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Home >> Ford >> 2021 >> Mustang Mach 1, Automatic Trans >> Repair and Diagnosis >> Electrical >> Gauges >> Instrumentation, Message Center And Warning Chimes (2 Of 2) >> Diagnosis And Testing >> Instrumentation, Message Center and Warning Chimes >> Pinpoint Tests >> Pinpoint Test Q: The Brake Warning Indicator Is Never On

Pinpoint Test Q: The Brake Warning Indicator Is Never On

  1. Normal Operation and Fault Conditions 

    See Brake Warning Indicator and ABS/Brake/Stability-Traction Control System Indication descriptions and see Brake Fluid Level Switch component description. REFER to: Instrument Panel Cluster (IPC) - System Operation and Component Description .

    If the brake (red) warning indicator request, brake fluid level low message request or parking brake status messages are missing or invalid for less than 5 seconds, the IPC defaults the ABS warning indicator to the last indication state (on or off), based upon the last message received.

    Possible Sources 

    • Brake fluid level switch
    • Parking brake system concern
    • BCM
    • GWM concern
    • IPC

    Visual Inspection and Pre-checks 

    • Inspect the brake fluid level switch for signs of any external damage.
    • Inspect the wiring harness for signs of a pinched harness causing a shorted circuit.

  2. Q1 PERFORM THE IPC (INSTRUMENT PANEL CLUSTER) INDICATOR LAMP CONTROL ACTIVE COMMAND USING A DIAGNOSTIC SCAN TOOL

    • Ignition ON.

    • Using a diagnostic scan tool, view the IPC Parameter Identifications (PIDs).

    • Select the IPC brake warning indicator (PBA_LMP) PID.

    • Command the brake warning indicator on then off. Observe the brake warning indicator.

    Does the brake warning indicator turn on when commanded on and turn off when commanded off? 

    Yes  GO to  Q2
    No  INSTALL a new IPC. Refer to Instrument Panel Cluster (IPC) .

  3. Q2 CHECK THE GWM (GATEWAY MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, check the GWM Continuous Memory Diagnostic Trouble Codes (CMDTCs).

    Are any Diagnostic Trouble Codes (DTCs) recorded? 

    Yes  REFER to: Communications Network
    No  GO to  Q3

  4. Q3 DETERMINE IF THE BRAKE WARNING INDICATOR OPERATES WITH THE PARKING BRAKE APPLIED

    • Apply the parking brake while monitoring the brake warning indicator.

    Does the brake warning indicator illuminate? 

    Yes  GO to  Q7
    No  GO to  Q4

  5. Q4 CHECK THE PARKING BRAKE POSITION SWITCH

    • Ignition OFF.

    • Disconnect Parking Brake Position Switch C306.

    • Connect a fused jumper wire:
      Lead 1 Measurement / Action Lead 2
      C306-1
      GFD604414Courtesy of FORD MOTOR COMPANY
      		 C306-2

    • Ignition ON.

    Does the brake warning indicator illuminate? 

    Yes  REMOVE the fused jumper wire. INSTALL a new parking brake position switch.
    No  REMOVE the fused jumper wire. GO to  Q5

  6. Q5 CHECK THE PARKING BRAKE POSITION SWITCH GROUND CIRCUIT FOR AN OPEN

    • Ignition OFF.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C306-2
      GFD604413Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms? 

    Yes  GO to  Q6
    No  REPAIR the circuit.

  7. Q6 CHECK THE PARKING BRAKE WARNING INDICATOR SIGNAL CIRCUIT FOR AN OPEN

    • Disconnect BCM C2280E.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C306-1
      GFD604413Courtesy of FORD MOTOR COMPANY
      		 C2280E-47

    Is the resistance less than 3 ohms? 

    Yes  GO to  Q8
    No  REPAIR the circuit.

  8. Q7 CHECK THE BRAKE FLUID LEVEL SWITCH OPERATION

    NOTE: Verify the brake fluid level is low enough to turn on the brake warning indicator or has been reported low enough to turn on the brake warning indicator.

    • Ignition OFF.

    • Disconnect Brake Fluid Level Switch C124.

    • Ignition ON.

    • Wait one minute.

    Does the brake warning indicator illuminate? 

    Yes  If the brake fluid level is currently low or has been reported low, INSTALL a new brake fluid reservoir or master cylinder as required. REFER to: Brake Master Cylinder - 2.3L EcoBoost (201kW/273PS)/2.3L EcoBoost (213kW/290PS) (N3)
    If the brake fluid level is not currently low or has not been reported low, the system is operating correctly at this time.
    No  GO to  Q8

  9. Q8 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION

    • Ignition OFF.

    • 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 service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new BCM. Refer to Body Control Module (BCM) .
    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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