As Easy as A.B.S

Safety concerns have been driving the automotive sensor market towards newer and more effective technology.

The 1990s saw safety emerge as a major consideration and features such as traction control, stability control systems and anti-lock braking system (ABS) have been applied across a wide sector of the industry. Since 2012, the fitment of ABS as a standard has been mandated for all passenger cars and light vehicles.

Cambiare, the vehicle electronics specialist, has a portfolio of over 350 ABS sensors. It is adding a further 100 parts to its range soon to cover applications like Vauxhall Insignia 2.0 (07/2008>), Renault Megane 1.6 (09/2002-02/2008) and Volvo V70 2.0 (03/2010>).

THE ABS PRINCIPLE

ABS is a safety system that prevents wheel lock during braking. This enables the driver to maintain steering control and avoid uncontrolled skidding.

ABS also provides improved vehicle control and decreased stopping distances on dry or slippery surfaces. However, ABS will not offer any benefits on ice/snow-covered roads as there isn’t enough traction between the tyre and the road.

Not only does the modern ABS prevent wheel lock under braking, it may also electronically control the brake bias towards all brakes. This function, depending on its specific capabilities and implementation, is known as electronic brake force distribution (EBD). Other functions of the anti-lock braking system can include traction control, emergency brake assist and electronic stability control (ESC), depending on the system and manufacturer.

ABS SENSORS AND THEIR WORKING

ABS uses a wheel speed sensor, commonly called an ABS sensor, to monitor the rotational speed of each wheel. These sensors send the information to an electronic brake control module (EBCM), which in turn controls the operation of the electrohydraulic unit that regulates the flow of brake fluid to each wheel brake.

Although there are numerous variations of ABS sensors, they all fall into two categories:
• Inductive ABS sensors (Passive) – when no additional power supply is required
• Hall Effect ABS sensors (Active) – when a power supply is connected to the sensor

INDUCTIVE ABS SENSOR (PASSIVE)

Essentially, the sensor comprises of a coil wrapped around a magnet. This sensor is positioned close to the ‘reluctor ring’ which consists of a toothed ring mounted on the wheel hub. Each time a tooth of the ring passes the sensor, a small electrical voltage is induced within the copper coil. This voltage is transmitted to the ECU in the form of a sinusoidal signal (or a sine wave) that is used to calculate the vehicle’s wheel speed.

This is a basic form of an ABS sensor and is susceptible to interference or false cycling from factors such as a corroded reluctor ring or debris on the sensor head. The inductive ABS sensor does not start working until the vehicle has achieved a speed of 3-5mph.

HALL EFFECT ABS SENSOR (ACTIVE)

A Hall Effect sensor is an active sensor that uses the addition of a power supply to create a digital output. The power supply is connected to a Hall Effect element creating a consistent current flowing through it. When the element is subjected to a magnetic field of sufficient strength and polarity created by the passing reluctor ring, it deflects the current across the Hall-element creating an on/off voltage signal.

This type of sensor will start working straightaway and doesn’t suffer from false cycling. It is more sensitive and accurate than a passive sensor, allowing systems such as electronic stability programmes to be incorporated in modern ABS systems.

In both passive and active ABS sensors, a signal (either sinusoidal or digital) is transmitted to the ECU that uses the data to determine the wheel speed and evaluate whether the ABS should intercede to control braking. The vehicle is at its maximum stability when all the four tyres have traction and are spinning at the same rate.

MALFUNCTIONING ABS SENSOR

Wear and tear is the most common reason for an ABS sensor failure on any vehicle. The position of the sensor and constant movement of the vehicle’s steering and suspension make it vulnerable to detrimental factors such as:

• heat from the brakes
• vibrations
• threat of dirt and moisture ingress

Generally, a scan tool is used to diagnose an ABS sensor problem. A digital multi-meter or oscilloscope reads the pulse and accurately displays the ABS wave pattern. A code reader can be used to read trouble codes relevant with the specific fault. Cambiare recommends that the vehicle should be driven a short distance following the replacement of a faulty sensor for the system to recognise the new part. Failure to do so may result in the fault code not clearing, giving the impression that the new part is faulty too.

THE CAMBIARE ADVANTAGE

Owing to the conditions in which the ABS sensor needs to work in and the stress it undergoes, a quality replacement sensor is essential to ensure longevity. With an emphasis on quality and continuous range development, Cambiare offers an extensive portfolio of OE-quality and 100% BER compliant ABS sensors.

The parts are produced in state-of-the-art facilities, conforming to international manufacturing standards, including TS16949 and ISO9001:2008. This ensures that these sensors deliver increased reliability when compared to other products available in the independent aftermarket.

FEATURES AND BENEFITS

All Cambiare sensors are thermal, shock, vibration and temperature tested to ensure optimal performance in the most difficult conditions and offer:

• better tolerance against heat and vibrations
• more resistance to shock and moisture
• resistance to salty conditions
• better performance under high-stress conditions

SUMMARY

• ABS sensors help the ABS system in monitoring the rotational speed of wheels and improve traction.
• Cambiare, the engine management specialist, offers a range of 350 ABS sensors, which:
– are provided by OEM or BER compliant aftermarket suppliers
– offer 2 years or 30,000 miles warranty, whichever comes first
• User-friendly website www.cambiare-ve.com provides:
-online catalogue with accurate and detailed listing of parts
-easy search options by vehicle application, OE numbers and cross-reference
-useful technical information, tips & tricks and the latest news
• Dedicated technical helpline: 0845 543 8280*
• Campaign and marketing collateral available on request.
• Same/next-day delivery from FPS.

*Calls to 0845 numbers cost 3 pence per minute, plus your telephone company’s access charge.

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INFORMATION

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