Diagnostic Test

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

VERIFY DTC IS ACTIVE
NOTE:
Inspect the tires for improper air pressure and or mismatched tires before continuing, repair as necessary.
1. Turn the ignition on.
2. With the scan tool, record and erase DTCs.
  CAUTION:
  Make sure brake capability is available before road testing.
3. Road test the vehicle over 40 km/h (25 mph).
4. With the scan tool, read DTCs.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
CHECK WHEEL SPEED SENSOR SIGNALS
1. Turn the ignition on.
2. With the scan tool, monitor and graph ALL the Wheel Speed Sensors speeds and compare.
3. Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph).
  Is one or more of the WSS speeds showing 0 km/h (0 mph) or not matching the other WSS speeds?
  
  Yes
  - Go To 3
  No
  - Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
INSPECT WHEEL SPEED SENSOR FOR DAMAGE
NOTE:
Check all terminals for broken, bent, pushed out, or corroded terminals.
1. Turn the ignition off.
2. Inspect each WSS for looseness and or not properly fastened.
  Are any WSS loose or any of the wiring/connectors/terminals damaged?
  
  Yes
  - Repair as necessary.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 4
CHECK EACH HUB AND WHEEL BEARING FOR DAMAGE
1. Turn the ignition off.
2. Inspect each Hub and Wheel Bearing for damage, corrosion, cracks, looseness, or improper installation.
  Are any of the Hub and or Wheel Bearings damaged?
  
  Yes
  - Replace the Hub and Wheel Bearing in accordance with the Service Information. For front suspension, refer to. For rear suspension, refer to HUB AND BEARING, REMOVAL
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 5
ANTI-LOCK BRAKE SYSTEM (ABS) MODULE
1. Replace the Wheel Speed Sensor in accordance with the Service Information. Refer to SENSOR, WHEEL SPEED, FRONT, REMOVAL .
2. Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
3. With the scan tool, monitor and graph ALL the Wheel Speed Sensors speeds and compare.
4. Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph).
5. With the scan tool, read the DTCs.
  Does this 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, REMOVAL .
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Test complete.