For 1990-2009 cars

### Circuit Description

The dynamic rear proportioning (DRP) is a control system that replaces the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The DRP control system is part of the operating software in the EBCM. The DRP uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0281 DRP performance

### Conditions for Running the DTC

One or more faults have been detected by the EBCM in the ABS/TCS systems.

### Conditions for Setting the DTC

One of the following conditions occurs:

• | DTC C0121, C0113, C0114, C0115, C0900, or C0550 sets.

• | Two wheel speed sensor DTCs on the same axle set.

### Action Taken When the DTC Sets

• | The EBCM disables the DRP for the duration of the ignition cycle.

• | The Red Brake Warning Indicator turns ON.

### Conditions for Clearing the DTC

• | The condition for the DTC is no longer present and the DTC is cleared with a scan tool.

• | The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

### Diagnostic Aids

This DTC is for information only. As an aid to the technician, this DTC indicates that another DTC exists that fails DRP.

### Test Description

The number below refers to the step number on the diagnostic table.

1. Verifies whether other ABS/TCS/VSES DTCs are set.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Antilock Brake System Schematics
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Select the display DTCs function on the scan tool for the electronic brake control module (EBCM).

Does the scan tool display any ABS/TCS/VSES DTCs?

Go to Diagnostic System Check - Vehicle

Go to Step 3

3 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

Go to Testing for Intermittent Conditions and Poor Connections