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Normal Operation and Fault Conditions

With the ignition ON, the PCM sends messages to the ABS module through the GWM over the HS-CAN. If the ABS module does not receive these messages within a certain time frame (usually less than 1 second), the ABS module sets DTCs. This can be due to a PCM failure, a GWM failure, a circuit failure on the network or an excessive load on the network. For information on the messages sent to the ABS module by the PCM, refer to the Network Message Chart in  Anti-Lock Brake System (ABS) And Stability Control  . 

PPT AI ABS MODULE DTC FAULT TRIGGER CONDITIONS

DTC Description Fault Setting Conditions
U0100:00 Lost Communication With ECM/PCM "A": No Sub Type Information This DTC sets if the ABS module does not receive any messages from the PCM.
U0401:00 Invalid Data Received From ECM/PCM "A": No Sub Type Information This DTC sets in continuous memory if the brake pedal position message, driven wheel torque message or the accelerator pedal position message from the PCM (sent through the GWM) contains invalid information.

Possible Causes 

Fig 1: Antilock Braking System (ABS) Module Connector - C135
G11681952Courtesy of FORD MOTOR CO.

Harness Side

  1. AI1: CHECK THE PCM COMMUNICATION 
    • Ignition ON, engine OFF.
    • Press the Read Vehicle Information button to view the results of the modules communicating on the network.
    • Retrieve the continuous memory DTCs.
    • Does the PCM pass the Network Test? 
      Yes No
      Go to  AI2. DIAGNOSE the scan tool does not communicate with the PCM or GWM. REFER to Module Communications Network .
  2. AI2: CHECK THE GWM COMMUNICATION 
    • Ignition ON, engine OFF.
    • Press the Read Vehicle Information button to view the results of the modules communicating on the network.
    • Retrieve the continuous memory DTCs.
    • Does the GWM pass the Network Test? 
      Yes No
      Go to  AI3. DIAGNOSE the scan tool does not communicate with the PCM or GWM. REFER to Module Communications Network .
  3. AI3: RECHECK THE ABS MODULE FOR THE LOST COMMUNICATION DTC 
    • Carry out the ABS self-test.
    • Clear the ABS DTCs.
    • Ignition OFF.
    • Ignition ON, engine OFF.
    • Carry out the ABS self-test.
    • Is DTC U0100:xx, U0104:xx, U0401:xx or U0405:xx still present? 
      Yes No
      Go to  AI4. The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.
  4. AI4: REVIEW THE ABS MODULE SELF-TEST FOR VOLTAGE-RELATED DTCS 
    • Review the results from the ABS module self-test.
    • Is DTC U3003:16 or U3003:17 present? 
      Yes No
      For DTC U3003:16, Go to PINPOINT TEST A .
      For DTC U3003:17, Go to PINPOINT TEST F .      		 Go to  AI5.
  5. AI5: CHECK FOR GWM DTCS 
  6. AI6: CHECK FOR PCM DTCS 
    • Carry out the PCM KOEO self-test.
    • Are any DTCs present? 
      Yes No
      DIAGNOSE the PCM DTC. REFER to the appropriate Diagnosis and Testing in the appropriate Electronic Engine Controls System article. Go to  AI7.
  7. AI7: CHECK FOR OTHER CAUSES OF COMMUNICATION NETWORK CONCERN 
    NOTE: If new modules were installed prior to the DTC being set, the module configuration can be incorrectly set during the PMI or the PMI may not have been carried out.
    • Check the vehicle service history for recent service actions related to the PCM or ABS module. If recent service history is found:
      • Verify the correct replacement module was installed - HVBOM may be used to verify correct part fitment.
      • Verify the configuration of replacement module was correct - re-configure the module using as-built data if prior configuration is suspect.
      • Verify the module was not obtained from a like vehicle and installed into customer vehicle - return the swapped module to source vehicle and obtain new replacement module.
    • Operate the system and determine if the observable symptom is still present.
    • Is the observable symptom still present? 
      Yes No
      Go to  AI8. The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration.
  8. AI8: CHECK FOR COMMUNICATION DTCS SET IN OTHER MODULES 
    • Retrieve the continuous memory DTCs.
    • Is DTC U0100:xx, U0104:xx, U0401:xx or U0405:xx set in 1 or more modules in addition to the ABS module? 
      Yes No
      Go to  AI9. Go to  AI10.
  9. AI9: CHECK FOR CORRECT PCM OPERATION 
    • Ignition OFF.
      NOTE: The battery must be removed to access the ABS module electrical connector.
    • Remove the battery. REFER to Charging System (Battery, Battery Mounting And Battery Cables) .
    • PCM_B connector disconnected.
    • PCM_E connector disconnected.
    • GWM connector disconnected.
    • ABS Module connector disconnected. (C135)
    • 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
    • Connect all in-line electrical connectors between the ABS module and the PCM. Make sure the connectors seat and latch correctly.
    • ABS Module connector connected. (C135) Make sure the connector seats and latches correctly.
    • GWM connector connected. Make sure the connector seats and latches correctly.
    • PCM_E connector connected. Make sure the connector seats and latches correctly.
    • PCM_B connector connected.
    • Install the battery. REFER to Charging System (Battery, Battery Mounting And Battery Cables) .
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 
      Yes No
      INSTALL a new PCM.
      CHECK OASIS for any applicable 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 PCM.
      REFER to the appropriate Electronic Engine Controls System article.      		 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.
  10. AI10: CHECK FOR CORRECT ABS MODULE OPERATION 
    • Ignition OFF.
      NOTE: The battery must be removed to access the ABS module electrical connector.
    • Remove the battery. REFER to Charging System (Battery, Battery Mounting And Battery Cables) .
    • ABS Module connector disconnected. (C135)
    • GWM connector disconnected.
    • PCM_B connector disconnected.
    • PCM_E connector disconnected.
    • 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
    • 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.
    • PCM_B connector connected. Make sure the connector seats and latches correctly.
    • GWM connector connected. 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 Charging System (Battery, Battery Mounting And Battery Cables) .
    • 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 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 the ABS module Removal and Installation procedure in Anti-Lock Brake System (ABS) And Stability Control .
      ORDER a replacement ABS module and INCLUDE the RVC form.
      If this is a Ford repair, INCLUDE the RVC on the warranty claim form.
      When complete, SELECT the "X" in the top right corner to CLOSE this procedure.      		 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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