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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0229 Drop Out of Both Front Speed Sensors
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The vehicle speed is greater than 32 km/h (20 mph) when the brake is applied or 19 km/h (12 mph) when the brake is released. |
Conditions for Setting the DTC
The EBCM detects an erratic signal from both front wheel speed sensors for 105 milliseconds.
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the ABS/TCS/DRP. |
| • | The ABS indicator turns ON. |
| • | The TRACTION OFF indicator turns ON. |
| • | The red brake warning indicator turns ON. |
Conditions for Clearing the DTC
| • | Repair the condition 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 may remain ON until the EBCM completes a power-up self-test. This test concludes when the vehicle reaches a speed greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM. |
Diagnostic Aids
Operating the vehicle on extremely rough terrain can set DTC C0223, C0227 or C0229 even if the system is functioning normally.
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
If the customer 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 circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:
- Spray the suspected area with a 5 percent salt water solution.
- Drive the vehicle at a speed greater than 19 km/h (12 mph) for at least 30 seconds.
Repair or replace the suspect harness if the DTC sets.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the DTC set? | Go to Step 3 | Go to Diagnostic Aids |
3 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 | Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 5 | -- |
5 |
Does the DTC reset? | Go to Step 3 | System OK |
