Circuit Description
The EBCM receives the rear wheel speed signal from the PCM (6.5L only) or the VCM. The signal from the VCM/PCM is always high (12 Volts) when the ignition is on and the vehicle is not moving. When the vehicle is moving, the VCM/PCM toggles this voltage on and off. The EBCM uses the frequency of this signal to calculate the rear wheel speed.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The front wheel speed sensor signals are both greater than 13 km/h (8 mph). |
Conditions for Setting the DTC
The rear wheel speed sensor signal is less than 6 km/h (4 mph) for 5 seconds.
Action Taken When the DTC Sets
| • | The ABS and BRAKE indicators are commanded on. |
| • | The ABS and DRP are 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 |
Test Description
The number below refers to the step number on the diagnostic table.
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 |
Does the voltage measure within the specified value? | 5-7 volts | Go to Step 5 | Go to Step 4 | |
4 | Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | 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 9 | Go to Step 6 |
6 | 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 | -- |
7 | Inspect for poor connections at the harness connector of the VCM/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 9 | Go to Step 8 |
8 |
Important: Perform the setup procedure for the VCM/PCM. Replace the VCM/PCM. Refer to VCM Replacement/Programming in Engine Controls - 5.0L and 5.7L, Powertrain Control Module Replacement/Programming in Engine Controls - 6.5L (L65) or VCM Replacement/Programming in Engine Controls - 7.4L. Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC set? | -- | Go to Step 3 | System OK |
