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: Anti-Lock Brake System-A (ABS-A) Module Connector - C135A

Courtesy of FORD MOTOR CO.

Harness Side

Fig 2: Anti-Lock Brake System-B (ABS-B) Module Connector - C135B

Courtesy of FORD MOTOR CO.

Harness Side

1. AC1: Check For ABS Module DTCs 
   • Ignition ON, engine OFF.

   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  AC2.

   • AC2: Check The PCM For DTCs 

     Carry out the PCM KOEO self-test.

   • Are any DTCs present in the PCM? 

   Yes	No
   DIAGNOSE all PCM DTCs before diagnosing DTC C0040:xx or C0044:xx. REFER to the appropriate Electronic Engine Controls article. If the scan tool cannot communication with the PCM, DIAGNOSE the no communication concern. REFER to the Module Communications Network article.	Go to  AC3.

2. AC3: CHECK THE BPP SWITCH AND BRAKE PEDAL ASSEMBLY INSTALLATION 
   • Inspect the BPP switch and brake pedal assembly. Verify there is no brake pedal pressure unintentionally applied due to incorrect BPP switch or brake pedal installation.
     • For BPP (stoplamp) switch installation, refer to the Exterior Lighting article.
     • For brake pedal installation, refer to the Hydraulic Brake Actuation article.
   • Is the stoplamp switch and brake pedal assembly installed correctly? 

   Yes	No
   Go to  AC4.	REINSTALL the brake pedal assembly or BPP switch correctly. REFER to the Hydraulic Brake Actuation article or the Exterior Lighting article.

3. AC4: 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
   Go to  AC5.	DIAGNOSE the stoplamps. REFER to the Exterior Lighting article.

4. AC5: 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 approximately 0 PSI with the brake pedal released and then increase when the brake pedal is applied? 

   Yes	No
   Go to  AC6.	GO to Pinpoint Test Y .

5. AC6: 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? 
6. AC7: Check For Correct ABS Module To HCU Fastener Torque Values 
   • 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  AC9.	TIGHTEN all ABS module-to-HCU fasteners to their specified torque value. Go to  AC8.

7. AC8: Check For Returning ABS Module DTCs 
   • Ignition ON, engine OFF.
   • Clear the ABS DTCs.
   • Ignition ON, engine OFF.
   • Test drive the vehicle, carry out at least 3 stops.

   Carry out the ABS self-test.

   • Are any of the DTCs in the DTC Fault Trigger Conditions table present and active in the ABS module? 

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

8. AC9: Verify All Wiring Connections 
   • Ignition OFF.
   • ABS_A Module connector disconnected. (C135A)
   • ABS_B Module connector disconnected. (C135B)
9. AC10: Check For Correct ABS Module Operation 
   • BPP Switch connector connected. Make sure the connector seats and latches correctly.
   • Operate the system and determine if the concern is still present.
   • Is the concern still present? 

   Yes	No
   CHECK OASIS for any applicable service articles: TSB, GSB, SSMs 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 brake pedal switch (also known as a stoplamp switch). REFER to the Exterior Lighting article.	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.

10. AC11: Check For Correct ABS Operation 
    • BPP Switch connector connected. Make sure the connector seats and latches correctly.