C1027-LEFT REAR WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.
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When Monitored:
With the ignition on.
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Set Condition:
When the Left Rear 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.
Possible Causes |
|---|
| LEFT REAR WSS LOOSE - B3, B4 CIRCUITS/CONNECTOR/TERMINAL DAMAGE |
| LEFT REAR TONE WHEEL DAMAGE |
| LEFT REAR WHEEL BEARING DAMAGE |
| AXLE SHAFT FASTENER HARDWARE |
| IMPROPER LEFT REAR TIRE PRESSURE/MISMATCHED TIRES |
| LEFT REAR WSS |
| ANTI-LOCK BRAKE MODULE |
1. CHECK FOR DTC C1027-LEFT REAR WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE
| NOTE: | This DTC must be active for the results of this test to be valid. |
| 1. | Turn the ignition on. |
| 2. | With the scan tool, record and erase DTCs. |
Make sure braking capability is
available before road testing.
CAUTION:
| 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 met. |
| 4. | With the scan tool, read DTCs. |
Does the scan tool display: C1027-LEFT REAR WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE active?
Yes
- Go To 3
No
- Go To 2
2. CHECK WHEEL SPEED SENSOR SIGNALS
| 1. | Turn the ignition on. |
| 2. | 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. |
| 3. | Slowly accelerate as straight as possible from a stop to 40 km/h (25 mph). |
Is the Left Rear WSS speed showing 0 km/h (0 mph) or not matching other wheels or showing erratic behavior?
Yes
- Go To 3
No
- Perform ABS INTERMITTENT CONDITION diagnostic procedure, (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
3. CHECK FOR IMPROPER LEFT REAR TIRE PRESSURE/MISMATCHED TIRES
| 1. | Turn the ignition off. |
| 2. | Check and adjust the Left Rear Tire pressure. |
| 3. | Check and adjust all other tire pressures. |
| 4. | Inspect for mismatched tires on vehicle. |
Is the Left Rear Tire improperly inflated or mismatched tires on vehicle?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No
- Go To 4
4. CHECK AXLE SHAFT FASTENER HARDWARE FOR LOOSENESS
| 1. | Inspect the axle shaft fastener for looseness, and not properly fastened. Tighten fastener to proper specification as required. |
Was the Axle Shaft fastener loose?
Yes
No
- Go To 5
5. CHECK LEFT REAR WSS LOOSENESS, INSPECT B3, B4 CIRCUITS/TERMINALS FOR DAMAGE
| NOTE: | Check all terminals for broken, bent, pushed out, or corroded terminals |
| 1. | Inspect the Anti-Lock Brake Module harness connector, Left Rear WSS, and Left Rear WSS harness connector |
| 2. | Inspect the Left Rear WSS for looseness, excessive corrosion and not properly fastened. |
| 3. | Inspect the (B3) Left Rear WSS Signal and (B4) Left Rear WSS Supply circuits between the Left Rear WSS and Anti-Lock Brake Module for damage. |
Is the Left Rear WSS loose or any of the wiring/connectors/terminals damaged?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No
- Go To 6
6. CHECK LEFT REAR WHEEL SPEED SENSOR FOR DAMAGE
| 1. | Remove the Left Rear Wheel Speed Sensor |
| 2. | Inspect the Left Rear Wheel Speed Sensor face for damage. |
Is the Left Rear Wheel Speed Sensor damaged?
Yes
- Replace sensor and hub assembly.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No
- Go To 7
7. CHECK LEFT REAR TONE WHEEL FOR DAMAGE
| 1. | Inspect the Left Rear Tone Wheel for damage, missing teeth, cracks, corrosion or looseness. |
| NOTE: | The Tone Wheel teeth should be perfectly square, not bent, or nicked. |
Is the Left Rear Tone Wheel damaged?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No
- Go To 8
8. CHECK LEFT REAR WHEEL BEARING FOR DAMAGE
| 1. | Inspect the Left Rear wheel bearing for excessive runout or clearance. |
| NOTE: | Refer to the appropriate service information, if necessary, for procedures or specifications. |
Is the Left Rear Wheel Bearing Damaged?
Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No
- Go To 9
9. LEFT REAR WHEEL SPEED SENSOR
| 1. | Replace the Left Rear Wheel Speed Sensor in accordance with the Service Information. |
| 2. | Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure). |
| 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 met. |
| 4. | With the scan tool, read ABS DTCs. |
Did DTC C1027-LEFT REAR WHEEL SPEED SENSOR SIGNAL ERRATIC PERFORMANCE reset?
Yes
- Replace the Anti-Lock Brakes Module in accordance with the Service Information.
- Perform ABS VERIFICATION TEST (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).
No