Circuit Description
As the wheel spins, the wheel speed sensor produces an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.
Conditions for Running the DTC
Ignition switch in the RUN position.
Conditions for Setting the DTC
The corresponding sensor output voltage is detected as being high (above 3.33 volts) for greater than 0.1 seconds, or low (below 0.039 volts) for greater than 0.5 seconds.
Action Taken When the DTC Sets
| • | The ABS indicator lamp turns on. |
| • | The ABS disables 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. |
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 lamp is on only during humid conditions such as rain, snow, or vehicle wash, thoroughly inspect all wheel speed sensor circuits 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 above 24 km/h (15 mph) for at least 30 seconds.
If the DTC returns, replace the suspected harness.
When inspecting a wheel speed sensor, inspect the sensor terminals and the harness connector for corrosion. If evidence of corrosion exists, replace the wheel speed sensor. 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? | 1575-3800 ohms | Go to Step 4 | Go to Step 8 |
4 |
Does the AC voltage measure greater than the specified value? | 50 mV | Go to Step 5 | Go to Step 8 |
5 | 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 10 | Go to Step 6 |
6 | Test the wheel speed sensor circuits for the following:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 |
7 | 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 10 | Go to Step 9 |
8 | Replace the wheel speed sensor. Refer to Wheel Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
9 |
Important: Perform the tire size calibration in Scan Tool Diagnostics. Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
