C123C

DTC C123C, C1255, or C1256

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC C123C 00

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Electronic Brake Control Module RAM Malfunction

DTC C1255 00

-
Electronic Control Unit Performance Malfunction

DTC C1256 00

-
Control Module Programming Checksum Error Malfunction

Circuit/System Description

When the ignition is turned ON, the microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. If an internal malfunction is detected, the control module will set a DTC.

Conditions for Running the DTC

Ignition ON

Conditions for Setting the DTC

The control module detects an internal malfunction.

Action Taken When the DTC Sets

Specific subsystems will not function or operate in degraded mode.

Conditions for Clearing the DTC

* The current DTC clears when the diagnostic runs and passes.

* The history DTC will clear after 40 consecutive fault-free drive cycles have occurred.

Reference Information

Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems

Connector End View Reference

Component Connector End Views Sunshade - Left (DH6)

Description and Operation

ABS Description and Operation Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC C0569, C056D, or C056E is not set.

• If any of the DTCs are set

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

• If none of the DTCs are set

3. Replace the K17 electronic brake control module.

4. Verify that DTC C123C, C1255, or C1256 does not set while operating the vehicle under the Conditions for Running the DTC.

• If any of the DTCs are set

Replace the control module that set the DTC.

• If none of the DTCs are set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

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