C1027

C1027-LEFT REAR WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

NOTE: The Electronic Stability Control (ESC) may also be referred to as Electronic Stability Program (ESP) depending on the vehicle model year and configuration. Certain components may also reference ESP, ESC, or use the traction control symbol.

- When Monitored:
With the ignition on.

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





1. DTC IS ACTIVE
1. Ignition on, engine not running.
2. With the scan tool, erase DTCs.
3. Turn the ignition off to the lock position.
4. Ignition on, engine not running.
5. With the scan tool, read DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

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

2. WHEEL SPEED SENSOR INSPECTION
1. Turn the ignition off to the lock position.
2. Inspect the Wheel Speed Sensor for proper mounting.
3. Inspect the Wheel Speed Sensor harness and connector.
4. Inspect the Wheel Speed Sensor for excessive debris on the sensor.

Were any problems found?

Yes

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

No

- Go To 3

3. TONE WHEEL DAMAGED/MISSING
1. Inspect the Tone Wheel.

NOTE: The Tone Wheel Teeth should be perfectly square, not bent or nicked.

Were any problems found?

Yes

- Replace the Tone Wheel.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 4

4. EXCESSIVE WHEEL SPEED SENSOR AIR GAP
1. Measure the Wheel Speed Sensor Air Gap.

Were any problems found?

Yes

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

No

- Go To 5

5. WHEEL BEARING LOOSE/BINDING
1. Inspect the wheel bearings for excessive run out or improper clearance.

Were any problems found?

Yes

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

No

- Go To 6

6. CHECK (B4) LEFT REAR WHEEL SPEED SENSOR SUPPLY CIRCUIT VOLTAGE




1. Disconnect the Left Rear Wheel Speed Sensor harness connector.
2. Turn the ignition on.
3. Measure the voltage between the (B4) Left Rear Wheel Speed Sensor Supply circuit and ground.

Is the voltage above 10 volts?

Yes

- Go To 7

No

- Go To 9

7. (B4) LEFT REAR WHEEL SPEED SENSOR SUPPLY CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off to the lock position.
2. Disconnect the ABS Module harness connector.
3. Ignition on, engine not running.
4. Measure the voltage of the (B4) Left Rear Wheel Speed Sensor Supply circuit.

Is there any voltage present?

Yes

- Repair (B4) Left Rear Wheel Speed Sensor Supply circuit for a short to voltage.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 8

8. (B3) LEFT REAR WHEEL SPEED SENSOR SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Measure the resistance between the (B3) Left Rear Wheel Speed Sensor Signal circuit and ground.

Is the resistance above 5.0 Ohms?

Yes

- Replace the Left Rear Wheel Speed Sensor.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Repair the (B3) Left Rear Wheel Speed Sensor Signal circuit for a short to ground.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

9. (B4) LEFT REAR WHEEL SPEED SENSOR SUPPLY CIRCUIT SHORTED TO GROUND




1. Turn the ignition off to the lock position.
2. Disconnect the ABS Module harness connector.
3. Measure the resistance between the (B4) Left Rear Wheel Speed Sensor Supply circuit and ground.

Is the resistance above 5.0 Ohms?

Yes

- Go To 10

No

- Repair the (B4) Left Rear Wheel Speed Sensor Supply circuit for a short to ground.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

10. (B4) LEFT REAR WHEEL SPEED SENSOR SUPPLY CIRCUIT OPEN




1. Measure the resistance of the (B4) Left Rear Wheel Speed Sensor Supply circuit between the ABS harness connector and the Left Rear Wheel Speed Sensor harness connector.

Is the resistance below 5 Ohms?

Yes

- Go To 11

No

- Repair the open (B4) Left Rear Wheel Speed Sensor Supply circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

11. (B3) LEFT REAR WHEEL SPEED SENSOR SIGNAL CIRCUIT OPEN




1. Measure the resistance of the (B3) Left Rear Wheel Speed Sensor Signal circuit between the ABS harness connector and the Left Rear Wheel Speed Sensor harness connector.

Is the resistance below 5 Ohms?

Yes

- Go To 12

No

- Repair the open (B3) Left Rear Wheel Speed Sensor Signal circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

12. (B3) LEFT REAR WHEEL SPEED SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition on.
2. Measure the voltage of the (B3) Left Rear Wheel Speed Sensor Signal circuit at the Left Rear Wheel Speed Sensor harness connector.

Is there any voltage present?

Yes

- Repair the (B3) Left Rear Wheel Speed Sensor Signal circuit for a short to voltage.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 13

13. (B4) LEFT REAR WHEEL SPEED SENSOR SUPPLY CIRCUIT SHORTED TO THE (B3) LEFT REAR WHEEL SPEED SENSOR SIGNAL CIRCUIT




1. Turn the ignition off to the lock position.
2. Measure the resistance between the (B4) Left Rear Wheel Speed Sensor Supply circuit and the (B3) Left Rear Wheel Speed Sensor Signal circuit at the ABS Module harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair (B4) Left Rear Wheel Speed Sensor Supply circuit for a short to the (B3) Left Rear Wheel Speed Sensor Signal circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

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