Inspection and Verification

• 1.
  
  Verify the customer concern.

• 2.
  
  Verify the stoplamps operate correctly by pressing and releasing the brake pedal. If the stoplamps do not operate correctly, refer to Exterior Lighting . If the stoplamps operate correctly, proceed to the next step.

• 3.
  
  Verify the base brake system operates correctly. If any concerns are present, address them before continuing with any ABS concerns. Refer to Brake System General Information . If the base brake system operates correctly, proceed to the next step.

• 4.
  
  Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart 

Mechanical	Electrical
Base brake system Hydraulic Control Unit (HCU) Steering components, suspension components and tire size Tire pressure Mismatched tires Wheel and tire sizes	ABS module Battery Junction Box (BJB) fuse(s): 5 (40A) 43 (30A) 92 (10A) Brake fluid level switch Stoplamp switch Wiring, terminals or connectors Wheel speed sensor

• 5.
  
  If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

• 6.
  
  
  NOTE: Make sure to use the latest scan tool software release.

  If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).

• 7.
  
  
  NOTE: The Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.

  If the scan tool does not communicate with the VCM :

  • check the VCM connection to the vehicle.
  • check the scan tool connection to the VCM.
  • refer to Module Communications Network , No Power To The Scan Tool, to diagnose no power to the scan tool.

• 8.
  
  If the scan tool does not communicate with the vehicle:
  • verify the ignition is ON.
    • the air bag indicator (other indicators may not prove ignition ON. If the ignition does not turn on, refer to Steering Column Switches to diagnose no power in RUN.
  • verify the scan tool operation with a known good vehicle.
  • refer to Module Communications Network to diagnose no response from the PCM.

• 9.
  
  Carry out the network test.
  • If the scan tool responds with no communication for one or more modules, refer to Module Communications Network .
  • If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).

• 10.
  
  Clear the CMDTCs and carry out the self-test diagnostics for the ABS module, the SCCM and the IPC.

• 11.
  
  If the DTCs retrieved are related to the concern, go to the ABS Module DTC Chart , or the IPC DTC Chart. For all other DTCs, refer to Multifunction Electronic Modules .

• 12.
  
  If no DTCs related to the concern are retrieved, GO to Symptom Chart .