Anti-Lock Brake System (ABS) and Stability Control Diagnosis and Testing

For 2012 - 2014 Ford Focus Models

Procedure Revision Date: 03/05/2013

Introduction to Diagnostics

This manual provides diagnostic procedures for the Anti-Lock Brake System (ABS) and Stability Control systems in Ford Focus vehicles (2012-2014 models). It assumes a certain skill level and knowledge of Ford-specific diagnostic practices.

Refer to Diagnostic Methods (100-00 General Information, Description and Operation) for foundational diagnostic information.

Diagnostic Trouble Code (DTC) Chart: ABS Module

The ABS module DTC chart outlines various trouble codes, their descriptions, and recommended actions for resolution. Key components involved include the Hydraulic Control Unit (HCU), wheel speed sensors, and brake pedal switch.

Selected ABS Module DTCs and Actions
DTC	Description	Action Summary
B10DF:46	Master Cylinder Isolation Valve: Calibration/Parameter Memory Failure	Internal ABS module or calibration failure. Clear DTC, repeat self-test. If returns, install new ABS module and HCU assembly. Refer to Hydraulic Control Unit (HCU) (206-09).
C0001:01	TCS Control Channel "A" Valve 1: General Electrical Failure	Internal ABS module failure. Clear DTCs, repeat self-test. If returns, install new ABS module and HCU assembly. Refer to Hydraulic Control Unit (HCU) (206-09).
C0031:4A	Left Front Wheel Speed Sensor: Incorrect Component Installed	Incorrect wheel speed sensor type. Verify correct sensor (part number stamped). If incorrect, install new sensor. Drive vehicle > 20 km/h (12 mph) for self-test. If correct sensor installed, install new ABS module and HCU. Refer to Front Wheel Speed Sensor (206-09).
U3003:16	Battery Voltage: Circuit Voltage Below Threshold	Voltage supplied to ABS module falls below 10 volts. Possible causes: fuses, wiring, ABS module, charging system. Refer to Charging System (414-00).

Diagnostic Trouble Code (DTC) Chart: Steering Angle Sensor Module (SASM)

The SASM DTC chart provides details for issues related to the steering angle sensor, which is crucial for stability control.

Selected SASM Module DTCs and Actions
DTC	Description	Action Summary
C1B00:49	Steering Angle Sensor: Internal Electrical Failure	Incomplete/improper flash programming or internal failure. Check service history, repeat programming, or install new SASM. Refer to Steering Angle Sensor Module (SASM) (211-05).
C1B00:85	Steering Angle Sensor: Signal Above Allowable Range	Steering wheel angle PID displays > 360 degrees. Set front wheels straight, monitor PID. If PID is 0, clear DTC. If > 360, remove SASM, manually adjust to 0 degrees, reinstall.

Symptom Chart: ABS and Stability Control

This section addresses common symptoms and their possible causes, guiding technicians to the appropriate diagnostic actions.

Selected Symptoms and Possible Causes
Condition	Possible Sources	Actions
A module does not respond to the scan tool	Fuse, wiring/terminals/connectors, ABS module concern, SASM concern	Refer to Communications Network (418-00).
The brake warning indicator is always or never on	Low brake fluid level, brake fluid level sensor, parking brake applied/switch, brake booster vacuum sensor, IPC concern, ABS concern	Retrieve and diagnose all ABS module DTCs. If none, diagnose brake warning indicator. Refer to Instrumentation, Message Center and Warning Chimes (413-01).
The stability/traction control OFF indicator (sliding-car OFF symbol: ⛌) is always on	IPC concern, ABS concern, SASM concern	Retrieve and diagnose all ABS module and SASM DTCs. If none, diagnose warning indicator. Refer to Instrumentation, Message Center and Warning Chimes (413-01).

Normal Operation and Fault Conditions Overview

Anti-Lock Brake System (ABS) Module

The ABS module, hydraulic pump, and solenoid valves require an operating voltage between 10 and 17 volts, supplied from the Battery Junction Box (BJB). A single ground circuit is located in the engine compartment wiring harness. Issues like excessive resistance, open circuits, discharged battery, or an inoperative charging system can cause the ABS module to set a DTC.

Wheel Speed Sensors

Active wheel speed sensors generate a square wave signal proportional to wheel speed, sent to the ABS module. Each sensor connects via two wires: one for voltage supply and one for signal return. The ABS module performs a self-test by sending a reference voltage through the sensors. Damage to the encoder (tone wheel), wheel bearing, or sensor, or incorrect tire size/air gap can lead to erratic signals and DTCs.

Brake Pedal Switch

The ABS module receives brake pedal switch input from the PCM via the High Speed Controller Area Network (HS-CAN). This input is compared against wheel speed sensor data to validate brake pedal input. An incorrectly installed switch or a driver resting a foot on the pedal while accelerating can cause signal plausibility issues.

Stability Control Sensors (RCM)

The Restraints Control Module (RCM) measures vehicle yaw rate, lateral acceleration, and longitudinal acceleration, sending this data to the ABS module over a private HS-CAN. Internal sensor failures, RCM issues, or communication network problems can cause the ABS module to set DTCs related to stability control sensor signals.

Steering Angle Sensor Module (SASM)

The SASM monitors steering wheel rotation speed, angle, and direction, transmitting this information to the ABS module via the HS-CAN. Failures in the HS-CAN, SASM itself, or its internal sensors can lead to DTCs. Incorrect installation or calibration can also cause issues.

Communication Network (CAN)

Various modules (ABS, SASM, BCM, PCM, TCM) communicate over the High Speed Controller Area Network (HS-CAN) and Medium Speed Controller Area Network (MS-CAN). If modules do not receive expected messages within specified timeframes, DTCs are set. This can be due to module failures, circuit failures, or excessive network load.

Pinpoint Tests

The document details numerous "Pinpoint Tests" (e.g., Test A, Test B, Test C, etc.) which provide step-by-step diagnostic routines for specific DTCs or symptoms. These tests involve using diagnostic scan tools, checking electrical circuits, inspecting components, and performing self-tests to isolate and resolve issues.

Examples of Pinpoint Tests include:

Pinpoint Test A (U3003:16): Addresses battery voltage below threshold concerns.
Pinpoint Test B (Wheel Speed Sensor Erratic Signal DTCs): Guides through checking tires, wheel speed sensor damage, mounting, and wheel bearing/encoder.
Pinpoint Test C (C0040:64): Focuses on brake pedal switch signal plausibility failure.
Pinpoint Test D (U0140:00): For lost communication with the Body Control Module (BCM).
Pinpoint Test E (Traction Control System Cannot Be Disabled - GDI Engine): Verifies MyKey® settings and communication.
Pinpoint Test F (U3003:17): Addresses battery voltage above threshold concerns.
Pinpoint Test G (Stability Control Sensor Signal Failure DTCs): Checks communication network and RCM.
Pinpoint Test H (C0020:01, C0020:1C, C0020:71): Diagnoses ABS pump motor control issues.
Pinpoint Test I (C0040:87 or U0100:00): For missing brake pedal switch messages or lost communication with PCM.
Pinpoint Test J (U0101:00): For lost communication with TCM.
Pinpoint Test K (U0126:00): For lost communication with Steering Angle Sensor Module.
Pinpoint Test L (U3003:62 - SASM): Addresses SASM battery voltage signal compare failure.
Pinpoint Test M (Steering Angle Sensor Module (SASM) Signal Failure DTCs): Verifies SASM calibration and sensor values.
Pinpoint Test N (C1A41:64): For clutch pedal sensor signal plausibility failure.
Pinpoint Test O (Wheel Speed Sensor Electrical Fault DTCs - Front): Checks for electrical faults in front wheel speed sensors.
Pinpoint Test P (Wheel Speed Sensor Electrical Fault DTCs - Rear): Checks for electrical faults in rear wheel speed sensors.
Pinpoint Test Q (U3003:62 - ABS Module): Addresses ABS module battery voltage signal compare failure.
Pinpoint Test R (U0300:00): For internal control module software incompatibility.
Pinpoint Test S (Traction Control System Cannot Be Disabled - GTDI Engine): Verifies MyKey® settings and ESC switch operation.

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