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Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 656 (Auxiliary Brake System) >> Diagnosis And Testing >> Auxiliary Brake System - Vehicles With: Trailer Brake Control >> Pinpoint Tests >> Pinpoint Test A : The Trailer Brakes Are Inoperative >> Pinpoint Test A : The Trailer Brakes Are Inoperative

Pinpoint Test A : The Trailer Brakes Are Inoperative

WARNING: This page is about a different car, the 2015 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

  1. A1 CHECK FOR BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Ignition ON.
    • Using a diagnostic scan tool, carry out the BCM self-test.

    Are any Diagnostic Trouble Codes (DTCs) present in the BCM? 

    Yes  DIAGNOSE all BCM Diagnostic Trouble Codes (DTCs). REFER to: Body Control Module (BCM) .
    No  GO to  A2

  2. A2 CHECK FOR ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, carry out the ABS module self-test.

    Are any Diagnostic Trouble Codes (DTCs) present in the ABS module? 

    Yes  DIAGNOSE all ABS module Diagnostic Trouble Codes (DTCs). REFER to: Anti-Lock Brake System (ABS) and Stability Control .
    No  GO to  A3

  3. A3 CHECK FOR TBM (TRAILER BRAKE CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, carry out the TBM self-test.

    Does the TBM communicate with the diagnostic scan tool? 

    Yes  If there are Diagnostic Trouble Codes (DTCs) in the TBM, DIAGNOSE all TBM Diagnostic Trouble Codes (DTCs). GO to the DTC Chart: TBM . If there are no Diagnostic Trouble Codes (DTCs) in the TBM, GO to  A4
    No  DIAGNOSE the TBM does not communicate with the diagnostic scan tool. REFER to: Communications Network .

  4. A4 CHECK THE BCM (BODY CONTROL MODULE) BRAKE SWITCH 2 (BOO_2) PID (PARAMETER IDENTIFICATION)

    • Using a diagnostic scan tool, monitor the BCM BOO_2 PID while pressing and releasing the brake pedal.

    Does the BOO_2 PID display ON with the brake pedal pressed and OFF with the brake pedal released? 

    Yes  GO to  A5
    No  DIAGNOSE the vehicle stoplamps. REFER to: Stoplamps .

  5. A5 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) BRAKE SWITCH (BRAKE_SW) PID (PARAMETER IDENTIFICATION)

    • Using a diagnostic scan tool, monitor the TBM BRAKE_SW PID while pressing and releasing the brake pedal.

    Does the BRAKE_SW PID display ON with the brake pedal pressed and OFF with the brake pedal released? 

    Yes  GO to  A8
    No  GO to  A6

  6. A6 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) BPP (BRAKE PEDAL POSITION) SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND

    • Ignition OFF.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2142-12
      GFD38391Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  A7
    No  REPAIR the circuit.

  7. A7 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) BPP (BRAKE PEDAL POSITION) SWITCH INPUT CIRCUIT FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2142-12
      GFD38391Courtesy of FORD MOTOR COMPANY
      		 C2280A-13

    Is the resistance less than 3 ohms? 

    Yes  VERIFY BCM fuse 4 (5A) is OK. If not OK, REFER to the SYSTEM WIRING DIAGRAMS article to identify the cause of the circuit short. If OK, GO to  A10
    No  REPAIR the circuit.

  8. A8 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) PWM (PULSE WIDTH MODULATION) OUTPUT CIRCUIT FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2142-14
      GFD38391Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  A9
    No  REPAIR the circuit.

  9. A9 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) PWM (PULSE WIDTH MODULATION) OUTPUT CIRCUIT FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2142-14
      GFD38391Courtesy of FORD MOTOR COMPANY
      		 C4099-3

    Is the resistance less than 3 ohms? 

    Yes  GO to  A10
    No  REPAIR the circuit.

  10. A10 VERIFY ALL WIRING CONNECTIONS

    • Using a good light source, inspect TBM C2142 and BCM C2280A for the following:
      • corrosion - install new connector or terminal and clean the module pins
      • damaged or bent pins - install new terminals or pins
      • pushed-out pins - install new pins as necessary
      • spread terminals - install new terminals as necessary

    Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals? 

    Yes  GO to  A11
    No  REPAIR the affected connectors or terminals. Refer to CONNECTOR REPAIR PROCEDURES for schematic and connector information.

  11. A11 CHECK FOR CORRECT TBM (TRAILER BRAKE CONTROL MODULE) OPERATION

    • Connect TBM C2142 , make sure it seats and latches correctly.
    • Connect BCM C2280A , make sure it seats and latches correctly.
    • Operate the system and verify 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 the TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new TBM. REFER to: Trailer Brake Control Module (TBM) .
    No  The condition that caused the concern is not present at this time. The concern is intermittent and may have been caused by a loose or corroded connector, low battery voltage or an excessive load on the HS-CAN1 or HS-CAN2.
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