Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, read ABS DTCs and record on the repair order.
3. With the scan tool, read and record Freeze Fame information.
4. With the scan tool, erase DTCs.
5. Start the engine.
6. Test drive the vehicle above 40 km/h (25 mph).
7. With the scan tool, read ABS DTCs.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - Perform the ABS INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
COMPARE WHEEL SPEED SENSOR SIGNALS
WARNING:
Make sure brake capability is available before road testing.
1. With the scan tool, monitor ALL the WSS speeds while an assistant drives the vehicle.
2. Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph).
  Does the Left Rear WSS speed differ from the other WSS speeds by 8 km/h (5 mph) or show NO speed?
  
  Yes
  - Go To 4
  No
  - Go To 3
CHECKING INSIDE WHEEL SPEED
1. Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph) and perform a 90 degree turn while monitoring if inside wheel is slower than outside.
  Was the inside wheel slower than outside?
  
  Yes
  - Perform the ABS INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
  No
  - Go To 4
INSPECT TONE WHEEL/BEARING
1. Turn the ignition off.
2. Visually inspect the tone wheel and bearing for damage.
3. Check the tone wheel teeth for missing teeth, cracks, and looseness. The teeth must be perfectly square, not bent, or nicked. Check the wheel bearing for worn/looseness.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 5
CHECK WHEEL SPEED SENSOR (WSS) WIRING
1. Check the ABS Module and WSS harness connectors for incorrectly wired connectors.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 6
LEFT REAR WHEEL SPEED SENSOR (WSS)
1. Replace the Left Rear Wheel Speed Sensor (WSS) in accordance with the Service Information. Refer to SENSOR, WHEEL SPEED, REAR, REMOVAL .
2. Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  CAUTION:
  Make sure brake capability is available before road testing.
3. Road test the vehicle over 40 km/h (25 mph).
  NOTE:
  Vehicle must be driven above 40 km/h (25 mph) for set conditions to be meet.
4. With the scan tool, read ABS DTCs.
  NOTE:
  The Anti-lock Brake System (ABS) Module must sense ALL 4 wheels at 12 km/h (7.5 mph) before it will extinguish the ABS indicators.
  
  Does the DTC remain active?
  
  Yes
  - Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. Refer to MODULE, ANTI-LOCK BRAKE SYSTEM (ABS), REMOVAL .
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Test complete.