The PCM detects low voltage on the vehicle speed signal circuit for 45 seconds.
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
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Electrical Intermittents , Testing for Intermittent Conditions and Poor Connections , Wiring Repairs and Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 3: This step tests for a voltage signal from the PCM.
- 4: This step tests for a missing or erratic vehicle speed signal from the PCM. An assistant may be required to perform this test.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: ABS Schematics Connector End View Reference: ABS Connector End Views , Powertrain Control Module (PCM) Connector End Views in Engine Controls - 4.8L, 5.3L and 6.0L or Powertrain Control Module (PCM) Connector End Views in Engine Controls - 8.1L | ||||
| 1 | Did you perform the ABS Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - ABS | |
| 2 | Use a scan tool in order to clear the DTCs. Operate the vehicle at a speed greater than the specified value. Does the DTC set? | 19 km/h (12 mph) | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Turn OFF the ignition. Disconnect from the EBCM, the harness connector containing the vehicle speed signal circuit. Turn ON the ignition. Use a DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground. Does the voltage measure greater than the specified value? | 10 V | Go to Step 4 | Go to Step 7 |
| 4 | Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Place the transmission in neutral (N). Set up the DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground. Spin the rear wheels as fast as possible by hand for at least 30 seconds and while ensuring the driveshaft is rotating, observe the DMM. Does the voltage measure within the specified range the entire time the driveshaft is rotating? | 5-7 V | Go to Step 5 | Go to Step 7 |
| 5 | Inspect for poor connections at the harness connector of 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 6 | |
| 6 | IMPORTANT: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Electronic Brake Control Module Replacement .Did you complete the replacement? | Go to Step 10 | ||
| 7 | Test the vehicle speed signal circuit for an open, a short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 10 | Go to Step 8 | |
| 8 | Inspect for poor connections at the harness connector of the PCM. 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 | |
| 9 | IMPORTANT: Perform the setup procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L, or Powertrain Control Module (PCM) Replacement in Engine Controls - 8.1L.Did you complete the replacement? | Go to Step 10 | ||
| 10 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 3 | System OK | |
| IMPORTANT |
|---|
| Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure. |
| IMPORTANT |
|---|
| Perform the setup procedure for the PCM. |
DTC C0235-C0237 or P0609
Circuit Description
As the front wheels spin, the wheel speed sensors (WSSs) produce an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed. The powertrain control module (PCM) converts the data from the vehicle speed sensor (VSS) to a 128k pulses/mile signal. The EBCM uses the vehicle speed signal from the PCM in order to calculate the rear wheel speed.
Conditions for Running the DTC
The ignition is ON and the vehicle speed is between 24 km/h (15 mph) and 80 km/h (50 mph).
Conditions for Setting the DTC
The EBCM detects that one wheel speed input is 10 percent greater than or 10 percent less than the other wheel speed inputs within 3.2 km (2 mi) of driving.
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.
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Installing one tire of significantly different size on the vehicle causes DTC C0238 to set. Operating the vehicle with a tire that has very low air pressure may also set this DTC. Inspect the vehicle for an incorrect or damaged wheel speed sensor or vehicle speed sensor if the tires and the EBCM and PCM calibrations are OK.
The number below refers to the step number on the diagnostic table.
- 4: If the front tires are not the same size as the rear tires, the EBCM calibration must match the FRONT tire size and the PCM calibration must match the REAR tire size.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the ABS Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - ABS |
| 2 | Inspect both of the front tires on the vehicle to ensure that both tires are of equal size. Are both of the front tires of equal size? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Inspect both of the rear tires on the vehicle to ensure that both tires are of equal size. Are both of the rear tires of equal size? | Go to Step 4 | Go to Diagnostic Aids |
| 4 | Verify the EBCM and the PCM both have the correct tire size calibration. Use the scan tool in order to view the EBCM tire size calibration or perform the Tire Size Calibration procedure and refer to Service Programming System (SPS) in Programming. Did you find and correct the condition? | Go to Step 5 | Go to Diagnostic Aids |
| 5 | Use a scan tool in order to clear the DTCs. Operate the vehicle for at least 3 minutes within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK |
DTC C0238
The ABS relay supplies battery voltage to 6 valve solenoids. The electronic brake control module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.
- The ignition is ON.
- The vehicle speed is greater than 6 km/h (4 mph).
The EBCM detects an internal malfunction.