Circuit Description
The toothed wheel generates a voltage pulse as it moves past the sensor. Each tooth-gap-tooth series on the wheel generates the pulses. The electronic brake control module (EBCM) uses the frequency of these pulses to determine the wheel speed. The voltage generated depends on the air gap between the sensor and the toothed wheel, and on the wheel speed.
This procedure inspects for a malfunctioning wheel speed sensor, a short to ground or to voltage in the wiring, or a contact problem in a connector.
Conditions for Setting the DTC
| • | The wheel speed sensor is defective or disconnected. |
| • | There is a problem in the wiring. |
| • | There is a problem with a connector. |
| • | There is a problem in the toothed ring. |
| • | Wrong installed wheel speed sensor (WSS) |
| • | Wrong sensor signal |
| • | Signal noise via WSS |
Action Taken When the DTC Sets
The antilock brake system (ABS) action is disabled, and the ABS warning lamp is ON. The electronic brake force distribution (EBD) is enabled. Refer to the EBD failure matrix in ABS Description and Operation .
Diagnostic Aids
Be sure that the speed sensor wiring is properly routed and retained. This will help to prevent false signals due to the pickup of electrical noise.
It is very important to perform a thorough inspection of the wiring and the connectors. Failure to inspect the wiring and the connectors carefully and completely may result in misdiagnosis, causing part replacement with the reappearance of the malfunction.
Important: If the WSS signal fault input to the electronic brake control module (EBCM), the ABS warning lamp turns ON. If a sensor signal fault can be removed by the scan tool, the ABS warning lamp doesn't turn OFF. In order to turn ABS warning lamp OFF, you should drive the vehicle up to 12 km/h.
You can use the scan tool to monitor wheel speeds during a road test. Watch the wheel speeds being displayed on the scan tool to see if any of the readings are unusual, such as 1 sensor varying in speed from the other 3, a signal going intermittently high or low, etc. If this does not identify the intermittent, wet the speed sensor harness on the underside of the vehicle and perform a road test, monitoring the wheel speeds with the scan tool.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step begins an examination for a defective wheel speed sensor.
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This step tests the wiring for a short to voltage.
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This step tests the wiring for a short to ground.
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This step tests for an open or high resistance in the wiring.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Inspect the wheel speed sensor. Are there any signs of physical damage? | -- | Go to Step 3 | Go to Step 2 | |
2 |
Is the resistance within the specified range at approximately 25°C (77°F)? | 1280-1920 ohms | Go to Step 4 | Go to Step 3 |
3 | Replace the wheel speed sensor. Did you complete the replacement? | -- | System OK | -- |
4 |
Is the output equal to the specified value? | 120 V | Go to Step 6 | Go to Step 5 |
5 | Replace the speed sensor or the toothed wheel as required. Did you complete the replacement? | -- | System OK | -- |
Is the voltage for either of the terminals less than the specified value? | 1 V | Go to Step 7 | Go to Step 8 | |
7 | Repair the short to voltage in the affected circuit. Did you complete the repair? | -- | System OK | -- |
Is the resistance at either circuit less than the specified value? | ∞ | Go to Step 9 | Go to Step 10 | |
9 | Repair the short to ground in the affected circuit. Did you complete the repair? | -- | System OK | -- |
Is the resistance on either circuit less than the specified value? | 5 ohms | Go to Step 11 | Go to Step 12 | |
11 | Repair the open or high resistance in the affected circuit as required. Inspect terminals 3 and 10 of connector C110 and terminals 1 and 2 of connector C901. Did you complete the repair? | -- | System OK | -- |
12 | Replace the ABS unit. Did you complete the replacement? | -- | System OK | -- |
