Ford Fiesta Quiz
Lighting

Brake Lamps. Diagnosis and Testing

In this manual: Lighting
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
~8min read

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

DTC Chart: BCM

DTC Chart


BCM Description Action
C1A96:24 Stop Lamp Switch: Signal High GO to Pinpoint Test C

Symptom Chart

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

Symptom Chart: Stop Lamps

Symptom Chart


Condition Possible Sources Action
Module Does Not Respond to Diagnostic Scan Tool
  • Fuse
  • Wiring, Terminals or Connectors
  • Module
REFER TO: Communication Network (418-00 Communication Network, Diagnosis and Testing).
All brake lamps inoperative Refer to Pinpoint Test GO to Pinpoint Test A
One or more brake lamps inoperative Refer to Pinpoint Test GO to Pinpoint Test B
Brake lamps on constantly Refer to Pinpoint Test GO to Pinpoint Test C

Pinpoint Tests

All brake lamps inoperative


For circuit and connector information, refer to Wiring Diagrams Cell 90.

Normal Operation and Fault Symptoms


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

Possible Sources

  • Fuse
  • Wiring, Terminals or Connectors
  • Stop Lamp Switch

Visual Inspection and Preliminary Diagnosis

  • Make sure that CJB fuse 18 (10A) is good.

DIAGNOSTIC TEST A: ALL BRAKE LAMPS INOPERATIVE
A1 CHECK THE BRAKE LAMP SWITCH VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
  • Ignition OFF.
  • Disconnect: Brake lamp switch C2314.
  • Action:
    Click to display the connectors
    Positive lead Measurement/Action Negative lead
    C2314-1 Ground

Is the voltage greater than 11 volts?
Yes GO to A2
No CHECK CJB fuse 18 (10A) is good. If OK, REPAIR the circuit. If not OK, REFER TO the Wiring Diagrams Manual to determine possible causes of the short.
A2 BRAKE LAMP SWITCH BYPASS
  • Connect a fused jumper wire:
    Click to display connectors
    Positive lead Measurement/Action Negative lead
    C2314-1 C2314-2
  • The ignition is on.

Do the stoplamps illuminate?
Yes REMOVE the jumper wire. INSTALL a new brake lamp switch.
REFER TO: Brake Lamp Switch (417-01 Exterior Lighting, Removal and Installation).
No REMOVE the jumper wire. REPAIR the brake lamp switch output circuit for an open.

One or more brake lamps inoperative


For circuit and connector information, refer to Wiring Diagrams Cell 90.

Normal Operation and Fault Symptoms


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

Possible Sources

  • Wiring, Terminals or Connectors
  • Lamp
  • High Mounted Stop Lamp

DIAGNOSTIC TEST B: ONE OR MORE BRAKE LAMPS INOPERATIVE
B1 IDENTIFY THE INOPERATIVE BRAKE LAMP
  • The ignition is on.
  • Depress the brake pedal and observe the stop lamps.

Are all brake lamps inoperative?
Yes GO to Pinpoint Test A
No For the center high-mounted stop lamp, GO TO B2.
For the rear brake lamp, GO TO B4.
B2 CHECK THE CENTER HIGH-MOUNTED STOP LAMP VOLTAGE
  • Ignition OFF.
  • Disconnect: Center high-mounted stop lamp C904 (4-door vehicles).
  • Disconnect: Center high-mounted stop lamp C9040 (5-door vehicles).
  • The ignition is on.
  • While depressing the brake pedal, measure:
    Click to display connectors

    4-door vehicles


    Positive lead Measurement/Action Negative lead
    C904-1 Ground

    Click to display the connectors

    5-door vehicles


    Positive lead Measurement/Action Negative lead
    C9040-1 Ground

Is the voltage greater than 11 volts?
Yes GO to B3
No REPAIR the center high-mounted stop lamp feed circuit for an open.
B3 CHECK THE CENTER HIGH-MOUNTED STOP LAMP GROUND CIRCUIT FOR AN OPEN
  • While depressing the brake pedal, measure:
    Click to display connectors

    4-door vehicles


    Positive lead Measurement/Action Negative lead
    C904-1 C904-2

    Click to display the connectors

    5-door vehicles


    Positive lead Measurement/Action Negative lead
    C9040-1 C9040-2

Is the voltage greater than 11 volts?
Yes INSTALL a new high-mounted stoplamp.
REFER to: High-Mounted Stoplamp (417-01 Exterior Lighting, Removal and Installation).
No REPAIR the circuit.
B4 CHECK THE VOLTAGE AT THE REAR LAMP ASSEMBLY
  • Ignition OFF.
  • Disconnect: Inoperative left rear lamp C412 (4-door) or right rear lamp C415.
  • Disconnect: 5-door inoperative Left Back-Up Lamp C414 or Right Back-Up Lamp C417.
  • The ignition is on.
  • While depressing the brake pedal, measure:
    Click to display connectors

    4-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C412-1 Ground

    Click to display the connectors

    4-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C415-1 Ground

    Click to display the connectors

    5-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C414-1 Ground

    Click to display the connectors

    5-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C417-1 Ground

Is the voltage greater than 11 volts?
Yes GO to B8
No For 4-door vehicles, GO TO B5.
For 5-door vehicles: REPAIR the stop lamp feed circuit for an open.
B5 REPEAT ON-DEMAND SELF-TEST AND CHECK THE VOLTAGE AT THE REAR LAMP ASSEMBLY
  • Using a scan tool, perform the BCM self-test.
  • Clear the diagnostic trouble codes (DTCs) and repeat the self-test (required to enable the lamp output driver).
  • Ignition OFF.
  • The ignition is on.
  • While depressing the brake pedal, measure:
    Click to display connectors

    4-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C412-1 Ground

    Click to display the connectors

    4-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C415-1 Ground

Is the voltage greater than 11 volts?
Yes INSTALL a new bulb.
REFER TO: Rear Lamp Bulb (417-01 Exterior Lighting, Removal and Installation).
CLEAR the diagnostic trouble codes (DTCs) and REPEAT the self-test (required to enable the lamp output driver).
No GO to B6
B6 CHECK THE STOP/TURN LAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
  • Ignition OFF.
  • Disconnect: BCM C2280C.
  • Action:
    Click to display the connectors

    4-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C412-1 Ground

    Click to display the connectors

    4-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C415-1 Ground

Is the resistance greater than 10000 Ohms?
Yes GO to B7
No REPAIR the circuit. CLEAR the diagnostic trouble codes (DTCs) and REPEAT the self-test (required to enable the lamp output driver).
B7 CHECK THE STOP/TURN LAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
  • Action:
    Click to display the connectors

    4-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C412-1 C2280C-12

    Click to display the connectors

    4-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C415-1 C2280C-13

Is the resistance less than 3 ohms?
Yes GO to B9
No REPAIR the circuit.
B8 CHECK THE REAR BRAKE LAMP GROUND CIRCUIT FOR AN OPEN
  • While depressing the brake pedal, measure:
    Click to display connectors

    4-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C412-1 C412-4

    Click to display the connectors

    4-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C415-1 C415-4

    Click to display the connectors

    5-door LH tail lamp


    Positive lead Measurement/Action Negative lead
    C414-1 C414-6

    Click to display the connectors

    5-door RH tail lamp


    Positive lead Measurement/Action Negative lead
    C417-1 C417-6

Is the voltage greater than 11 volts?
Yes On 4-door vehicles, INSTALL a new lamp.
REFER TO: Rear Lamp Bulb (417-01 Exterior Lighting, Removal and Installation). On 5-door vehicles, CHECK that the lamp is good. If OK, REPAIR or INSTALL a new rear lamp harness connector. If not OK, INSTALL a new bulb.
REFER TO: Rear Lamp Bulb (417-01 Exterior Lighting, Removal and Installation).
No REPAIR the circuit.
B9 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.

Brake lamps on constantly


For circuit and connector information, refer to Wiring Diagrams Cell 90.

Normal Operation and Fault Symptoms


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


DTC Fault Trigger Conditions


Trouble Code Description Fault Trigger Conditions
C1A96:24 Stop Lamp Switch: Signal High Diagnostic trouble code that is set on demand when the BCM detects voltage at the brake lamp switch input during the BCM self-test.

Possible Sources

  • Wiring, Terminals or Connectors
  • Stop Lamp Switch
  • PCM

DIAGNOSTIC TEST C: BRAKE LAMPS ON CONSTANTLY
C1 CHECK THE BRAKE LAMP SWITCH
  • Ignition OFF.
  • Disconnect: Brake lamp switch C2314.
  • The ignition is on.

Do the stoplamps remain illuminated?
Yes GO to C2
No INSTALL a new brake switch.
Refer to: Brake Switch (417-01 Exterior Lighting, Removal and Installation).
C2 CHECK THE PCM (POWERTRAIN CONTROL MODULE)
  • Ignition OFF.
  • Disconnect: PCM C175B (1.6 L TIVCT).
  • Disconnect: PCM C1915B (1.6 L EcoBoost).
  • The ignition is on.

Do the stoplamps remain illuminated?
Yes REPAIR the brake lamp switch output circuit for a short to battery voltage.
No GO to C3
C3 CHECK THE PCM (POWERTRAIN CONTROL MODULE) FOR CORRECT OPERATION
  • Disconnect and inspect all PCM 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
  • Connect the PCM 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,
Click here to access the guided routine (PCM).
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.