Circuit Description
The EBCM supplies 5 volts through an internal resistance and then to the wheel speed sensor. If a wheel speed sensor/circuit is open, the voltage drop across the internal resistance is low and the feedback voltage is high. A shorted sensor/circuit causes the feedback voltage to be low.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The left front wheel speed sensor feedback voltage is detected as being high (greater than 3.33 volts) for 100 milliseconds or low (less than 0.039 volts) for 500 milliseconds.
Action Taken When the DTC Sets
| • | The ABS indicator is commanded ON. |
| • | The ABS is disabled for as long as the malfunction is present. |
Conditions for Clearing the DTC
| • | Repair the conditions responsible for setting the DTC. |
| • | Use a scan tool in order to clear the DTC. |
| • | After the DTC is cleared and the ignition is ON, the ABS indicator remains on until the EBCM completes a power-up self-test. This test concludes when the vehicle reaches a speed of greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM. |
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Inspect for the following:
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Corrosion |
| • | Improperly formed or damaged terminals |
| • | Poor terminal-to-wiring connections |
| • | Physically damaged wiring |
| • | Wiring broken inside the insulation |
If the customer's concern is that the ABS indicator is on only during humid conditions such as rain, snow or vehicle wash, thoroughly inspect the wheel speed sensor circuit(s) for signs of water intrusion. Use the following procedure to help isolate the problem area:
- Spray the suspected area with a 5% salt water solution (two teaspoons of salt to 12 oz. of water).
- Drive the vehicle at a speed greater than 24 km/h (15 mph) for at least 30 seconds.
Replace the suspect harness if the DTC sets.
Inspect the terminal cavity of the wheel speed sensor for corrosion. Replace the wheel speed sensor if corrosion exists. Refer to Wheel Speed Sensor Replacement
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | ||||||||||||
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check | ||||||||
2 |
Does the DTC set? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||||
3 |
Does the resistance measure within the specified range? | 700-2000 ohms | Go to Step 4 | Go to Step 7 | ||||||||
4 | Inspect for poor connections at the harness connector of the wheel speed sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 | ||||||||
5 | Test the wheel speed sensor circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | ||||||||
6 | Inspect for poor connections at the harness connector for the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||||
7 | Replace the wheel speed sensor. Refer to Wheel Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
8 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Important: Perform the Tire Size Calibration procedure. Refer to Scan Tool Diagnostics Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
9 |
Does the DTC set? | -- | Go to Step 3 | System OK | ||||||||
