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Antilock Brake System (ABS) Antilock braking system is an enhanced braking system that monitors individual wheel rotation and prevents the wheels from locking up while stopping. Locked wheels provide inefficient braking and sacrifice directional control, so ABS shortens stopping distances in most conditions and allows the driver to steer even when panic braking. The federal government began requiring ABS on all new cars starting with the 2012 model year. Pulsation in the brake pedal can startle the uninitiated, but it is a sign of the ABS properly doing its job. In structure, ABS is similar to a conventional braking system, but its components may need repair, starting with electronic wheel sensors at each wheel or at the differential, the computer brain called the control module, and a valve assembly and pump. READ MORE: ANTI-LOCK BRAKING SYSTEM (ABS): COMPONENTS, TYPES AND WORKING PRINCIPLE Diagnostic Trouble Codes (DTC) When the ABS warning light in the Instrument Panel remains ON, the EHCU (Electronic Hydraulic Control Unit) stores the DTC and disables the ABS. DTC display: When the DTC display activated the ABS warning light will blink. The code is a Double-digit display. By counting the number of times the ABS warning light flashes, the DTC code can be determine. See the table below for the DTC Descriptions. The first code displayed is the normal DTC 12 and signifies the start and stop of a DTC flash sequence. It is displayed three times. If any other DTCs are stored in the EHCU they will be displayed three times. If no other DTCs have been stored then the display of DTC 12 will be repeated 3 times. The sequence repeats for 5 minutes or until the ignition switch is switch OFF or the jumper is removed. Starting the DTC Display The vehicle must be stopped and the brake pedal is not pressed in. The ignition switch must be in the off position. Install a jumper fromthe DLC terminal 12 to terminal 4 (see the diagram below). Turn on the Ignition Switch. Erasing the Codes During the first 3 seconds after the ignition switch is switched to the ON position, press the brake pedal 6 times. Actuation of the brake pedal switch during the EHCU self-diagnosis startup period clears the memory of the EHCU. Additionally, the EHCU memory will be cleared upon driving the vehicle above 8 mph and no faults detected by the EHCU. Diagnostic Trouble Codes (DTC) Code Flash outDiagnosisDescription12--13C02852 WD Controller in 4WD Vehicle Controller14C0271RAM read/write error14C0272ROM checksum error14C0270ALU function error14C0273Inoperative isolation item14C0284Loop time overrun15C0277Low ignition voltage15C0278High ignition voltage17C0269Excessive dump time18C0274Excessive isolation time21C0276G-Sensor Failure22C0281Brake switch Failure24C0282Open or shorted 4x4 input signal (4WD only)32C0267Open motor circuit or shorted ECU output32C0268Stalled motor or open ECU output35C0265Open relay circuit35C0266Shorted relay circuit41C0245FL Open isolation solenoid or shorted ECU output41C0247FL Shorted isolation solenoid or open ECU output42C0246FL Open dump solenoid or shorted ECU output42C0248FL Shorted dump solenoid or open ECU output43C0241FR Open isolation solenoid or shorted ECU output43C0243FR Shorted isolation solenoid or open ECU output44C0242FR Open dump solenoid or shorted ECU output44C0244FR Shorted dump solenoid or open ECU output45C0251 f^ •Rear Open isolation solenoid or shorted ECU output45C0253Rear Shorted isolation solenoid or open ECU output46C0252Rear Open dump solenoid or shorted ECU output46C0254Rear Shorted dump solenoid or open ECU output51C0225FL Open or shorted sensor52C0221FR Open or shorted sensor53C0235Rear Open or shorted sensor61C0226FL Missing sensor signal61C0227FL Sensor signal dropout62C0222FR Missing sensor signal62C0223FR Sensor signal dropout63C0236Rear Missing sensor signal63C0237Rear Sensor signal dropout64C0229Simultaneous dropout of front sensor signal65C0238Wheel speed error - Additional - This file contains information transposed from the BMW Car Club of Bulgaria forum site (Errors and omissions excluded) – DOWNLOAD | PDF ABS 1 - Click here to download ABS 2 - Click here to download ABS 3 - Click here to download DOWNLOAD ABS Complete Guide Visit Forum Visit Our Friendly Website

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Guide to ABS Diagnostic Trouble Codes (DTC)

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