GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Impala 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1248

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 the existing ABS in order to regulate the vehicle's rear brake pressure.

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 exits:

    • DTC C1236 sets and ignition voltage is less than 8.5 volts.
    • DTC C1254 or C1255 sets.
    • DTCs C1265 and C1267 set.
    • 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
    • Use this DTC in order to differentiate which of the following conditions is present:
       - The EBCM turned ON the red Brake warning indicator.
       - The instrument cluster turned ON the red Brake warning indicator due to low brake fluid in the master cylinder reservoir.
       - The body control module turned ON the red Brake warning indicator due to the application of the park brake.
    • Diagnose any other ABS DTCs that set along with this DTC.

Test Description

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

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

Step

Action

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 - ABS

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 EBCM.

Does the scan tool display any ABS/TCS DTCs?

Go to Diagnostic Trouble Code (DTC) List

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 in Wiring System