SC/2008/01 Model : All LCVs, M/HCVs with air brakes Group: 42 January 2008

ALL DEALERS / TASSs

SUBJECT: Introduction of Anti Lock Braking System (ABS) on LCV & M/HCV

vehicles with air brake system.

We are pleased to inform you about introduction of Anti Lock Braking System (ABS) on commercial

vehicles. This is to meet requirement of CMVR regulation which makes Anti Lock Braking System

(ABS) conforming to IS: 11852:2003 (Part 9) mandatory on the following type/class of vehicles

(i) N2 category of vehicles (GVW >3.5 Ton & < 12 Ton) and N3 category of vehicles (GVW more than 12 Tons) other than tractor-trailer combination manufactured on and after the 1st day of October, 2006 meant for carrying hazardous goods and liquid petroleum gas; (ii) N3 category vehicles manufactured on and after the 1st day of October, 2007, which are double decked transport vehicles; (iii) N3 category vehicles used as tractor-trailer combinations which are manufactured on and after the 1st day of October, 2007, they are used as tractor-trailer combinations. (iv) M3 category of buses (vehicle having more than 25 seats and GVW greater than 5 Tons) that ply on All India Tourist permit, manufactured on and after the 1st day of October, 2007

We are attaching details on following topics on ABS for air brake system for your ready reference:

1. Introduction, advantages & Working principle of ABS 2. Suppliers of ABS system 3. ABS –Instructions to User (Operator) 4. General Instructions to Mechanics (Working with ABS) 5. ABS configuration 6. Functions of individual components of ABS 7. Troubleshooting with Blink Code Diagnostics 8. Diagnostic Kit & diagnostic software installation. 9. List of service representatives from Knorr Bremse & WABCO.

Please bring this information to the notice of all concerned in your workshop and educate customers.

1) Introduction, advantages & working principle of ABS Anti Lock braking system is an electronically controlled an add on system, to existing air brake system, used to prevent vehicle skidding during wheel lock under all circumstances of load, tyre/road grip coefficient. The ABS modulates the air pressure in the brake actuator to prevent wheel lock and provides precise vehicle control during braking. Advantages

Improves Stability - Prevents vehicle skidding by avoiding front & rear wheel lock.

Improves Steerability while braking - Helps driver to steer around obstacles during panic braking even on slippery roads.

Shorter stopping distance - Helps to stop the vehicle at lesser stopping distance on dry as well as slippery roads. -

Prevents Jack Knifing - Prevents tractor swinging around the fifth wheel coupling in tractor trailer combination.

Working Principle : ABS consists of an Electronic Control Unit (ECU), pressure modulator valves, sensing rings or pole wheel, wheel speed sensors, Diagnostic switch, Warning lamp and associated electrical wiring. ABS system takes over the control of the air pressure whenever a wheel is about to lock. Each rotating wheel hub is fitted with a Sensing ring or Polewheel. A Wheel Speed Sensor (magnetic sensor) which is mounted on each wheel in close proximity to the Sensing ring or Polewheel generates electrical pulses when the wheel rotates. The electric pulses generated will be in the form of sinusoidal pulses. The frequency at which the pulses are generated is a measure of the wheel speed. The generated electrical pulse signal is sent to Electronic Control Unit (ECU) for processing.

CONTROL

INPUT

Diagnostics Switch

Electronic Control

Unit

Wheel Speed

Sensors

Warning Lamp

Modulator Valve

The ECU after receiving the input signals from all wheel speed sensors processes and compares the sensor signals and detects an impending wheel lock situation. When a wheel is about to lock, the ECU sends an electrical signal to the corresponding modulator valve solenoid (Modulator Valve is fitted in the delivery pipeline coming from dual brake valve), which releases pressure from the brake actuator. When the wheel recovers sufficiently, the brake pressure is reapplied by the ECU by switching off the signal to the modulator valve. This signal is sent to the Electronic Control Unit (ECU) through connecting cables and processed by the ECU. The modulator valve has an additional 'HOLD' state, which maintains pressure in the brake actuator, in order to optimize the braking process. The cycling of the modulator valve is continued till the vehicle comes to a controlled stop. During ABS operation, ECU switches the modulator valve to the above three states (Pressure release, Pressure hold and Pressure re-apply) five six times per second to regulate the brake pressure. 2) Suppliers for ABS System for Commercial vehicles (with S-Cam brakes) There are two suppliers for ABS system for Tata vehicles. i) Knorr Bremse ii) WABCO The working principle, components and their functions for both the suppliers are same. These systems can be identified by the name of supplier on the individual components. Parts for Knorr Bremse & WABCO are not interchangeable between the two suppliers. 3) ABS instructions to User (Operator)

As soon as you switch on the ignition switch, ABS warning lamp on the dash-board should come “ON” for 5 seconds and go “OFF”.

In case ABS warning lamp does not come “ON” momentarily or remains “ON” or comes

“ON” any other time, then it indicates fault in the ABS. In such case, ABS may not function. However the basic brake system will continue to function normally, and will provide normal stopping ability.

In case ABS warning lamp remains “ON”, take the vehicle to the nearest service station for attending to the fault.

In case of vehicle being driven with ABS warning lamp in “ON” condition, applying panic

brake or braking on wet road may result in wheel locking, as it would happen in a vehicle without ABS.

Do not assume that with ABS fitted to a vehicle, it is safe to drive faster or more

aggressively.

Under panic braking conditions, press hard on the brakes and continue to hold it down. ABS does not come into action unless wheel is about to lock during brake application.

Do not switch 'off' the ignition while driving. This makes ABS non-operational.

For any welding job on the vehicle, disconnect all ECU connectors. For removing the electrical connector, do not hold & pull the wires. Hold connector body firmly & then pull it.

4) General Instructions to Mechanics (Working with ABS)

Ensure wheel bearings are adjusted appropriately to ensure that the run-out of the pole wheel is within acceptable limits. Always ensure that the wheel run-out is within specified limits

To push the sensor, use soft non pointed tool (Nylon bar, plastic bar, etc). Do not use any metallic

sharp tool like screw driver

After removing the hub, keep the hubs with the pole wheel facing upwards.

Don’t try repairing any of the ABS parts. Replace with new genuine parts.

ABS prevents vehicle skidding/ pulling by avoiding the front & rear wheel lock. However in case of vehicle pulling to one side during partial braking condition is not due to ABS. The reason could be the basic brake system and investigation for brake pulling on vehicle without ABS system needs to be performed.

When installing ancillary electrical equipment on the vehicle do not use the electrical supply to the

ABS as a power source for the equipment.

Do not connect or disconnect any ABS component with the ignition switched on.

Never remove the battery while engine is running. Voltage spikes caused by the alternator could possibly damage the ECU if they were not absorbed by the battery.

While replacing sensor, replace the sensor bush also and apply recommended grease (part of

spares kit) on Sensor. 5) ABS Configuration

ABS configuration is based on the no of Sensors (S) & Modulators (M) used in the system.

For twin axle 4 x 2 Truck, 4S /4M (i.e. 4 Sensors & 4 Modulators) system is used. - 4 sensors one on each wheel and - 4 modulator valves, one for each wheel brake actuator

For multi axle vehicle 6 x 2 truck, 4S/4M system is used.

- 4 sensors two for front wheels and two for rear live axle wheels - 4 modulator valves, two for front wheel brake actuators one for both rear left brake actuator one for both rear right brake actuator Please refer the following brake circuit diagrams on ABS configuration for Twin axle & Multi axle vehicles.

Twin axle 4 x 2 Truck, 4S /4M system

Multi axle 6 x 2 Truck, 4S /4M system

6) Functions of individual components of ABS: a) Sensing ring or Polewheel Sensing ring or Polewheel is a toothed wheel made of ferrous material. It has 100 evenly spaced teeth. The Sensing ring or Polewheel rotates along with the hub and cuts the magnetic flux generated by the wheel speed sensor. It is fitted on the wheel hub. b) Sensor ('L' type) It is a magnetic sensor (passive type) consists of a permanent magnet and a coil assembly. It generates electrical pulses proportional to wheel speed and transmits to the ECU as a sinusoidal signal It is fitted with a sensor bush in a bracket mounted in the carrier plate as a stationery part. The air gap of < 0.2 mm is maintained between Sensing ring or Polewheel and sensor.

Pole wheel

Wheel Speed Sensor

< 0.2 mm Air Gap

POLE WHEEL AND WHEEL SPEED SENSOR WITH BUSH ON VEHICLE VIEW OF POLE WHEEL & WHEEL SPEED SENSOR

MINIMUM AIR GAP TO BE MAINTAINED BETWEEN POLEWHEEL & WHEEL SPEED SENSOR

Adjustment of Polewheel & sensor Gap The spring-loaded sensor bush is used to hold the wheel speed sensor whilst allowing easy adjustment of the gap between it and the teeth of the sensing ring. The wheel speed sensor can slide in the sensor bush, so the gap between the wheel speed sensor and the teeth of the sensing ring can be set by manually pushing the sensor gently into contact with the teeth and then turning the wheel by hand. After pushing the wheel speed sensor into contact with the sensing ring, while ignition is turned off, the wheel should be rotated by hand. Any run-out of the wheel bearings will cause the teeth of the sensing ring to push away the wheel speed sensor thereby setting the air gap between the two parts.

c) Electronic Control Unit (ECU) ECU acts as the processing unit (brain) of the system. Based on the inputs from the sensors, it computes vehicle speed and deceleration and detects an impending wheel lock situation and sends signals to modulator valve of corresponding wheel which tends to lock. It has built-in self diagnostics and fault logging and warning lamp indication. d) Modulator Valve This is a fast responding electrically operated solenoid valve which modulates the air pressure in the brake actuator. It modulate the air pressure of brake actuator in three states viz. Apply, Hold, Release and operates according to the command from ECU during ABS operation. It is normally open type and acts as a pipe during normal braking. This modulator valve is fitted between dual brake valve and brake actuator in the service line & mounted on chassis long member for front wheels & chassis cross member nearest to rear brake chambers for rear wheels.

e) Sensor Extension Cable

Exhaust (3)

MODULATOR VALVE FOR FRONT WHEEL

A two core cable interfaces the respective wheel speed sensors with ECU. It transmits the signals from wheel speed sensors to ECU. It Connects the ECU and sensors individually. One end with two pin socket connected to sensor. Other end connected to ECU through connector

f) Modulator Valve Cable g) Wiring Harness Two types of harnesses are used namely

i) Cab harness ii) Frame Harness

The cab harness takes care of power supply, warning lamp & blink code switch fitted in the dash board. This may be connected directly to ECU or may be connected through a intermediate harness called pigtail harness. The frame harness connects the ECU with sensors and modulator valves. The cables are made out of polyurethane in order to work reliably in vehicle under chassis environment h) Warning Lamp and Blink Code Switch The Warning Lamp & Blink Code Switch are used for indicating faults in ABS system to the driver. The warning lamp glows whenever the system detects a fault. After rectification of fault, the lamp automatically goes 'off'. When the ABS system detects a fault the ECU will store the fault in the memory. These faults are read through blink codes or using special diagnostic tools. With the ECU powered (‘ignition on’), wait at least 1 second then press the blink code switch once and release. The transmission of the fault blink code is triggered. 7) Troubleshooting with Blink code diagnostics A) Blink code reading method: The blink code will be displayed as short illuminations (blinks) of the ABS warning lamp. The blink code for a fault is split into two series of ‘blinks’ - the first series of blinks (approximately 0.5 seconds each) should be counted to give a “1st Number” and, after a pause of approximately 1.5 seconds, a second series of blinks (approximately 0.5 seconds each) should be counted to give a “2nd Number” (see Fig.) Using the charts on the following pages, it is possible to identify the component and its fault. If there is more than one fault, the next blink code will start approximately 4 seconds later. The ABS ECU is able to store specific codes for every fault detected. The memory can store a maximum of 16 faults. Fault codes for failures that are most recently detected are displayed first and oldest detected faults are displayed last. The blink code sequence, i.e. one blink code per fault, can be repeated by pressing the blink code switch again at the end of the sequence. Note that pressing the blink code switch during the sequence will terminate the transmission of the blink codes. During output of the blink codes, normal operation of the ECU is disabled (i.e. no ABS function).

A three core cable interfaces modulator valve with ECU. (One core for inlet line, one core for outlet line and one core for common ground line). It transmits the signals from ECU to modulator valves during ABS operation. It Connects the ECU and all modulator valves individually. One end with three pin moulded socket to the MV

B) Block Diagram showing blink code reading Method

The number of times the blink code flashes indicates the type of fault that can be referred from the blink code chart. C) Blink code chart WABCO ABS

Block 1 ( Component / Nature of Error) Block 2 ( Location)1 - No faults 1 - No faults2 - ABS Modulator Valve 1 - Front Right (FR)3 - Sensor Air Gap 2 - Front Left (FL)4 - Sensor Short I Open5 - Sensor Intermittence 3 - Rear Right (RR)6 - Sensor, Pole wheel 4 - Rear Left (RL)

1 - Engine control data link7 - System function 3 - Third brake relay short I broken wire

4 - Warning lamp1 - Battery under voltage2 - Battery over voltage

8-ECU 3 - Internal fault4 - Configuration error5 - Ground

Example: 1-1: No Faults; 3-4: Sensor gap rear left is excess

D) Blink Code Chart Diagnostics WABCO ABS

Mode Procedure System response Action Step I. Possible responses: Turn ignition 1. ABS warning lamp comes on No active faults in the ABS. ON. momentarily then goes out, No action required.

indicating system O.K. 2. ABS warning lamp does not light, Inspect wiring. indicating possible wiring fault or Inspect bulb. burned-out bulb. Make necessary repairs 3. ABS warning lamp stays on, indicating: i) Fault or faults in the Continue with blink code diagnostics. system/sensor. (Go to Step II) ii) Faults cleared from ECU. Continue with blink code diagnostics. Sut vehicle not driven. (Go to Step II) Drive vehicle -lamp will goes 'off' when vehicle reaches 7 km/h speed. iii) ECU disconnected Connect ECU.

Step II. ABS warning lamp begins flashing Determine if fault is active or stored: Press and hold two-digit blink code(s). Active error: Lamp will repeatedly blink code Refer blink code chart. display one code. switch for half a Stored error: Lamp will display code

second, then for each stored fault then stop blinking.

release. Faults will be displayed one time only. Step III. First Digit: 1 - 8 flashes, Find definition for blink code on blink Count the Pause (1.5 seconds). code chart. flashes to Second Digit: 1 - 6 flashes, determine the Pause (4 seconds). blink code. Step IV. Active errors. Make the necessary repairs. Turn ignition Repeat Steps I, II, and III until system OFF. O.K. code (1-1) received. Repair and Stored errors. Record for future reference. record faults NOTE: Last error stored is first

DIG

NO

STIC

S

error displayed.

Step V. ABS warning lamp flashes eight All errors are successfully cleared. Turn ignition times quickly and then repeats 2-2. Turn ignition OFF. ON. Clear Faults from memory: Eight flashes not received. Active errors still exist, repeat the

Press and hold steps I through V.

blink code switch for at least three seconds, then

CLE

AR

release.

E) Blink Code Chart With Diagnostics Knorr Bremse ABS

Block 1

Location Block 2

Fault Description

1 --------------------------------------- 1 No faults recorded by the ECU. 2 Wheel speed sensor, front axle,

left side 1 Air gap too big

3 Wheel speed sensor, front axle, right side

2 Missing speed sensor signal at drive off

4 Wheel speed sensor, rear axle, left side

3 Damaged contaminated tooth on sensing ring, erratic signal from speed sensor, check sensing ring alignment and wheel bearing adjustment

5 Wheel speed sensor, rear axle, right side

4 Unstable signal from speed sensor, check sensing ring alignment and wheel bearing adjustment, check wiring for possible source of interference.

5 Loss of speed sensor signal. 6 Sensor wires shorted or broken 8 Pressure modulator valve, front

axle, left side 1 Release solenoid – shorted to battery

9 Pressure modulator valve, front axle, right side

2 Release solenoid - shorted to ground

10 Pressure modulator valve, rear axle, left side

3 Release solenoid wire broken

11 Pressure modulator valve, rear axle, right side

4 Valve ground wire broken

5 Hold solenoid – shorted to battery 6 Hold solenoid – shorted to ground 7 Hold solenoid wire broken 8 System configuration error, check valve and system

wiring and check ECU configuration

10 Pressure modulator valve, valve common ground

10 Shorted to battery, remove X2 Plug from ECU and check for voltage on valve ground connections, replace wiring if necessary

10 Pressure modulator valve, valve common ground

11 Shorted to ground not through ECU or internal valve defect, remove X2 Plug and check resistance between valve ground connections and chassis ground

8) Diagnostic Kit & diagnostic software installation The Diagnostic tester communicates with the ECU (Electronic Control Unit). This tester comprises of a Vehicle interface unit, Custom built application software installed in a Laptop/Desktop Diagnostic tester is used to check for any errors being reported by the ABS system. ECU reports the driver of an error with the help of a diagnostic lamp provided on the dashboard. The details of the errors reported by the ECU can be viewed with the help of a diagnostic kit. Error code and error description can be viewed for trouble shooting. Ignition key has to be ON for Diagnostic tester to read errors from ECU.

Hardware & Software (in CD ) required for the diagnostic kit to be procured from SPD by placing order, detailed part nos for hardware & software are given below. i) Hardware required for ABS Diagnostics

TML Part No Product Name 210322379944 Silicon Engine (For RS232 Port) 210922089901 OBD Cable 210322749944 USB Silicon Engines Interface Note: The hardware for ABS Diagnostic is the same as used for BS-III (VP-37) Channel Partners who had already purchased for BS-III need not buy the Hardware again. ii) Software required for ABS Diagnostics

TML Part No Product Name Description

210322739995 Wabco - ABS Diagnostic software for :- Wabco - ABS

210322739996 Knorr-Bremse - ABS Diagnostic software for :- Knorr-Bremse - ABS

iii) Diagnostic software installation: The Installation CD of the software is supplied with the kit. Installation Procedure:- 1) Insert the CD in the CD Rom 2) Set-up will start running automatically 3) After this the program will guide you for further installation. 4) After successful installation, a short-cut to program will appear on desk-top. 5) When user clicks the short-cut, following screen will appear –

The Application status will be ‘LOCKED’, for unlocking the program user has to log on to the following website

Note: MID and Site code are machine dependent. The software can be installed only in a specific PC/Laptop. The same CD cannot be used to install software in multiple PCs / Laptops.

6) https://ed.tatamotors.com Once you log on the following screen will appear, click on unlock code.

7) After the above step following screen will appear, click on the service request

8) Once you click on service request website will give following screen,

Fill all the data asked by the website and click Save, the site will provide you with INIT code. Please enter that code in the Init code box. (Refer step 5) 9) Then Application status will change to ‘LICENSED’ .Click Continue to start the application.

Part No & Sr. no are written on the Top of the CD

List of service representatives Knorr Bremse

Region Name Location Mobile No. Responsible Area/Region/ZoneNorth Naresh Kumar Delhi 99997 99663 Delhi,Rajsthan,Hariyana,Punjab,Himachal,UP, UA,Jammu East Avijit Mujumdar Kolkata 92305 69728 West Bengal,Jharkhand,Orisa,Bihar,Assam,North East States West Dharmedra Chandratre Pune 98811 38148 Maharashtra,Goa,Gujrat,Madhya Pradesh,ChattisgarhSouth Vijaygopal Balaji Chennai 98405 55826 Tamilnadu,Andhra Pradesh,Karnataka Kerala WABCO Region Name Location Mobile No. Responsible Area/Region/Zone

Murthy K S N New Delhi 98117 99037 North ZoneVenkat Giri S New Delhi 98116 13013 North ZoneVimal Bhat New Delhi 98115 44944 Haryana, Delhi & Uttranchal stateNethaji S Jaipur 99280 84549 Rajasthan stateManoj Garg Jalandhar 98766 25381 J&K, Punjab & HP statesArumugam N Kanpur 99350 47237 UP stateRaghuraman B Kolkata 99031 94444 East ZoneAnanya Chowdhury Kolkata 98319 62993 West Bengal(Except Siliguri), Bihar states & DhanbadSomenath Datta Guwahati 99541 89711 North East states & Siliguri area of WBAmit Kumar Bose Cuttack 98610 45579 Orissa, Jharkhand states (Except Dhanbad)Hussain Mohamed K Mumbai 98215 30441 West ZoneSujit K Tambat Mumbai 98215 30446 West ZoneArumugam B Mumbai 98335 81814 Mumbai & Aurangabad region of MaharashtraJitendra Patel Ahmedabad 98980 39141 Gujarat stateSushil Kumar Maurya Nagpur 98232 87463 Nagpur region of Maharashtra & Chattisgarh stateJameel Babu L Pune 99606 24253 Pune region of MaharashtraDhanasekar M Indore 98260 24824 MP stateSivakumar S Chennai 98409 15870 South ZoneDavid Amalraj A Cochin 98950 48148 Kerala stateRamasubramanian V Chennai 98407 12061 South & North part of TN & ChennaiPunithavelu T Bangalore 98440 71866 Karnataka stateRajendran G S Secunderabad 98492 55172 Telugana & RayalasemaSambasiva Rao S P Vijayawada 98490 86592 East Godavari, West Godavari & Coastal area of APKumar K Salem 98409 78091 Central & Western part of TN

South

North

East

West