C1011

C1011-LEFT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE

For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the ignition on.

- Set Condition:
When the Left Front Wheel Speed Sensor (WSS) Signal is intermittently missing while vehicle speed is above 40 km/h (25 mph) or erratic wheel speed signal during acceleration or sensed wheel speed is different from other wheels.





Diagnostic Test

1. CHECK FOR DTC C1011-LEFT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE
NOTE: This DTC must be active for the results of this test to be valid.

NOTE: If DTC C100A Left Front Wheel Speed Sensor Circuit is present it must be repaired before continuing.

Turn the ignition on.
With the scan tool, record and erase DTCs.

CAUTION: Ensure brake 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: C1011-LEFT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE active?

Yes

- Go to 3


No

- Go to 2

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

- Refer to the ABS-INTERMITTENT CONDITION TEST. ABS Intermittent Condition Test

3. 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. ABS Verification Test

No

- Go to 4

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. ABS Verification Test

No

- Go to 5

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. ABS Verification Test

No

- Go to 6

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. ABS Verification Test

No

- Go to 7

7. CHECK LEFT FRONT WHEEL BEARING FOR DAMAGE
Inspect the Left Front wheel bearing for excessive runout or clearance.

NOTE: Refer to the appropriate service information, if necessary, for procedures or specifications.

Is the Left Front Wheel Bearing Damaged?

Yes

- Repair as necessary.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Go to 8

8. LEFT FRONT WHEEL SPEED SENSOR
Replace the Left Front Wheel Speed Sensor.
Perform ABS VERIFICATION TEST. ABS Verification Test
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 C1011-LEFT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE reset?

Yes

- Replace the Anti-Lock Brakes Module.
- Perform ABS VERIFICATION TEST. ABS Verification Test

No

- Test Complete.