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Pinpoint Test AE: Abs Module Communication Concern With PSCM

  1. Normal Operation and Fault Conditions 

    With the ignition ON, the PSCM sends messages to the ABS module over the FD-CAN. If the ABS module does not receive these messages within the allotted time frame or if the messages contain invalid data, the module sets a DTC. This can be due to a PSCM 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 PSCM, REFER to: Anti-Lock Brake System (ABS) and Stability Control - System Operation and Component Description .

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    ABS U0131:82 Lost Communication With Power Steering Control Module 'A': Alive/Sequence Counter Incorrect/Not Updated This DTC sets when the steering pinion data messages from the PSCM contain invalid information,
    ABS U0131:83 Lost Communication With Power Steering Control Module 'A': Value Of Signal Protection Calculation Incorrect This DTC sets when the steering pinion data messages from the PSCM contain invalid information,
    ABS U0131:87 Lost Communication With Power Steering Control Module 'A': Missing Message This DTC sets when the trailer aid messages from the PSCM contain invalid information,
    ABS U0420:86 Invalid Data Received from Power Steering Control Module 'A': Signal Invalid This DTC sets when the ABS module receives messages from the PSCM, but the messages contain invalid data.

    Possible Causes 

    • Network communication concern
    • PSCM

  2. AE1 CHECK THE COMMUNICATION NETWORK

    • Ignition ON.

    • Press the Read Vehicle Information button to view the results of the modules communicating on the network.

    • Press Read Vehicle Information button to retrieve DTC's from the vehicle.
      NOTE: DTC's may be displayed from previous diagnostic actions.

    • Read the vehicle information.

    Does the PSCM pass the Network Test? 

    Yes  RETRIEVE and RECORD all PSCM DTC's. REFER to: DIAGNOSTIC TROUBLE CODE (DTC) CHART . If there are no DTC's in the PSCM, GO to  AE2
    No  DIAGNOSE the PSCM does not communicate with the diagnostic scan tool. REFER to: Communications Network in the appropriate Module Communications Network article.

  3. AE2 RECHECK THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DTCS

    • Clear the ABS DTC's.

    • Put the ABS module in sleep mode by performing the following steps:

      • With ALL doors closed, set the ignition from ON to OFF.
      • Disconnect the diagnostic scan tool.
      • Open the door, exit the vehicle and close the door.
      • Wait a minimum of 90 seconds for the ABS module to enter sleep mode.

    • Ignition ON.

    • Carry out the ABS self-test.

    Is DTC U0131:xx or U0420:xx retrieved again? 

    Yes  GO to  AE3
    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.

  4. AE3 CHECK FOR ABS (ANTI-LOCK BRAKE SYSTEM) MODULE VOLTAGE CONCERN DTCS

    • Review the results from the recorded ABS module self-test.

    Is DTC U3003:16 or U3003:17 present? 

    Yes  For DTC U3003:16: GO to Pinpoint Test A  For DTC U3003:17: GO to Pinpoint Test F 
    No  GO to  AE4

  5. AE4 CHECK THE PSCM (POWER STEERING CONTROL MODULE) FOR DTCS

    • Carry out the PSCM self-test.

    Are any PSCM DTC's present? 

    Yes  DIAGNOSE the PSCM DTC. REFER to: DIAGNOSTIC TROUBLE CODE (DTC) CHART .
    No  GO to  AE5

  6. AE5 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 PSCM or the 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  GO to  AE6
    No  The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration.

  7. AE6 VERIFY MODULE CONFIGURATION

    • Ignition ON.

    • Using As-Built Data, configure the ABS module for trailer back up assist.

    • Using As-Built Data, configure the PSCM for trailer back up assist.

    • Operate the system and determine if the observable symptom is still present.

    Is the concern still present? 

    Yes  GO to  AE7
    No  The system is operating correctly at this time. The concern may have been due to an incorrect module configuration.

  8. AE7 CHECK FOR COMMUNICATION DTCS IN OTHER MODULES

    • Ignition ON.

    • Press Read Vehicle Information button to retrieve DTC's from the vehicle.
      NOTE: DTC's may be displayed from previous diagnostic actions.

    • Read vehicle information.

    Is DTC U0131:xx or U0420:xx set in 1 or more modules in addition to the ABS module? 

    Yes  DIAGNOSE the PSCM. REFER to: DIAGNOSTIC TROUBLE CODE (DTC) CHART .
    No  GO to  AE8

  9. AE8 VERIFY ABS (ANTI-LOCK BRAKE SYSTEM) OPERATION

    • Put the ABS module in sleep mode by performing the following steps:

      • With ALL doors closed, set the ignition from ON to OFF.

      • Disconnect the diagnostic scan tool.

      • Open the door, exit the vehicle and close the door.

      • Wait a minimum of 90 seconds for the ABS module to enter sleep mode.

    • Disconnect ABS module connector C135.

    • Disconnect PSCM connector C225A.

    • Disconnect PSCM connector C225B.

    • 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 PSCM connector C225A. Make sure the connector seats and latches correctly.

    • Connect PSCM connector C225B. Make sure the connector seats and latches correctly.

    • Connect ABS connector C135. 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  CHECK OASIS for any service articles: TSB, GSB, SSM 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 EBB unit. REFER to: Electric Brake Booster (EBB) .
    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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