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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Accessories 🢒 Navigation Systems 🢒 DTC C0291

Circuit Description

The park brake system uses a pair of solenoids to set or release the park brake pedal. These solenoids are powered by relays which are commanded ON and OFF by the body control module (BCM). When the gear shift lever is taken out of Park or Neutral, the BCM simultaneously activates both solenoids to release the park brake pedal. Solenoid A is deactivated after 2 seconds and solenoid B remains activated until the gear shift lever is in Park or Neutral, the engine is OFF, and the park brake switch is closed.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0291 Park Brake Release Relay Circuit

DTC Symptom

DTC Symptom Descriptor

02

Short to Ground

05

Short to Battery or Open

Conditions for Running the DTC
    • The ignition is ON.
    • Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC

C0291 02

The BCM detects park brake relay A circuit is shorted to ground.

C0291 05

The BCM detects one of the following conditions:

    • The park brake relay A circuit is shorted to battery.
    • The park brake relay A circuit is open.

Action Taken When the DTC Sets

The ABS 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

DTC C0291 02

The park brake relay A circuit is shorted to ground.

DTC C0291 05

Possible causes of this DTC are the following conditions:

    • The park brake relay A circuit is shorted to voltage.
    • The park brake relay A circuit is open.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the park brake release relay control circuit for power.

    2.

  2. This step tests for an open in the park brake release relay ground circuit.

    3.

  3. This step tests for an open, a short to ground, or a short to B+ in the park brake release relay control circuit.

Step

Action

Yes

No

Schematic Reference: Park Brake System Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Remove the park brake release relay from the relay block.
  2. Connect the test light between the ground and C2 on the relay block.
  3. With a scan tool, command relay A ON.

Did the test light come ON?

Go to Step 3

Go to Step 4

3

Check for an open in relay A ground circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and repair the condition?

Go to Step 7

Go to Step 5

4

Check for an open, a short to ground, or a short to B+ in the park brake relay coil 1 control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 7

Go to Step 6

5

Replace the park brake release relay.

Did you complete the replacement?

Go to Step 7

--

6

Replace the body control module (BCM). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7

Clear the DTCs, then operate the park brake.

Does the park brake release?

System OK

Go to Step 2