Possible Causes

• Network communication concern
• GWM
• PCM

Harness Side

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. Refer to Module Communications Network article

2. AI2: CHECK THE GWM COMMUNICATION 
   • Review the results of the modules communicating on the network from the previous step.
   • Did the GWM pass the Network Test? 

     Yes	No
     Go to  AI3.	DIAGNOSE the scan tool does not communicate with the GWM. Refer to Module Communications Network article

3. AI3: RECHECK THE ABS MODULE FOR THE LOST COMMUNICATION DTC 
   • Clear the ABS DTCs.
   • Ignition OFF.
   • Ignition ON, engine OFF.
   • Carry out the ABS self-test.
   • Do any of the DTCs listed in the DTC Fault Trigger Conditions table return? 

     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 
   • Carry out the GWM self-test.
   • Are any DTCs present? 

     Yes	No
     DIAGNOSE the GWM DTC. Refer to Module Communications Network article	Go to  AI6.

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 applicable Electronic Engine Controls 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 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	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 IN OTHER MODULES 
   • Ignition ON, engine OFF.
   • Retrieve the continuous memory DTCs.
   • Is DTC U0100:xx, U0101:xx, U0401:xx or U0402:xx set in 1 or more modules in addition to the ABS module? 

     Yes	No
     Go to  AI9.	Go to  AI10.

9. AI9: VERIFY PCM OPERATION 
   • Ignition OFF.
     NOTE: The battery must be removed to access the ABS module electrical connector.
   • Remove the battery. Refer to the appropriate procedure in Battery, Mounting and Cables article
10. AI10: VERIFY ABS MODULE OPERATION 
    • Ignition OFF.
      NOTE: The battery must be removed to access the ABS module electrical connector.
    • Remove the battery. Refer to the appropriate procedure in Battery, Mounting and Cables article
    • ABS Module connector disconnected. (C135)
    • GWM connector disconnected. (C2431)
11. AI11: VERIFY ABS OPERATION 
    • Ignition OFF.
      NOTE: The battery must be removed to access the ABS module electrical connector.
    • Remove the battery. Refer to the appropriate procedure in Battery, Mounting and Cables article
    • ABS Module connector disconnected. (C135)
    • GWM connector disconnected. (C2431)