp switch in the autolamps on position.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is the voltage approximately 5 volts?
Yes INSTALL a new light sensor.
No GO to A2

A2 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.


The Autolamps Are On Continuously


Refer to Wiring Diagrams Cell 71 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
B1A85:21 Ambient Light Sensor: Signal Amplitude < Minimum A continuous memory DTC that sets when the BCM detects a short to ground from the light sensor input circuit.
B1A85:22 Ambient Light Sensor: Signal Amplitude > Maximum A continuous memory DTC that sets when the BCM detects an open or short to voltage from the light sensor input circuit.

Possible Sources

  • Wiring, terminals or connectors
  • Light sensor
  • Headlamp switch
  • BCM

Visual Inspection and Diagnostic Pre-checks

  • Inspect the headlamp switch for damage.
  • Inspect the light sensor for damage.

PINPOINT TEST B: THE AUTOLAMPS ARE ON CONTINUOUSLY
B1 CHECK FOR BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODE (DTCS)
  • Ignition ON.
  • Using a diagnostic scan tool, perform the BCM self-test.

Is DTC B1A85:21 or B1A85:22 present?
Yes For DTC B1A85:21, GO to B3
For DTC B1A85:22, GO to B5
No GO to B2

B2 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (NO DTC (DIAGNOSTIC TROUBLE CODE) )
  • Ignition OFF.
  • Disconnect: Light Sensor C2360 (EATC ).
  • Disconnect: Light Sensor C287 (EMTC ).
  • Ignition ON.
  • Place the headlamp switch in the autolamps on position.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is the voltage approximately 5 volts?
Yes INSTALL a new light sensor.
No GO to B10

B3 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC (DIAGNOSTIC TROUBLE CODE) B1A85:21)
  • Ignition OFF.
  • Disconnect: Light Sensor C2360 (EATC ).
  • Disconnect: Light Sensor C287 (EMTC ).
  • Ignition ON.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is the voltage approximately 5 volts?
Yes INSTALL a new light sensor.
No GO to B4

B4 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect: BCM C2280E.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is the resistance greater than 10,000 ohms?
Yes GO to B10
No REPAIR the circuit.

B5 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC (DIAGNOSTIC TROUBLE CODE) B1A85:22)
  • Ignition OFF.
  • Disconnect: Light Sensor C2360 (EATC ).
  • Disconnect: Light Sensor C287 (EMTC ).
  • Ignition ON.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is the voltage approximately 5 volts?
Yes GO to B6
No GO to B8

B6 CHECK THE LIGHT SENSOR
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   C2360-5

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   C287-5

Is the voltage approximately 5 volts?
Yes INSTALL a new light sensor.
No GO to B7

B7 CHECK THE LIGHT SENSOR GROUND CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Disconnect: BCM C2280E.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-5   C2280E-22

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-5   C2280E-22

Is the resistance less than 3 ohms?
Yes GO to B10
No REPAIR the circuit.

B8 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO VOLTAGE
  • Ignition OFF.
  • Disconnect: BCM C2280E.
  • Ignition ON.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   Ground

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   Ground

Is any voltage present?
Yes REPAIR the circuit.
No GO to B9

B9 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Measure:
    Click to display connectors

      For vehicles equipped with EATC


    Positive Lead Measurement / Action Negative Lead
      C2360-4   C2280E-10

    Click to display connectors

      For vehicles equipped with EMTC


    Positive Lead Measurement / Action Negative Lead
      C287-4   C2280E-10

Is the resistance less than 3 ohms?
Yes GO to B10
No REPAIR the circuit.

B10 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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