Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- CHECK FOR DTC C1014-LEFT FRONT WHEEL SPEED COMPARATIVE PERFORMANCE NOTE:
This DTC must be active for the results of this test to be valid.
- Turn the ignition on.
- With the scan tool, record and erase DTCs.CAUTION:
Make sure braking capability is available before road testing.
- 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 met.
- With the scan tool, read DTCs.
Does the scan tool display: C1014-LEFT FRONT WHEEL SPEED COMPARATIVE PERFORMANCE active?
Yes
- Go To 3
No
- Go To 2
- CHECK WHEEL SPEED SENSOR SIGNALS
- Turn the ignition on.
- With the scan tool, monitor and graph ALL the WSS speeds and compare graph while an assistant drives the vehicle.NOTE:
If graph shows periodic dropouts pay close attention to the tone wheel.
- Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph).
Is the Left Front WSS speed showing 0 km/h (0 mph) or not matching other wheels or showing erratic behavior?
Yes
- Go To 3
No
- The condition that caused the symptom is currently not present. Inspect the related wiring for a possible intermittent condition. Look for any chafed, pierced, pinched, or partially broken wires.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
- CHECK FOR IMPROPER LEFT FRONT TIRE PRESSURE/MISMATCHED TIRES
- Turn the ignition off.
- Check and adjust the Left Front Tire pressure.
- Check and adjust all other tire pressures.
- Inspect for mismatched tires on vehicle.
Is the Left Front Tire improperly inflated or mismatched tires on vehicle?
Yes
- Repair as necessary
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 4
- CHECK LEFT FRONT WSS LOOSENESS, INSPECT B8, B9 CIRCUITS/TERMINALS FOR DAMAGE NOTE:
Check all terminals for broken, bent, pushed out, or corroded terminals
- Inspect the Anti-Lock Brake Module harness connector, Left Front WSS, and Left Front WSS harness connector.
- Inspect the Left Front WSS for looseness, excessive corrosion and not properly fastened.
- Inspect the (B8) Left Front WSS Signal and (B9) Left Front WSS Supply circuits between the Left Front WSS and Anti-Lock Brake Module for damage.
Is the Left Front WSS loose or any of the wiring/connectors/terminals damaged?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 5
- CHECK LEFT FRONT WHEEL SPEED SENSOR FOR DAMAGE
- Remove the Left Front Wheel Speed Sensor
- Inspect the Left Front Wheel Speed Sensor face for damage.
Is the Left Front Wheel Speed Sensor damaged?
Yes
- Replace sensor and hub assembly.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 6
- CHECK LEFT FRONT TONE WHEEL/BEARING FOR DAMAGE
- Inspect the Left Front Tone Wheel/Bearing for damage, missing teeth, cracks, corrosion or looseness.NOTE:
The Tone Wheel teeth should be perfectly square, not bent, or nicked.
Is the Left Front Tone Wheel/Bearing damaged?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 7
- Inspect the Left Front Tone Wheel/Bearing for damage, missing teeth, cracks, corrosion or looseness.
- LEFT FRONT WHEEL SPEED SENSOR
- Replace the Left Front Wheel Speed Sensor in accordance with the Service Information.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
- 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 met.
- With the scan tool, read ABS DTCs.
Did DTC C1014-LEFT FRONT WHEEL SPEED COMPARATIVE PERFORMANCE reset?
Yes
- Replace the Anti-Lock Brakes Module in accordance with the Service Information.
- Perform ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Test Complete.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.