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Home >> Ford >> 2022 >> E-Transit Van Cargo Extended >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> 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

  1. NOTE: Unless instructed otherwise, carry out all pinpoint tests without  a trailer connected to the vehicle.

    Refer to TRAILER/CAMPER ADAPTER for schematic and connector information.

    Normal Operation and Fault Conditions 

    The braking energy provided to the trailer is modulated with a PWM signal which varies between 0 volts and battery voltage, the higher the duty cycle the more braking power available. The TBM varies the PWM signal based on various inputs such as vehicle speed, the manual slider switch and the gain buttons. With the vehicle stationary and with the manual slider switch fully to the left with a gain of 10, there should be more than 11 volts supplied to the trailer tow connector.

    The TBM receives stoplamp switch information from the PCM over the HS-CAN, the TBM receives additional information from the ABS module over the HS-CAN. If there is a problem in the ABS module preventing this information from being sent to the TBM, the TBM enters a limited operating mode. The TBM receives fused battery voltage from the AJB.

    The trailer brake system only works with electric-magnet actuated drum type brakes and electric over hydraulic brakes. If the trailer is equipped with a different style of brakes or if the trailer is not equipped with brakes, the system does not function.

    Possible Sources 

    • Fuse
    • Wiring, terminals or connectors
    • TBM
    • Trailer

    Visual Inspection and Pre-checks 

    • Make sure AJB fuses 71 (30A) and 50 (10A) are OK.
    • Make sure the trailer brakes are electric-magnet actuated drum type brakes.

    NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

  2. A1 VERIFY VEHICLE STOPLAMP OPERATION

    • Ignition ON.

    • Monitor the vehicle stoplamps while pressing and releasing the brake pedal.

    Do the vehicle stoplamps operate correctly? 

    Yes  GO to  A4
    No  GO to  A2

  3. A2 CHECK THE PCM (POWERTRAIN CONTROL MODULE) BRAKE PEDAL POSITION (BOO1) PID (PARAMETER IDENTIFICATION)

    • Using a diagnostic scan tool, monitor the PCM BOO1 PID while pressing and releasing the brake pedal.

    Does the BOO1 PID display ON with the brake pedal pressed and OFF with the brake pedal released? 

    Yes  GO to  A3
    No  DIAGNOSE the vehicle stoplamps. REFER to: STOPLAMPS .

  4. A3 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) BRAKE ON/OFF (BOO_TBC) PID (PARAMETER IDENTIFICATION)

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

    Does the BOO_TBC PID display "Active" with the brake pedal pressed and "Inactive" with the brake pedal released? 

    Yes  GO to  A4
    No  The concern is mostly likely caused by a network concern. DIAGNOSE the PCM communication concern. REFER to: COMMUNICATIONS NETWORK .

  5. A4 CHECK FOR PCM (POWERTRAIN CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Ignition ON.

    • Carry out the PCM KOEO self-test.

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

    Yes  DIAGNOSE all PCM Diagnostic Trouble Codes (DTCs). REFER to: appropriate Electronic Engine Controls article .
    No  GO to  A5

  6. A5 CHECK FOR ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DIAGNOSTIC TROUBLE CODES (DTCS)

    • 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  A6

  7. A6 CHECK FOR TBM (TRAILER BRAKE CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Carry out the TBM self-test.

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

    Yes  DIAGNOSE all TBM Diagnostic Trouble Codes (DTCs). GO to DTC Chart: TBM .
    No  GO to  A2

  8. A7 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) OUTPUT

    NOTE: Battery voltage must be greater than 10 volts.

    • NOTE: If the manual slider switch is held to the full left position for more than 5 minutes, the TBM automatically shuts down.

      While an assistant presses the manual slider switch fully to the left with a gain setting of 10 on the TBM, measure:

      Positive Lead Measurement / Action Negative Lead
      C4099-3
      GFD636214Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  The TBM is operating correctly. SEND the trailer to an authorized camper or trailer repair center.
    No  GO to  A8

  9. A8 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) PWM (PULSE WIDTH MODULATION) OUTPUT CIRCUIT FOR AN OPEN

    • Ignition OFF.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C307-14
      GFD636213Courtesy of FORD MOTOR COMPANY
      		 C4099-3

    Is the resistance less than 3 ohms? 

    Yes  GO to  A9
    No  REPAIR the circuit.

  10. A9 CHECK FOR CORRECT TBM (TRAILER BRAKE CONTROL MODULE) OPERATION

    • Repair:

      • corrosion (install new connector or terminal - clean module pins)
      • damaged or bent pins - install new terminals or pins
      • pushed-out pins - install new pins as necessary

    • Connect TBM C307 and make sure that it seats 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 system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
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