Normal Operation and Fault Conditions

The ABS module receives BPP switch input from the PCM through the GWM over the HS-CAN. The ABS module compares this information against wheel speed sensor input to determine if the BPP switch input is valid. As vehicle speed decreases, the ABS module looks for a change in the BPP switch input, if vehicle speed decreases but there is no change in the BPP switch, the ABS module sets a DTC. An incorrectly installed BPP switch can cause a signal plausibility concern. An implausible signal can also be created if a driver is resting one foot on the brake pedal while using the other foot to press the accelerator. 

Possible Causes 

• Wiring, terminals or connectors
• BPP switch
• Network communication concern
• PCM
• Pressing both pedals (brake and accelerator) at the same time

Visual Inspection and Diagnostic Pre-checks 

• Make sure the stoplamp switch electrical connector is connected and free of corrosion and other contaminants.
• Make sure the stoplamp switch is installed correctly.
• Make sure the stoplamp switch operates correctly.

Fig 1: Antilock Braking System (ABS) Module Connector - C135

Courtesy of FORD MOTOR CO.

Harness Side

Fig 2: Brake Pedal Position (BPP) Switch Connector - C278

Courtesy of FORD MOTOR CO.

Harness Side

1. AC1: CHECK THE STOPLAMP SWITCH AND BRAKE PEDAL ASSEMBLY INSTALLATION 
   • Inspect the stoplamp switch and brake pedal assembly. Verify there is no brake pedal pressure unintentionally applied due to incorrect stoplamp switch or brake pedal installation.
     • To verify BPP switch installation, refer to EXTERIOR LIGHTING SYSTEM .
     • To verify brake pedal installation, refer to HYDRAULIC BRAKE SYSTEM ACTUATION .
   • Is the stoplamp switch and brake pedal assembly installed correctly? 

     Yes	No
     Go to  AC2.	REINSTALL the stoplamp switch or brake pedal assembly correctly. REFER to EXTERIOR LIGHTING SYSTEM .

2. AC2: CHECK THE PCM BPP (BOO1) PID 
   • Ignition ON, engine OFF.
   • Access the PCM and monitor the BOO1 (MODE) PID.
   • Apply and release the brake pedal.
   • Does the PID reflect the brake pedal movement? 

     Yes	No
     DIAGNOSE the stoplamps. REFER to EXTERIOR LIGHTING SYSTEM .	Go to  AC3.

3. AC3: CHECK THE ABS MODULE BRAKE PRESSURE PID 
   • Access the ABS and monitor the BRKHYDPRESS (PRESS) PID.
   • Apply and release the brake pedal.
   • Does the PID read 0 PSI with the brake pedal released and then increase when the brake pedal is applied? 

     Yes	No
     Go to  AC4.	Go to PINPOINT TEST Y .

4. AC4: CHECK THE ABS MODULE BRAKE ON/OFF (BOO_ABS) PID 
   • Access the ABS and monitor the BOO_ABS (MODE) PID.
   • Apply and release the brake pedal.
   • Does the PID reflect the brake pedal movement? 

     Yes	No
     The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.	Go to  AC5.

5. AC5: CHECK FOR ABS MODULE DTCS 
   • Carry out the ABS self-test.
   • Are any lost communication with PCM, invalid data from PCM, pressure sensor, wheel speed sensor or stability control sensor DTCs present in the ABS module? 

     Yes	No
     DIAGNOSE all lost communication with PCM, invalid data from PCM, pressure sensor, wheel speed sensor or stability control sensor DTCs before diagnosing DTC C0040:xx or C0044:xx. REFER to the ABS Module DTC Chart .	Go to  AC6.

6. AC6: CHECK THE PCM FOR DTCS 
   • Carry out the PCM KOEO self-test.
   • Are any DTCs present? 

     Yes	No
     DIAGNOSE the PCM DTC. REFER to the ELECTRONIC ENGINE CONTROLS SYSTEM - 2.0L ECOBOOST (184KW/250PS) - MI4 , ELECTRONIC ENGINE CONTROLS SYSTEM - 2.7L ECOBOOST (238KW/324PS) or ELECTRONIC ENGINE CONTROLS SYSTEM - 3.5L DURATEC (212KW/278PS) .	Go to  AC7.

7. AC7: CHECK FOR CORRECT ABS MODULE TO HCU FASTENER TORQUE VALUES 
   NOTE: The battery must be removed to access the ABS module electrical connector.
   • Remove the battery. Refer to GENERAL PROCEDURES .
   • Verify all ABS module-to-HCU fasteners are tightened to their correct torque specifications.
   • Are the ABS module-to-HCU fasteners tightened correctly? 

     Yes	No
     Go to  AC8.	TIGHTEN all ABS module-to-HCU fasteners to their specified torque value. Go to  AC8.

8. AC8: CHECK FOR RETURNING ABS MODULE DTCS 
   • Install the battery. Refer to GENERAL PROCEDURES .
   • Clear the ABS DTCs.
   • Ignition OFF.
   • Ignition ON, engine OFF.
   • Carry out the ABS self-test.
   • Is DTC C0040:xx or C0044:xx still present? 

     Yes	No
     Go to  AC9.	The condition causing the concern has been repaired. RETURN the vehicle to the customer.

9. AC9: VERIFY ALL WIRING CONNECTIONS 
   • Ignition OFF.
     NOTE: The battery must be removed to access the ABS module electrical connector.
   • Remove the battery. Refer to GENERAL PROCEDURES .
   • ABS Module connector disconnected. (C135)
   • PCM_B connector disconnected. (C1381B)
   • PCM_E connector disconnected. (C1381E)
   • Disconnect all in-line electrical connectors between the ABS module and the PCM.
   • Using a good light source, inspect all disconnected electrical connectors 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	No
     Go to  AC10.	REPAIR the connector or terminals. Refer to OEM CONNECTOR REPAIR PROCEDURES , for schematic and connector information.

10. AC10: CHECK FOR CORRECT ABS MODULE OPERATION 
    • Connect all in-line electrical connectors between the ABS module and the PCM. Make sure the connectors seat and latch correctly.
    • PCM_E connector connected. (C1381E) Make sure the connector seats and latches correctly.
    • PCM_B connector connected. (C1381B) Make sure the connector seats and latches correctly.
    • ABS Module connector connected. (C135) Make sure the connector seats and latches correctly.
    • Install the battery. Refer to GENERAL PROCEDURES .
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 

      Yes

      No

      INSTALL a new ABS module. 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 TSBs address this concern, INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL . ORDER a replacement ABS module and INCLUDE the RVC on the form. If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form. When complete, SELECT the "X" in the top right corner to CLOSE this procedure and RETURN to the PTS web site.

      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. If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form. When complete, SELECT the "X" in the top right corner to CLOSE this procedure and RETURN to the PTS web site.