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Home >> Lincoln >> 2018 >> Navigator Select, 4WD >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> RCM Guided Routine Testing -- (2 Of 4) >> Pinpoint Tests >> Pinpoint Test AH: Lost Communication with PCM >> Possible Causes

Possible Causes

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.
NOTE: Only disconnect or reconnect SRS components when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.
NOTE: Always make sure the correct SRS component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to make sure the correct component is being installed. If an incorrect SRS component is installed, DTCs may set.
  1. AH1: VERIFY THE CONCERN 
    • Ignition ON, engine OFF.
    • Verify there is an observable symptom present.
    • Is an observable symptom present? 
      Yes No
      Go to  AH2. The system is operating normally at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.
  2. AH2: VERIFY THE SCAN TOOL COMMUNICATES WITH THE PCM 
    WARNING: Before beginning any service procedure in this article, refer to Safety Warnings in General Information article. Failure to follow this instruction may result in serious personal injury. Refer to Pyrotechnic Device Health and Safety Precautions.
    • Press the Read Vehicle Information button to view the results of the modules communicating on the network.
    • Retrieve the continuous memory DTCs.
    • Is a vehicle session established? 
      Yes No
      For OCSM, Go to  AH3.
      For RCM, Go to  AH4.
      For BECMB, Go to  AH5.
      For all others,
      No fault found.      		 DIAGNOSE no communication PCM with the diagnostic scan tool. REFER to Diagnosis and Testing in Module Communications Network article
  3. AH3: CHECK THE OCSM CMDTCS 
    • Carry out the OCS self-test.
    • Clear the OCS DTCs.
    • Wait ten seconds.
    • Carry out the OCS self-test.
    • Is DTCs U0100:00 retrieved again? 
      Yes No
      Go to  AH4. 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. AH4: CHECK THE RCM CMDTCS 
    • Carry out the RCM self-test.
    • Clear the RCM DTCs.
    • Wait ten seconds.
    • Carry out the RCM self-test.
    • Is DTCs U0100:00 retrieved again? 
      Yes No
      Go to  AH8. The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.
  5. AH5: CHECK THE BECMB CMDTCS 
    • Carry out the BECMB self-test.
    • Clear the BECMB DTCs.
    • Wait ten seconds.
    • Carry out the BECMB self-test.
    • Is DTCs U0100:87 retrieved again? 
      Yes No
      Go to  AH6. The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.
  6. AH6: CHECK FOR THE CORRECT BECMB 
    • Using the Log Viewer function of the diagnostic scan tool, retrieve and record the BECMB part number.
    • Check the recorded part number against the number listed in the Ford parts catalog.
    • Does the recorded part number match the number listed in the Ford parts catalog? 
      Yes No
      Go to  AH7. INSTALL the correct BECMB and use As-Built data when carrying out PMI. REFER to: Battery Energy Control Module B (BECMB) Supplemental Restraint System article
      Go to  AH11.
  7. AH7: VERIFY THE BECMB CONFIGURATION 
    • Carry out PMI for the BECMB. Manually enter As-Built data. Refer to the diagnostic scan tool instructions when carrying out PMI.
    • Clear the BECMB DTCs.
    • Wait 10 seconds.
    • Carry out the BECMB self-test.
    • Is DTC U0100:87 retrieved again? 
      Yes No
      Go to  AH8. Go to  AH11.
  8. AH8: CHECK FOR PCM DTCS 
    • Carry out the PCM KOEO self-test.
    • Are any DTCs present? 
      Yes No
      DIAGNOSE the PCM DTCs. REFER to the appropriate applicable Electronic Engine Controls article. For OCSM, Go to  AH9.
      For RCM, Go to  AH10.
      For BECMB, Go to  AH11.
  9. AH9: RETRIEVE THE RECORDED DTCS FROM THE OCSM SELF-TEST 
    • Carry out the OCS self-test.
    • Is DTCs U3003:16 or U3003:17 recorded? 
      Yes No
      REFER to the DTC Chart. Go to  AH11.
  10. AH10: RETRIEVE THE RECORDED DTCS FROM THE RCM SELF-TEST 
    • Carry out the RCM self-test.
    • Is DTCs U3003:16 or U3003:17 recorded? 
      Yes No
      REFER to the DTC Chart. Go to  AH11.
  11. AH11: 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, the OCSM, and the RCM. If recent service history is found:
      • verify correct replacement module was installed (HVBOM or vehicle parts build list 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 vehicle with concern (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  AH12. The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration.
  12. AH12: CHECK FOR CORRECT PCM OPERATION 
    • Ignition OFF.
    • Disconnect and inspect all the PCM and any related in-line connectors.
    • Repair:
      • corrosion (install new connectors or terminals - clean module pins)
      • damaged or bent pins - install new terminals pins
      • pushed-out pins - install new pins as necessary
    • Reconnect the PCM and any related in-line connectors. Make sure they seat and latch correctly.
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 
      Yes No
      CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSBs address this concern, INSTALL a new PCM. REFER to the Removal and Installation procedure in the appropriate Electronic Engine Controls 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.
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