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Home >> Ford >> 2003 >> Excursion 7.3 F, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1472 (Supplemental Inflatable Restraint System) >> Diagnosis And Testing >> Pinpoint Tests - Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Tests >> Pinpoint Test AL: DTC U0073 - Control Module Communication Bus Off >> Pinpoint Test Al: DTC U0073 Control Module Communication Bus Off
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Pinpoint Test Al: DTC U0073 Control Module Communication Bus Off

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough Inspection and Verification before proceeding with the pinpoint test.
  1. AL1 CHECK FOR CONTINUOUS AND ON-DEMAND DTCs 
    WARNING:
    1. Restraint system diagnostic tools are for service only. Tools must be removed prior to operating the vehicle over the road. Failure to remove restraint system diagnostic tools could result in injury and possible violation of vehicle safety standards.
    2. Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow these instructions may result in the inadvertent deployment of the safety canopy and risk of personal injury.
    3. Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.
    4. The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.
    5. Never probe the electrical connector on a safety canopy module. Doing so can result in safety canopy deployment.
    NOTE:
    1. If a seat equipped with a supplemental restraint system (SRS) component is being serviced, the SRS must be depowered.
    2. After diagnosing or repairing an SRS, the restraint system diagnostic tools must be removed before operating the vehicle over the road. 
    3. The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Enter the following diagnostic mode on the scan tool: Retrieve/Record Continuous DTCs.
    • Was DTC U0073 retrieved during the on-demand self test? 

    Yes:  This is a hard fault. The fault condition is still present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test.

    GO to  AL2.

    No:  This is an intermittent fault. The fault condition is not present at this time. GO to  AL6.

  2. AL2 CHECK THE HS-CAN CIRCUITS FOR VOLTAGE 

    Yes:  GO to  AL3.

    No:  REPAIR circuit 1908 (WH) or circuit 1909 (BK) as necessary. GO to  AL7.

  3. AL3 CHECK THE HS-CAN CIRCUITS FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Depower the system. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
    • Measure the resistance between DLC C251-6, circuit 1908 (WH), harness side and ground; and between DLC C251-14, circuit 1909 (BK), harness side and ground.
      Fig 2: Checking HS-CAN Circuits For Short To Ground
      G04659554Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,000 ohms? 

    Yes:  GO to  AL4.

    No:  REPAIR circuit 1908 (WH) or circuit 1909 (BK) as necessary. GO to  AL7.

  4. AL4 CHECK THE HS-CAN CIRCUITS BETWEEN THE RCM AND DLC C251 FOR AN OPEN 
    • Measure the resistance between RCM C310b-31, circuit 1908 (WH), harness side and DLC C251-6, circuit 1908 (WH), harness side; and between RCM C310b-3?, circuit 1909 (BK), harness side and DLC C251-14, circuit 1909 (BK), harness side.
      Fig 3: Checking HS-CAN Circuits Between RCM & DLC C251 For Open
      G04659555Courtesy of FORD MOTOR CO.
    • Are the resistances less than 0.5 ohm? 

    Yes:  GO to  AL5.

    No:  REPAIR circuit 1908 (WH) or circuit 1909 (BK). GO to  AL7.

  5. AL5 CHECK THE HS-CAN NETWORK 
    NOTE: Make sure all restraint system diagnostic tools, sensor electrical connectors and the RCM electrical connector are connected before carrying out the on-demand self test. If not, erroneous DTCs will be recorded.

    Yes:  INSTALL a new RCM. REFER to RESTRAINTS CONTROL MODULE (RCM) . GO to  AL7.

    No:  Refer to COMMUNICATIONS NETWORK for additional information. GO to  AL7.

  6. AL6 CHECK FOR AN INTERMITTENT FAULT 
    • Key in OFF position.
    • Enter the following diagnostic mode on the scan tool: On-Demand Self Test.
    • Was DTC U0073 retrieved during the on-demand self test? 

    Yes:  This is a hard fault. The fault condition is now present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. GO to  AL2.

    No:  CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to  AL7.

  7. AL7 CHECK FOR ADDITIONAL DTCs 
    • Refer to the continuous DTCs recorded during Step  AL1.
    • Were any continuous DTCs retrieved during Step   AL1 ? 

    Yes:  Do not clear any DTCs until all DTCs have been resolved. GO to the RESTRAINTS CONTROL MODULE (RCM) DIAGNOSTIC TROUBLE CODE (DTC) TABLE  for pinpoint test direction.

    No:  RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEACTIVATION AND REACTIVATION . REPOWER the system. REFER to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING . PROVE OUT the system. CLEAR all DTCs.

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