Buick Regal: DTC C056E

Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

DTC Descriptor

DTC C056E 4B

Electronic Control Unit Software - Calibration Not Learned

Symptom Byte Information: Symptom Byte List

Circuit/System Description

For an overview of the component/system, refer to:Electronic Parking Brake Description

Conditions for Running the DTC

Ignition = On

Conditions for Setting the DTC

• K17 Electronic Brake Control Module = Missing Calibration - Electric Park Brake (J71)

Actions Taken When the DTC Sets

Electric Park Brake = DegradedorDisabled

Conditions for Clearing the DTC

K17 Electronic Brake Control Module = Calibrated - Electric Park Brake (J71)

Reference Information

Schematic Reference

Park Brake System Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEW INDEX

Master Electrical Component List

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification

DTC C056E 4B

1. Ignition - On / Vehicle - In Service Mode

2. Verify DTC C056E 4B is not set.

• If the DTC is set

1. Perform the necessary programming and setup procedure: K17 Electronic Brake Control Module - Step 4
2. Verify the DTC does not set.
   • If the DTC sets - Replace the component: K17 Electronic Brake Control Module
   • Go to next step: If the DTC is not set
3. All OK.

• Go to next step: If the DTC is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification

For control module replacement, programming, and setup refer to: Control Module References

DTC C1138

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC C1138 03

Supply Voltage Goes Below 7 V

DTC C1138 07

Supply Voltage Goes Above 16.5 V

DTC C1138 58

Signal Performance

Diagnostic Fault Information

Circuit/System Description

The Electronic Brake Control Module monitors its supply voltage to verify the supply voltage is within the normal operating range

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

DTC C1138 03

The EBCM detects its supply voltage of less than approximately 7 V.

DTC C1138 07

The EBCM detects a supply voltage of more than 16.5 V.

DTC C1138 58

The Park Brake Controller (PBC) loses communication with the EBCM during park brake actuation.

Action Taken When the DTC Sets

• DTC is stored in memory.
• Park brake actuation unavailable.

Conditions for Clearing the DTC

The supply voltage returns to normal operating range.

Diagnostic Aids

• A high or low voltage DTC set or voltage value in multiple modules/sensors indicates a concern in the charging system.
• A possible cause of this DTC could be overcharging with a battery charger or jump starting.

Reference Information

Schematic Reference

Park Brake System Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEW INDEX

Description and Operation

Electronic Parking Brake Description

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify that no other DTCs are set.

• If any other DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

• Go to next step: If no other DTCs are set

2. Vehicle OFF, measure and record the battery voltage at the battery terminals.

3. Verify the battery voltage stabilizes between 12.4 V and 12.8 V within a few minutes of turning the vehicle OFF.

• If battery voltage is less than 12.4 V or more than 12.8 V

Refer to Battery Inspection/Test.

• Go to next step: If battery voltage is between 12.4 and 12.8 V

4. Engine running, headlights ON, measure and record the battery voltage at the battery terminals.

5. Verify the voltage is at least 1 V greater than the voltage measured in step 1, but less than 15 V.

• If the voltage is not at least 1 V greater than the voltage measured in step 2 or is greater than 15 V.

Refer to Charging System Test.

• Go to next step: If the voltage is at least 1 V greater than the voltage measured in step 2, but less than 15 V

6. Verify the K17 Electronic Brake Control Module scan tool ignition voltage parameter is within 1 V of the battery voltage.

• If not within 1 V of the battery voltage

Refer to Circuit/System Testing.

• Go to next step: If within 1 V of the battery voltage

7. All OK.

Circuit/System Testing

NOTE:

• You must perform the Circuit/System Verification before Circuit/System Testing.
• Some control module ground circuits may require up to 20 min after the ignition is turned off before achieving a resistance reading of less than 5 Ω. In most cases the readings will drop below 20 Ω within 1 min indicating the control module is going to sleep.

DTC C1138 03 or DTC C1138 07

1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K17 Electronic Brake Control Module. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between ground circuit terminal 46 and ground.

• If 10 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 Ω

3. Verify a test lamp illuminates between B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF.
2. Test for less than 2 Ω in the B+ circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K17 Electronic Brake Control Module.

• Go to next step: If the test lamp illuminates

4. Replace the K17 Electronic Brake Control Module.

DTC C1138 58

1. Verify that no other DTCs are set.

• If any other DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

• Go to next step: If no other DTCs are set

2. Using the S91 Park Brake Control Switch, apply and release the park brake.

3. Verify that the DTC does not reset.

• If the DTC resets

Replace the K17 Electronic Brake Control Module.

• Go to next step: If the DTC does not reset

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for control module replacement, programming and setup.

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