Possible Causes

• 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 ABS module pass the Network Test? 

  Yes	No
  Go to  BU3.	Go to  BU2.

• 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  BU3.	DIAGNOSE the scan tool does not communicate with the GWM. REFER to the Module Communications Network article.

Carry out the ABS self-test.

• Are any DTCs present? 

  Yes	No
  DIAGNOSE the ABS module DTCs. GO to the ABS Module DTC Chart.	Go to  BU4.

Carry out the GWM self-test.

• Are any DTCs present? 

  Yes	No
  DIAGNOSE the GWM DTC. REFER to the Module Communications Network article.	Go to  BU5.

Carry out the PCM KOEO self-test.

• Are any DTCs present? 

  Yes	No
  DIAGNOSE the PCM DTC. REFER to the appropriate Electronic Engine Controls article.	Go to  BU6.

• Clear the PCM DTCs.
• Ignition OFF.
• Ignition ON, engine OFF.

  Carry out the PCM KOEO self-test.

• Are any DTCs present? 

  Yes	No
  DIAGNOSE the PCM DTC. REFER to the appropriate Electronic Engine Controls article.	Go to  BU7.

• Test drive the vehicle.
  • Carry out at least 1 ABS loose gravel acceleration and stop.
• Ignition OFF.
• Ignition ON, engine OFF.

  Carry out the PCM KOEO self-test.

• Are any DTCs present? 

  Yes	No
  For KOEO DTC P1637, SET the ignition to OFF. DISCONNECT all PCM and ABS module electrical connectors. INSPECT the connectors for signs of corrosion, bent pins, pushed-out pins and spread terminals. REPAIR as necessary. For all others, DIAGNOSE the PCM DTC. REFER to the appropriate Electronic Engine Controls article.	The system is operating correctly at this time. The concern may be caused by a loose or corroded connector.