BRAKE SYSTEM DEMYSTIFIED. - MechoMedics

Friday, 31 May 2019

BRAKE SYSTEM DEMYSTIFIED.

ANTI-LOCK BRAKE SYSTEM (ABS)
Antilock Brake System (ABS) module on a 2007 Honda Accord.



ABS is a safety anti-skid braking system we can use on various auto motives (vehicle such as car, trucks, buses, tricycles/motorcycles).

ABS is designed in a way that it’s preventing the wheel from locking during braking, which helps to maintain the traction between the tires and the road surface. ABS is a system designed in two ways the "threshold braking" and the "cadence braking"; this is practiced by skillful drivers (FORMULAR 1, NASCAR) that drives vehicle without ABS module by skidding or drifting, but the ABS module is design in a way that is more better than the cadence braking, it operates at a rate that is faster than the cadence braking and it is more effective.
ABS also helps the braking system more active enabling the car to stop on dry and slippery ground even on snow-covered areas and rigidly lose ground level, ABS module increases braking distance and helps in steering control. Before I continue let me quickly talk about Parking brake system.

PARKING BRAKE SYSTEM
Parking brake system is use to maintain the stability of a vehicle on idle or on motion (for emergency purpose).
Rear Hub Assembly and Parking Brake Lining on a 2008 Ford Edge


The parking brake is another system designed to maintain the stability of the vehicle either it’s on motion or not, this system does not depends on the engine to work unlike the ABS module that convert electrical energy to mechanical energy as it regulates Brake Fluid pressure.
The parking brake is designed as a lever that is operated by the driver to lock the rear wheel to prevent motion or reduce speed.
The parking brake system is of two types:
The Handy Parking Brake – This is controlled mechanically.
The Electronic Parking Brake – This has a motor that clings to the wheel to ensure it doesn’t move while it’s activated.
The parking brake is designed with a lever that is operated by the driver; some are locate beside the Transmission Selector or Gear Stick and you will pull the parking brake lever  to activate and drop or release it to deactivate the Parking Brake. Some are designed and placed  beside the Brake PEDAL; and you will simply push the parking brake lever with your foot to activate (as the pedal is depressed down) or deactivate the Parking Brake (as the pedal rises up).
Modern designs utilising Electronic Parking Brake System can be activated with the push of a Button or Switch.
The handy parking brake utilises a cable that is connected to the lever on one end and the other ends of the cable goes directly to the rear wheels which is connected to a parking brake 'shoe' mechanism or Parking Brake Lining that will keep the rear wheels lock under tight frictional force until it is release mechanically.
The Parking Brake when engaged will shows a sign on the Instrument Cluster or Dash-Board by turning on the Parking Brake light (P) in some models it shows BRAKE.
Components of a Parking Brake System
Instrument Cluster.
Parking Brake Lever.
Parking Brake Switch: This activate the warning light.
Parking Brake Lining: This goes from the Brake Pedal to the Brake lining.
Parking Brake Module/AntiSkid Module/Antilock Brake System Module/Brake Control Module.
Parking Brake Motor  or Actuator (In Electronic Parking Brake Systems)- This is close to the rear wheel and lock the rear wheel when the Parking Brake is activated.
ABS MODULE
Ford ABS Module
                     


ABS control module is a microprocessor and control unit that runs diagnostic check on a vehicle ABS system and process information from wheel speed sensor and other hydraulic brake system (the ABS control module is programmed to receive signal from the ABS sensor, that is, Wheel speed sensors); it is responsible for knowing the rate at which the wheels (Front Right-FR,  Front Left-FL, Rear Right-RR, Rear Left-RL) revolve and sends this as a Voltage signal to the ABS control module. The ABS Control Module receives these signals then calculate it and converts this to other digital or analogue signal. For example, the 2008 Toyota Corolla (South African Specification) uses the FR and FL Wheel Speed Sensor signal after processing by the ABS Control Module to operate the speedometer (displaying the speed at which the vehicle moves)  on the Instrument Cluster Assembly;  it also uses this signal when processed by the Skid Control ECU (another name for ABS Module on modern Toyota Vehicles) to regulate the softness or hardness of the Electro Mechanical Power Steering System. Generally ABS modules utilise the signal from the Wheel Speed Sensors to determine which wheel to increase or decrease braking pressure in order to prevent skidding and Wheel Slip.

Functions of an ABS Module 
It helps to calculate the speed of the vehicle through the help of the ABS sensor (wheel speed sensor). It also calculates the speed of  individual wheel, in other to detect faulty sensor and slipping or Skidding wheels.
Better maneuverability: ABS module give the vehicle better drive stability, even when racing and drifting. It also ensure that the vehicle remains steerable (ability to control the steering of the wheels) even during emergency braking, so that collision with obstacles can be avoided in situations that can lead to skidding.
Control of brake force on individual wheel: in modern vehicle the brake force is controlled individually to each wheels. This is advantageous particularly on road surface with different grip, which brings about reduction in YAW Rate moment and tendency to skid.

Symptoms of a Faulty  ABS Module and ABS SYSTEM.
1. ABS warning Light ON.
2. Brake Warning Light ON.
3.ABS Codes are registered in the Diagnostic interface/CAN Communition Codes might accompany such.
4. Unresponsive Brake Pedal (Hard, too soft or spongy feel).
5. Brake Locking Up – ABS is designed specifically to prevent the wheel from locking up during heavy braking, which prevent loss of wheel control. However a faulty module or Brake Master Cylinder can malfunction and cause the brake to locks up even under normal driving conditions.

Types of ABS Sensor (Wheel Speed Sensor)
1. Magnetic Reluctor type –  If the ABS module sends in 5v or less to the Wheel Speed Sensor and it return   6 – 7v or more to the ABS module such is a Magnetic Reluctor type.
2. Digital type – The digital type receive battery voltage 12V  from the ABS module and send less voltage back to the module.
Digital Wheel Speed Sensor for Toyota and Honda 
                      

Symptoms of a Bad ABS Sensor

1. The ABS light comes on: The ABS sensor also sends signal to the anti-lock braking system of a vehicle which in turn sends the speed of the wheel to the ABS module; if the ABS sensor is faulty the ABS module will not receive information from the ABS sensor, when this occurs the ABS module senses a fault and send it to the PCM/ECU which record the fault and notify the Driver by turning on the ABS warning light.
2. MIL may be triggered on by DTC P0500 if such system picks the Vehicle Speed signal from the ABS Sensor as it can lead to driveability and performance concerns.
3. ABS Malfunction and enters a Fail-Safe or Limp-Home mode: With a Faulty Wheel Speed Sensor the ABS will malfunction because it’s not receiving the right information from the ABS sensors in order to know the speed of each wheels and how to reduce or increase the pressure applied in braking them; this may make the front tires of a vehicle to lock up during braking resulting in Skidding or SLIP. As a driver, when you notice this symptoms u should see a technician to diagnose, inspect and fix the fault before your next trip.
4. Traction Control Light or SLIP warning light Illuminates: When the Wheel Speed Sensor on modern Vehicle malfunctions, the traction control light illuminate when the driver turns ON the ignition. This is because the ABS sensor carries out traction control system functions also. So when these warning lights comes on it may be due to a faulty, worn-out, short circuit or open circuit ABS sensor or Wheel Speed sensor.
5. The Speedometer Malfunctions: Since the ABS sensor record the speed of a wheel and send it to the ABS module which calculate the speed and send it to the PCM/ECU which sends it to the instrument cluster and display on the speedometer. Therefore when the sensor is faulty all the module mentioned above won’t get accurate values and wrong display on the speedometer or inoperative speedometer will occur.
6. The affected wheel drags, Slips and makes jerking sounds while turning or moving on surface with varying grip property. The wheel where the sensors is faulty won’t function as other wheels that are functional.

Some Diagnosis Trouble Codes (DTCs) for ABS Sensor Fault:
1. C0035: LF wheel speed circuit malfunction.
Causes: open circuit wheel speed sensor left front.
Dirt or mud,iRon particles on wss
Faulty wiring of wss to ABS module
Faulty Tone ring and Magnetic Hub left front
Dissembled Hub Assembly for 2008 Honda Accord revealing Magnetic Hub and a cut ABS Sensor.

2. C0045: LR wheel speed circuit malfunction.
Causes: open circuit wheel speed sensor left rear
Dirt or mud,iRon particles on wss
Faulty wiring of wss to ABS module
Faulty Tone Ring and Magnetic Hub left rear.

3. C0040: RF wheel speed circuit malfunction.
Causes: open circuit wheel speed sensor Rigth front.
Dirt or mud and iron particles on WSS
Faulty wiring of wss to ABS module
Faulty tone ring and magnetic hub right front.

4. C0041: wheel sensor circuit range/performance
Causes: dirt,mud,iron on WSS
Intermittent failure in WSS.

5. C0046: LR wheel speed sensor circuit range/performance.
Causes: dirt,mud and iron on WSS and
Intermittent failure in WSS

6. C1406: Open or Short in Front Speed Sensor LH Circuit.
Causes: disconnected wss connector
Open circuit or a bridge (short circuit) in wss wiring harness

7. C0050: Rigth Rear wheel speed circuit malfunction.
Causes: open circuit wheel speed sensor Rigth Rear
Dirt or mud and iron particles on WSS
Faulty wiring of wss to ABS module
Faulty tone ring and magnetic hub right rear

8. C0051: LF Wheel Speed Sensor (WSS) range/performance.
Causes: open circuit wheel speed sensor left front.
Dirt or mud,iRon particles on wss
Faulty wiring of WSS to ABS module
Faulty tone ring and magnetic hub left front

9. C1241: Low or High Power supply Voltage.
Causes: Faulty Speed Sensor or open or short in Speed Sensor wiring to ABS Module; Accompanies other ABS Sensor DTCs.

10. C0278: Open circuit in Anti-lock Brake System Solenoid Relay circuit.
Causes:  Electrical wiring fault (open or short circuit) in one or more ABS sensor wiring; Faulty Speed Sensor or open or short in Speed Sensor wiring to ABS Module; Accompanies other ABS Sensor DTCs.

11. C0200: Front speed sensor Right hand circuit.
Causes: disconnected WSS connector
Open circuit or a bridge (short circuit) in WSS wiring harness

12. C0205: Front speed sensor left hand circuit.
Causes: disconnected wss connector
Open circuit or a bridge (short circuit) in wss wiring harness

13. C0210: Rear speed sensor Right hand circuit.
Causes: open circuit wheel speed sensor left front.
Dirt or mud and iron particles on wss
Faulty wiring of WSS to ABS module
Faulty tone ring and magnetic hub left front

14. C1330: open circuit in right front speed sensor Circuit
Causes: open circuit wheel speed sensor Right Front. disconnected WSS connector
Open circuit or a bridge (short circuit) in WSS wiring harness

15.C1331: open circuit in left Front Speed Sensor circuit
Causes: open circuit wheel speed sensor Left Front. disconnected WSS connector
Open circuit or a bridge (short circuit) in WSS wiring harness

16. P0500: Vehicle Speed Sensor A
Causes: faulty Front Left hand or Right hand wheel speed sensor (as it uses them to control the Speedometer), faulty wiring harness of ABS speed sensor to instrument cluster and ABS module.

17. C0210: Rear speed sensor left hand circuit.
Causes: disconnected wss connector,
Open circuit or a bridge (short circuit) in WSS wiring harness

18. U0100: Lost communication with ECM.
Causes: Faulty ABS module; faulty wiring of ABS module to CAN (Computer Area Network) system.

ARTICLE BY: BLESSING OLASODE & MECHOMEDICS TEAM 2019.

1 comment:

  1. This article clarifies why one of our client had an issue on his Instrument Cluster: Symptoms of Tachometer drop and fluctuations, Temperature gauge failure, A/C failure and Speedometer failure. All Pin-point test shows a fault in the CAN wiring caused by Faulty ABS module.

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