EBS Training

TRAINING TIPS AND TACTICS

Truck Air and Brakes - Management

1

2

General information

EBS general description Modulators Footbrake valve Back-up mode Port numbers Basic fault finding logic Use IMPACT

EBS Generation 2

Main components Axle configuration Circuit diagram - general Circuit diagram - air pipes Circuit diagram - wires/ datalinks EBS ECU location and plugs Wheel speed sensor (WSS) Lining wear sensor (LWS) Footbrake valve

Contents 11 13 15 15 17 21 23

27 29 32 35 37 39 41 45 47

EBS Generation 2 - cont.

Modulator - single channel Modulator - twin channel Modulator - trailer Automatic brake adaptation Brake Compatibility System (BCS) Load sensing Traction Control System (TCS) Trailer Brake System (TBS) Differential lock Test equipment Footbrake valve test Modulator test EBS ECU test VCADSPro - EBS Truck/trailer ABS lights and symbols ABS test

49 57 59 60 63 65 67 69 71 71 71 73 75 77 77

3

EBS Generation 3

Axle configuration Main differences Software levels Electronic Stability Program (ESP) Hill start aid Automatic differential lock Status recorder Emergency Brake Assist (EBA) Drag torque control Wake-up signal Brake temperature warning Brake Blending Function (BBF) Wheel brake monitoring Load sensing External Brake Demand (EBA)

80 83 86 86 89 91 93 93 93 95 96 96 97 97 98

EBS Generation 3 - cont.

Brake force distribution/ slip control EBS ECU location and plugs Modulators ABS control valve Multi-channel systems Three channel 4 x 2 Three channel 6 x 4 Four channel 6 x 2 pusher Four channel 8 x 4 Five channel 8 x 2 Footbrake valve test Modulator test Trailer modulator test EBS ECU test Resetting learning parameters

99 101 103 105 110 113 115 117 119 121 123 125 127 129 131

4

Introduction About this Pocket guide

This guide is intended as a memory jogger for the knowledge you have gained during your training course. The guide includes a summary of the material covered in:

Truck Air and Brakes - Management

5

Danger, Warning, Caution & Note

In this guide, risk of injury or damage is indicated by the following headings: DANGER - indicates a risk of serious personal injury or death. WARNING - indicates a risk of personal injury, or severe product damage. CAUTION - indicates risk of product damage. Note - draws attention to special methods or particular features. Read and implement all DANGER, WARNING and CAUTION instructions.

6

Replacement parts

When replacement parts are required, it is essential that only Volvo genuine parts are fitted. If Volvo genuine parts are not used: - safety features embodied in the vehicle or components may be impaired. - performance and/or operation of the vehicle or components may be adversely affected. - Volvo warranty terms may be invalidated.

7

Specification

Volvo are constantly seeking ways to improve their products, and alterations take place accordingly. Whilst every effort has been made to ensure the accuracy of this guide, it should not be regarded as an infallible guide to current specifications of any product. Neither Volvo, nor the supplier of this guide shall, in any circumstances, be held liable for inaccuracy or the consequences thereof.

Copyright

C

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, transmitted or copied without written permission from Volvo Truck & Bus Ltd. Volvo Truck & Bus Ltd. 2005

8

General information 9


ECU

37

11 12

37 S

33 Air supply - constant 12 bar Modulated air pressure Electronic control signal

33

P

37a 33

10 10. Footbrake valve 11. Front circuit air tank 12. Rear circuit air tank 33. Brake chambers 37. Front brake modulators

37a. Rear brake modulator ECU. Electronic Control Unit

10

General information EBS/ECBS - general description

Changing the title ʻElectronic Brake Systemʼ (EBS) to ʻElectronically Controlled Brake Systemʼ (ECBS) provides a more accurate start point for a description of the system. The brake system remains mainly an ʻairʼ system - the pads are still applied by air pressure via conventional brake chambers. The crucial difference is that, with an EBS system, air pressure, and supply and release to and from the brake chambers, is electronically controlled. Electronic control is largely responsible for providing one of the main advantages of EBS - faster application and release, with a consequent reduction in stopping distance. Faster response is also aided by the fact that the electronically controlled modulator valves, which control pressure and supply, are located very close to the brake chambers, and have a constant air supply direct from the air tanks. The concept is shown in the simplified diagram above.

11

General information

1

2 12

General information Modulators 1 - single channel 2 - twin channel

ABS/TCS and load sensing

The modulators are basically solenoid controlled relay valves, which can modulate - vary - the air pressure supplied to the brake chamber connected to them. They are normally controlled by electronic signals from the EBS ECU. The pressure is modulated according to the value of the applied electronic signal. The value of the signal is calculated by the EBS ECU in response to signals it receives from other sensors importantly, individual wheel speed and vehicle load. The modulator is, therefore, providing ABS/TCS and load sensing control, without the need for the separate valves used in non-EBS systems. If there is an electrical fault, the modulators are controlled by air pressure from the footbrake valve.

13


ECU

37

33 11

37a

12

37 S

33

10

P

51

Air supply - constant 12 bar Air supply - reduced pressure Modulated air pressure Electronic control signal

51

10

33

10. Footbrake valve 11. Front circuit air tank 12. Rear circuit air tank 33. Brake chambers 37. Front brake modulators

37a. Rear brake modulator 51. Pressure limiting valves ECU. Electronic Control Unit

14

General information

Footbrake valve

Back-up mode

The footbrake valve is a conventional two part air valve, with the addition of two potentiometers. The potentiometers supply electrical signals to the EBS ECU, which are proportional to footbrake movement - i.e. ʻdriver demandʼ. When EBS is operating without fault, the electrical signal reaches the modulator instantaneously, and is the only driver demand signal used by the modulator. Air pressure is still delivered from the footbrake valve, but electrical control takes priority. However, if an EBS fault occurs, the system goes into ʻback-upʼ mode, in which the driver demand signal reverts to air pressure from the footbrake valve - as in non-EBS systems. The footbrake valve is supplied with air at reduced pressure via pressure limiting valves (51).

15

General information Back-up mode

Note: when the system is operating in back-up mode, the following functions are not available: Anti-Lock Braking (ABS) Traction Control (TCS) Tractor/trailer brake adaptation (BCS) Load sensing Because ABS and load sensing are not available, braking is biased towards the front axle and trailer brakes. When the footbrake pedal is pressed air, at up to 2 bar pressure, is delivered to the front brake circuit and trailer circuit, before air is delivered to the drive axle circuit. This bias reduces the risk of a jack-knife occurring.

16

General information Port numbers - general

Valve ports generally conform to a common numbering sequence: Port 1 - Supply, normally from a tank. If there is more than one supply, a second number is used - e.g. 11, 12. Port 2 - Delivery, to another component. If there is more than one delivery, a second number is used - e.g. 21, 22. Port 3 - Exhaust, to atmosphere. Port 4 - Signal to the valve to operate. Port 0 - To atmosphere - on the compressor from the air inlet. Port 5 - To the re-generation tank.

17


11

Note: Other ports 11 and 12 to pressure gauges. For EBS, the front circuit is the primary circuit.

21 22

11 - from front tank (11) 12 - from rear tank (12) 21 - to front modulators 22 - to rear modulator S - Secondary system P - Primary system

S

12

21 P

11

22 12

Footbrake valve ports

18

General information

Advantages of EBS

In common with other vehicle systems - e.g. engine management - once electronics is introduced, it becomes possible, or easier, to take account of additional factors which affect the final desired result. In summary, EBS allows easy interaction with: - EMS, power reduction in safety critical circumstances. - engine brake or retarder, retardation assistance. - transmission control system. - pad/lining wear sensing, distributed brake force for more even wear. Simplified use of: - vehicle load signal, no separate load sensing valve. - individual wheel speed signals, no separate ABS/TCS valves (except certain Gen. 3 configurations).

19

General information Air is leaking from a valve.

Disconnect pipe(s) from outlet port(s) 2

Note: The valve may need to be operational. Operate park/footbrake

Is air leaking from the pipe ?

Yes

No

The component connected to the pipe is leaking. Trace the pipe back

Renew the valve

20

General information Basic air brake fault finding logic

Air pressure units

The chart above shows the basic logic to be applied when air is leaking from a valve.

Air pressure can be expressed in ʻbarʼ or ʻPascalʼ: 1 bar = 100 Kpa (KiloPascal) 10 bar = 1 mPa (MegaPascal)

21

General information

Use IMPACT

To ensure that you are using the latest service information - especially specifications - always get your information via IMPACT: Group 56 and 59 (content varies according to ʻInformation Typeʼ selected)

22

General information IMPACT Information groups

Group 56 = modulators, footbrake valve Group 59 = ECU

Check list A - ECU EBS signal descriptions Check list B - modulators EBS signal descriptions Check list C - footbrake valve Comments to check list C Brake pressure EBS

59 59 56 56 56 56 56

23

24

Electronic Braking System - Generation 2 25

1

5

9 6

7

2 6

3

6 7

4

8a

1 9 10 11

5

10 7

3

2

7

6

8b

2 4

12

8a

7 11 6 8b

12

26

EBS - Gen. 2 EBS Gen. 2 components

1. EBS Electronic Control Unit (ECU) (9082) 2. Single channel modulator* (6076) 3. Twin channel modulator (6076) 4. Trailer modulator (6076) 5. Footbrake valve (6077) 6. Wheel speed sensor (7057) 7. Brake lining wear sensor (7085) 8a. Load sensor (7064) - Signal to EBS ECU via ECS ECU data link. 8b. Load sensor (7072) - with leaf springs. 9. Trailer brake switch (1157) 10. Traction Control (TCS) switch (1155) 11. Low pressure switch - park tank (2075) 12. Plug socket for ABS/EBS (79) ISO socket dedicated to EBS - 7 pins * Note: On version 2 trucks with lift axle, an extra single channel modulator is used to control both N/S & O/S brakes on the lift axle. 27

EBS - Gen. 2

1

1

1

2

3

2

3

2

3

6x2 Tag

6x2 Pusher

6x4 28

EBS - Gen. 2 Axle configuration Gen. 2

Service information in IMPACT refers to the axles, and to components attached to the axles: 1 - is always the front axle 2 - is always the drive axle 3 - is either a tag or pusher axle

29

EBS - Gen. 2 11

High pressure 12 bar Reduced pressure

P21

12

14 51

HPF

51

P11 P23

52a 57 56

P1

24

P22 P12 P24

HPR

S P

10

30

HPF P21

33

P1

P22

24

P11

P12

13 S P

10

25a 25

33

SU EM CO SE

P24

P23

37 37

37b

30

HPR

31

37a 33

33

EBS Gen. 2 circuit - 4 x 2

31

EBS - Gen. 2 Main components - EBS 4 x 2

The main components of the EBS circuit are: 10. Footbrake valve 11. Front circuit air tank 12. Rear circuit air tank 13. Park brake tank 14. Wet tank 24. MCPV (7 port) 25. Distributor manifold 25a. Filter 33. Brake chamber 37. Single channel modulator 37a. Twin channel modulator 37b. Trailer modulator 38. Pressure sensor 51. Pressure limiting valve 52a. Overflow valve (6.7 - 7.0 bar) 56. Air bellows 57. Air suspension valve

HPF - high pressure from tank (11) direct to front modulator valves HPR - high pressure from tank (12) direct to rear modulator valve SU - supply, trailer EM - emergency, trailer CO - control, trailer SE - service, trailer

32

EBS - Gen. 2 EBS Gen. 2 was the first version to be released to the UK market in year 2000.

33

EBS - Gen. 2

37

33

1

33

10 12

13 24 37

51 33

14

11

37a

37b

51

33 T 34

EBS - Gen. 2 Gen. 2 - air pipes

1. Compressor 10. Footbrake valve 11. Front circuit air tank - 12 bar 12. Rear circuit air tank - 12 bar 13. Park brake tank - 8.5 bar 14. Wet tank - 12 bar 24. MCPV (7 port) 33. Brake chamber 37. Single channel modulator 37a. Twin channel modulator 37b. Trailer modulator 51. Pressure limiting valve - 8.5 bar T. To trailer

35

EBS - Gen. 2 33

WS

J1939 - J1587 ISO 11992

SS

37 CAN

33

WS

SS

CAN ECU

10 CAN

37 WS

33

SS

CAN

37a 37b

38

33

WS

SS

56 36

EBS - Gen. 2

Gen. 2 - wires/ data links

10. Footbrake valve 33. Brake chamber 37. Single channel modulator 37a. Twin channel modulator 37b. Trailer modulator 38. Pressure sensor 56. Air bag CAN. Controller Area Network ECU. EBS Electronic Control Unit WS. Lining wear sensor SS. Wheel speed sensor J1939. Fast data link J1587. Slow data link ISO 11992 - data link, trailer with EBS

37

EBS - Gen. 2

Elec. 98 trucks Version 2 trucks 38

EBS - Gen. 2 EBS ECU location

Plug colours and markings

The illustrations above show the location of the ECU on Elec. 98 and Version 2 trucks. Version

Elec. 98

Version 2

EBS Gen.

2

2

Black

X1

EBA

Yellow

X2

EBB

Green

X3

EBC

Purple

X4

EBD

39

EBS - Gen. 2 1

2

40

EBS - Gen. 2

Wheel Speed Sensor (WSS)

Attached to each wheel hub is a toothed ʻpoleʼ wheel (1). Located very close to the wheel is a sensor (2). The sensor is an inductive signal generator, which has a permanent magnet surrounded by a coil. As each wheel tooth passes the sensor tip, an AC voltage pulse is induced in the sensor coil. As the wheel rotates faster, more pulses are generated. The number of pulses in one second is the signal ʻfrequencyʼ. The frequency, and voltage, of the signal are directly related to the speed of the wheel. The voltage is also directly related to the ʻair-gapʼ between the wheel teeth and sensor tip: wider gap = lower voltage. A correct gap is particularly important for reliable low speed operation.

41

EBS - Gen. 2

Frequency

Voltage

Low speed High speed Typical form of alternating voltage generated by an inductive sensor 42

EBS - Gen. 2 Wheel Speed Sensor (WSS)

The induced signal is fed to the ECU of the adjacent modulator and, from there, to the EBS ECU. Using the speed signal, the EBS ECU can calculate: - speed of each wheel - road speed - acceleration - deceleration Calculations are based on the formula: Force = Mass x Acceleration Rearranged: Acceleration = Force/Mass The speed signal is one of the factors used by the EBS ECU to calculate the brake force to be applied. It is also used during ABS/TCS control, and by other ECUʼs, via the J1939 data link.

43

EBS - Gen. 2

4.1 V

0.5 V 20 mm

0 mm 44

EBS - Gen. 2 Lining Wear Sensor (LWS)

Even lining wear

Each brake calliper has an electronic wear sensor which detects the average thickness of both brake pads. The sensor produces a voltage varying between 0.5 V and 4.1 V depending on how much pad thickness remains. Each time the footbrake is pressed a reading is taken. When less than 20% of the pad lining remains, the YELLOW information lamp is lit, and the message ʻcheck brakesʼ is displayed. Using information from the sensors, brake pressure is adjusted between the front and rear axles, so that lining wear is as even as possible. Pressure adjustment does not alter the total braking force. Stored values for each wheel can be read using VCADS. Note: Using VCADS, the sensors must be recalibrated when new pads are fitted.

45

EBS - Gen. 2 4 3 1 2

11 12

21 22

5V SM2 AGNI SM1 4.5V

SM2

0.5V Off

SM1 Full

46

EBS - Gen. 2 Footbrake valve

The EBS footbrake valve is a conventional two part air valve, with the addition of two potentiometers. The pot. output voltage varies in proportion to the amount of pedal depression. The voltage from each pot. is fed to the EBS ECU, and is one of the factors used by the ECU to calculate the brake force to be applied. Any detected inconsistency in either voltage will cause a fault to be recorded, and the system will revert to ʻback-upʼ mode. 5V. Controlled voltage supply to potentiometers SM2. Pot. output signal - 4.5v - 0.5V AGNI. Common earth SM1. Pot. output signal - 0.5V - 4.5V 11. Front circuit inlet - 8.5 bar 12. Rear circuit inlet - 8.5 bar 21. To front circuit 22. To rear circuit 47

EBS - Gen. 2

PS WSS

LWS

CAN

WSS

ECU IV

OV

BV

PS

4 11

1

37 F

2

RLV 3

33

48

EBS - Gen. 2

Single channel (wheel) modulator

1. High pressure direct supply 2. Modulated delivery 3. Exhaust 4. Back-up supply BV. Back-up valve IV. Inlet valve OV. Outlet valve PS. Brake line pressure sensor RLV. Relay valve

F. Filter BU. Back-up air supply WSS. Speed sensor signal LWS. Wear sensor signal CAN. CAN + voltage supply 11. Air tank 33. Brake chamber 37. Modulator

Each modulator has several internal valves and an ECU. Via a data link, the modulator ECU receives signals from the EBS ECU, which determine the brake pressure to be applied to the connected brake chamber. The modulator ECU also receives signals from sensors wheel speed, lining wear, vehicle load, and transmits these signals to the EBS ECU, where they are used to calculate the pressure signal sent back to the modulator ECU.

49

EBS - Gen. 2

PS WSS

LWS

CAN

WSS

ECU IV

OV

BV

PS

4 11

1

37 F

2

RLV 3

33

50

EBS - Gen. 2

Single channel (wheel) modulator

In the illustration above, the ignition is on so the modulator has power. The footbrake pedal is not pressed. The pressure sensor monitors the pressure in the brake chamber supply line. The modulator ECU is receiving wheel speed and lining wear information from the sensors. IV is not energised and is closed. BV is not energised and is open. OV is not energised and is closed. RLV is fed with air from tank (11), but has no pressure signal.

51

EBS - Gen. 2

PS WSS

LWS

CAN

WSS

ECU IV

OV

BV

PS

4 11

1

37 F

2

RLV 3

33

52

EBS - Gen. 2

Single channel (wheel) modulator brake applied

In the illustration above, the ignition is on so the modulator has power. The footbrake pedal is pressed. The potentiometers have signalled driver demand to the EBS ECU, and a pressure signal has been calculated and sent to the modulator ECU. IV is energised and is open. BV is energised and is closed. OV is not energised and is closed. RLV now has a pressure signal from IV, so the required pressure is delivered to the brake chamber, and sensed by PS.

53

EBS - Gen. 2

PS WSS

LWS

CAN

WSS

ECU OV

IV BV

PS

4 11

1

37 F

RLV

3

2

33

54

EBS - Gen. 2

Single channel (wheel) modulator back-up

If the electronic control system fails, the modulators operate in back-up mode. Air pressure from the footbrake valve is fed to the back-up valve (BV) and relay valve (RLV). Braking force is now controlled by the driver.

55

EBS - Gen. 2 10 WSS LWS1/3 LSV1(2) WSS

WSS LWS2/4 CAN

WSS

ECU OV

BU PS 21

33

IV

BV

37 BV

RLV

IV

RLV F

OV

PS

22

33 12

56

EBS - Gen. 2 Twin channel (axle) modulator

BV. Back-up valve IV. Inlet valve OV. Outlet valve PS. Brake line pressure sensor RLV. Relay valve F. Filter BU. Back-up air supply

WSS. Speed sensor signal LWS. Wear sensor signal CAN. CAN + voltage supply 12. Air tank 33. Brake chamber 37. Modulator

Rear axles each have a twin channel modulator, which is basically two single channel modulators in a common housing. Operation of each channel of the twin channel modulator is identical to that of the single channel modulator.

57

EBS - Gen. 2

CAN

ECU IV

BV 41 13

PS

F DV

43 42

OV

RLV

21

22

37b

58

EBS - Gen. 2 Trailer modulator

BV. Back-up valve IV. Inlet valve OV. Outlet valve DV. Dump valve RLV. Relay valve PS. Brake line pressure sensor F. Filter CAN. CAN + voltage supply

13. Park brake air tank 21. Trailer supply line 22. Trailer control line 37b. Trailer modulator 41. Service brake front circuit 42. Service brake rear circuit 43. Park brake circuit

The trailer brake modulator is used with trailers which do not have an EBS brake system. The modulator supplies compressed air to the trailer brake system, and controls the trailer brake pressure. Like the other modulators the trailer modulator is normally controlled by the EBS ECU, and it also has a back-up function. Note the additional air supply from the park brake hand control valve to port 43. The park brake function operates in the same way as a conventional trailer brake control valve.

59

EBS - Gen. 2

Automatic brake adaptation Brake Compatibility System (BCS)

Automatic brake adaptation ensures optimum brake force distribution between tractor and trailer. This results in more stable braking and more even lining wear. The modulator can adjust the trailer brake pressure + 1.5 bar to - 0.5 bar in relation to the tractor brake pressure. These pressures cannot be altered. Adjustment takes place automatically when the vehicle is moving.

Modulator repair

Limited overhaul of the modulators is possible using repair kits - refer to IMPACT for parts and repair information.

60

61

EBS - Gen. 2

62

EBS - Gen. 2 Load sensing

The EBS system does not have a load sensing valve. Because the pressure in the rear axle air bags varies as vehicle load varies, this pressure is used as a reference for vehicle load. A sensor, in the Electronically Controlled Suspension (ECS) system, detects the varying pressure, and sends a variable voltage signal to the ECS ECU. The EBS ECU can read this signal via the data link. The signal is used by the ECU to calculate the required brake force, and distribution between the front and rear wheels.

63

EBS - Gen. 2

64

EBS - Gen. 2

Traction Control System (TCS)

Terrain TCS

The relative speed of all road wheels is constantly monitored by the EBS ECU. If a drive wheel loses grip and starts to spin, the sudden increase in speed, relative to non drive wheels, is detected. At road speeds less than 40km/h, engine power is reduced, and the brake on the spinning wheel is applied, and traction is transferred to the non spinning drive wheel. At road speeds above 40km/h only engine power is reduced. In certain conditions - e.g. deep clay or snow - it may help to get the vehicle moving by allowing a certain amount of wheel spin. If the TCS switch is pressed, the reference speed at which traction control starts, is increased by 10 km/h.

65

EBS - Gen. 2

66

EBS - Gen. 2 Trailer Brake System (TBS)

At certain times - e.g. when changing a trailer, or making adjustments to the fifth wheel - it may be necessary to independently apply the trailer brakes. Providing that road speed is less than 4 km/h, pressing - and holding down - the switch, supplies air at 4 bar pressure via the trailer yellow line. When the switch is released, or if road speed is above 7 km/h, the air supply pressure is reduced to zero.

67

EBS - Gen. 2

68

EBS - Gen. 2

Differential lock function

The Diff. lock function is provided to make it easier to engage the differential lock, and to prevent damage to differential components. When the switch is pressed, the TCS system applies a combination of engine power reduction and braking, to synchronise the speeds of the driving wheels, at which point, the diff. lock will engage. Note: speed synchronisation will not occur if the Terrain TCS switch is pressed.

69

EBS - Gen. 2

9990131 - optional 9998603/2

9998699 - 62 pin

70

EBS - Gen. 2 Test equipment

The break-out box, template and harness shown above are required for the following EBS Gen. 2 checks:

Footbrake valve - course Task 2

- footbrake signal - footbrake pressure

- check list (C) - check list (C)

Harness extension 9990062 is also required. Modulator course Tasks 3 & 4

- modulator signal - modulator pressure

- check list (B)

Turn template 9998603 to the correct side by matching the plug and template colours. Note: Harness 9998603 - 7 plugs - can be used on Gen. 2 systems. Harness extension 9990062 is also required.

71

EBS - Gen. 2 X1 = EBA - BLACK X2 = EBB - YELLOW X3 = EBC - GREEN X4 = EBD - PURPLE

9998596/2 9998699

72

EBS - Gen. 2 Test equipment ECU course Task 5, check list - ECU

Harness 9998596/2, with 5 connectors, can be used for Gen. 2 and Gen. 3 systems. For Gen. 2 systems, the blue connector is not used. Earlier harness 9998596, with 4 connectors, can be used only for Gen. 2 systems. Harness extension 9990062 is also required. Break-out box 9998699 is used with harness 9998596/2 for Gen. 2 systems only. Note: The check list also refers to break-out box template 9990131, but some of the pin references do not match. Therefore, use the break-out box pin references

73

EBS - Gen. 2

74

EBS - Gen. 2 VCADS Pro - EBS Gen. 2 tests course Task 5a

50006-6 brake pads 50012-6 footbrake valve 50011-6 modulators 59364-2 ECU input/output signals 50013-6 TCS function shut off 50020-6 wheel speed sensor 59902-2 ABS control auxiliary brakes 50007-7 lining wear sensor calibration - front axle 50018-7 lining wear sensor calibration - rear axle

75

EBS - Gen. 2

9998544

9998534

ABS

ABS

1

2

ABS

3

76

EBS - Gen. 2 Truck/trailer ABS - warning lights and symbols

1 - truck ABS fault 2 - trailer ABS fault 3 - trailer without ABS connected Note: On trucks pre. version 2, trailer connection is sensed via the brake light connection - main suzie (77) pin 4. If current is sensed, via trailer relay (3023), a trailer is connected. On version 2 trucks, trailer connection is detected via the Light Control Module (LCM).

ABS course Task 6,

Harness 9998534 is used to check the trailer modulator on Gen. 2 trucks. Harness 9998544 is used to check the ABS trailer info. relay on pre-98 trucks.

77

EBS - Gen. 2 VCADS Pro - ABS

59305-6 solenoid control valves 59306-6 ECU 59302-6 wheel speed sensor 59303-6 toothed wheel

78

Electronic Braking System - Generation 3 79

EBS - Gen. 3 1

1

1

1

1

2

2

2

2

2

3

3

3

3

3

4

4

6x2 Tag

6x2 Pusher

6x4

8x2

Gen. 3 Axle configurations

8x4

80

EBS - Gen. 3

Axle configuration Gen. 3

Service information in IMPACT refers to the axles, and to components attached to the axles. The references are different from those used for Gen.2. They are simply numbered from 1 to 4, front to rear.

81

82

EBS - Gen. 3 EBS Gen. 3 introduction Main differences between Gen. 2 and Gen. 3

EBS Generation 3 was introduced late 2003. - modulators - ECU plugs - ABS valves added (certain axle configurations) - axle configurations - wake-up function - hill start aid - automatic diff. lock - new test equipment

Main software changes:

- emergency brake assistance (EBA) - drag torque control

83

Function

Truck variant Axle config. Standard FM/FH package EBS-STD

Electronic Stability

Tractors only

Program - ESP

Comfort package EBS-MED

4x2,6x2,6x4

ESP package EBS-HIG X

with air susp.

Hill start aid

All

All

X

X

Auto. diff. lock

All

Single drive

X

X

4x2,6x2 Lining wear trend anal.

All

All

X

X

Drag torque control

I-shift

All

X

X

Brake assist

All

All

X

X

Wheel brake monitor

All

All

X

X

EBS status recorder

All

All

X

X

84

Function

Truck variant Axle config. Standard FM/FH package EBS-STD

Comfort package EBS-MED

ESP package EBS-HIG

Anti Lock Brakes

All

All

X

X

X

Diagnosis via J1587

All

All

X

X

X

Traction Control

All

All

X

X

X

External Brake Demand

All

All

X

X

X

Differential lock

All

All

X

X

X

Brake Blending

All with

All

X

X

X

stalk control Lining Wear Sensing

All

All

X

X

X

Lining Wear Control

All

All

X

X

X

Brake temperature warning

All

All

X

X

X

85

EBS - Gen. 3

Software - 3 levels

The chart on the previous pages shows the features available with the three software levels - Standard, Medium and High.

Electronic Stability Program - ESP

ESP is aimed at helping to stabilise the vehicle if it reaches an unsafe situation - e.g. skidding, over/understeer, too fast into a curve, possible risk of vehicle over-turning. The system uses two additional sensors: - steering angle sensor on the steering column. This sensors detects the angle, direction and rate of steering wheel movement. - yaw rate sensor, which senses vehicle rotation and lateral acceleration. In response to signals from these sensors, ESP attempts to stabilise the vehicle by applying a combination of engine power reduction, and braking of certain wheels depending on the forces detected.

86

EBS - Gen. 3 Electronic Stability Program - ESP

Large steering wheel movements at high speed, a load with high or unstable centre of gravity, can bring the vehicle to the point of over-turn. The first attempted correction is reduction of engine power to reduce the lateral force. ESP then attempts to detect if one or more tyres is losing contact with the road. ESP detects this by lightly applying the brakes on one of the inner wheels. If light braking results in sudden deceleration of the wheel, this is interpreted as loss of road contact, and all brakes are applied. Note: This function does not apply if the trailer is not fitted with EBS. ESP does not work if there is an EBS fault.

87

EBS - Gen. 3

88

EBS - Gen. 3 Hill Start Aid

Hill start aid helps the driver to move off from a standstill on a hill. When the switch is pressed brake release is delayed, giving the driver more time to operate the throttle and clutch. Manual gearbox - brake pressure is maintained until the clutch is released, or until a certain engine load is detected. Automatic gearbox - brake pressure is maintained for a short time after the brake pedal is released, or until a certain engine load is detected.

89

EBS - Gen. 3 O = no diff. lock 1 = auto. diff. lock 2 = manual diff. lock

90

EBS - Gen. 3 Automatic diff. lock

This function is available only on trucks with one drive axle. The diff. lock is automatically engaged if the drive wheels begin to rotate at different speeds. EBS first synchronises the wheel speeds. The road speed must be less than 15km/h

91

EBS - Gen. 3

CHECK BRAKES Status Recorder 92

EBS - Gen. 3

Status recorder

The status recorder records the number of times a function has been applied - ABS, TCS, EBA, ESP, Temp. alert. Learning parameters must be reset to erase the fault codes.

Emergency Brake Assist (EBA)

If the brake pedal is pressed rapidly, this is interpreted as an emergency brake situation. The EBS ECU pressure signals to the modulator ECU are modified to provide increased brake pressure, so maximum braking power is attained more quickly.

Drag torque control

If the EBS system senses that the drive wheel speed is being retarded too much by the engine brake or retarder, the EBS ECU sends a signal to the engine brake or retarder to reduce retardation.

93

EBS - Gen. 3 4 3 1 2

5V SM2 AGNI SM1

6 11 12

21 22 94

EBS - Gen. 3

Wake-up signal

The EBS ECU receives a constant supply from the battery. Whenever the footbrake is pressed - even if the startkey is at off position - a signal is sent from terminal (6) to the EBS ECU, and the complete EBS system is switched on. This ensures that EBS will not go into back-up mode if other systems fail. Note: Wake-up does not work if the battery master switch is off. 5V. Controlled voltage supply to potentiometers SM2. Pot. output signal - 4.5v - 0.5V AGNI. Common earth SM1. Pot. output signal - 0.5V - 4.5V 6. Wake-up signal 11. Front circuit inlet - 8.5 bar 12. Rear circuit inlet - 8.5 bar 21. To front circuit 22. To rear circuit

95

EBS - Gen. 3

Brake temperature warning

Brake Blending - BBF

Brake lining temperature is estimated by the EBS system. If any wheel brake begins to overheat a warning light is lit. Overheat also causes brake ʻfadeʼ when the braking effect deteriorates, so the brake pedal must be pressed harder.

BBF is fitted only to vehicles with a retarder control stalk - stalk at ʻAutomaticʼ position. BBF automatically ʻblendsʼ braking power provided by the wheel brakes, and power provided by auxiliary brake systems - i.e. engine brake (VEB) and/or retarder. Because the reaction from auxiliary brake systems is slower than that from wheel brakes, the wheel brakes are always applied first. The ratio of braking power between tractor and trailer is not affected. 96

EBS - Gen. 3

Wheel brake monitoring

! Load sensing

The EBS system constantly monitors the efficiency of all wheel brakes. If the braking efficiency on any wheel brake is less than that at other wheels - e.g. due to grease on the linings, lining glazing or sticking calliper - a warning light is lit. Unlike Gen. 2 where load is sensed only by measuring the pressure in the rear air bags, with Gen. 3, load is also sensed by measuring the acceleration achieved for a given throttle opening, and deceleration achieved for a given brake pressure, After two or three gear shifts and brake applications, the effect of the load has been calculated, and brake pressure is adjusted accordingly. Following a load change, and before the load effect has been recalculated, the first brake application may feel different 97

EBS - Gen. 3 External Brake Demand - EBD

EBD is a demand, via the data link, from another ECU to apply or release the brakes. Examples are: - trailer - radar - driver falling asleep detection

98

EBS - Gen. 3

Brake force distribution - slip control

To ensure maximum retardation and stability at all times, the EBS system distributes braking force between front and rear tractor axles, and between tractor and trailer.

Distribution tractor front/rear

During light braking, the tractor front and rear axles receive approximately equal braking force, so lining wear is even. When more retardation is required, optimum brake force distribution is achieved by ʻslip-controlʼ, whereby braking force is distributed so that the front and rear wheel rotation speed is equalised. If the speed sensors detect that rotation speed is not equal, braking force to the faster wheels is increased, and braking force to the slower wheels is reduced. In relation to the tractor brake pressure, pressure to the trailer can be adjusted + 1.5 bar to - 0.5 bar. If the trailer has EBS, all tractor and trailer wheels are braked using slip-control.

Distribution tractor /trailer

99

EBS - Gen. 3

X4 - EBD - Green X3 - EBC - Purple X2 - EBB - Grey X1 - EBA - Black 100

EBS - Gen. 3 EBS ECU

The Gen. 3 ECU still has four plugs, but the colours are different from Gen. 2.

101

EBS - Gen. 3

1

2

3 102

EBS - Gen. 3 Modulators

The new modulators, used with Gen. 3 systems, are smaller then those used with Gen. 2 systems. The principle of operation is the same. 1. Single channel modulator 2. Twin channel modulator 3. Trailer modulator

103

EBS - Gen. 3

10 9

1

2

6b 6 6a 4 5 7a 7

8 7b

10 3

104

EBS - Gen. 3 ABS control valve

Normal braking

On 4 x 2, 6 x 2 and 6 x 4 trucks, with single front axle, a single channel modulator, with two ABS, valves is fitted. The ABS valves are controlled by the modulator. 1. Air supply 2. Air delivery 3. Exhaust 4. Inlet solenoid 5. Exhaust solenoid 6. Inlet valve 6a. Exhaust seal on inlet valve 6b. Inlet seal on inlet valve

7. Exhaust valve 7a. Inlet seal on exhaust valve 7b. Exhaust seal on exhaust valve 8. Diaphragm - exhaust 9. Diaphragm - inlet 10. Springs

During normal braking: - solenoid (4) is not energised, so inlet valve (6) is open. - solenoid (5) is not energised, so exhaust valve (7) is closed. Air can flow freely back and forth through inlet (1) and delivery (2).

105

EBS - Gen. 3

10 9

1 6b 6 6a 4

2

5 7a 7

8

7b

10 3

106

EBS - Gen. 3 ABS control valve Lock-up detected

If a tyre begins to lose grip, on loose or icy surfaces, braking will cause that wheel to lose speed at a faster rate than other wheels. Without correction the wheel will soon lock-up, and cause loss of control. The speed difference is detected by the wheel speed sensor, so an ECU signal results in: - solenoid (4) is energised, so inlet valve (6) is closed. - solenoid (5) is energised, so exhaust valve (7) is open. The pressure to the brake chamber for the locking wheel is reduced, and wheel lock-up is avoided.

107

EBS - Gen. 3

10 9

1

2

6b 6 6a 4 5 7a 7

8 7b

10 3

108

EBS - Gen. 3 ABS control valve Wheel speed equalised

When the sensors detect that all wheels are rotating at the same speed, the valve switches to pressure maintain mode: - solenoid (4) is energised, so inlet valve (6) is closed. - solenoid (5) is not energised, so exhaust valve (7) is closed. This ensures that the braking pressure is maintained in the chamber, at a level which gives the maximum possible retardation, whilst avoiding wheel lock-up. Any further pressure applied to the footbrake pedal, has no effect on the air pressure in the chamber.

109

EBS - Gen. 3 Multi-channel systems

Depending on the number and configuration of axles, EBS systems have 3, 4 or 5 channels. The number of channels refers to the total number of modulator channels - excluding the trailer modulator:

3 channel

1 x single channel modulator + 1 x 2 channel modulator.

4 channel

2 x single channel modulator + 1 x 2 channel modulator.

5 channel

3 x single channel modulator + 1 x 2 channel modulator

110

111

EBS - Gen. 3 10

36

10. Footbrake valve 33. Brake chamber 36. ABS valves 37. Single channel modulator 37a. Twin channel modulator 37b. Trailer modulator

36

CAN J1936 CAN J1939

ECU 37 E

R

37a AG

37b

AG. To auto. gearbox E. To engine ECU. EBS ECU R. To retarder T. To trailer SS. Wheel speed sensor WS. Wear sensor J1708/1587. Slow data link (orange) J1939. Fast data link (green) J1936 -

CANJ1708/1587

112

EBS - Gen. 3 WS

SS

33

36

10

37

WS

SS

33

33 ECU

36

SS

WS

37a T

33

SS

WS

37b

Note:

Three Channel System - 4 x 2

2 ABS valves for front axle Front single modulator controls - axle 1, LH and RH Rear 2 channel modulator controls - axle 2 LH and RH

113

EBS - Gen. 3 10

36


36

CAN J1936 CAN J1939

ECU 37 E

R

37a AG

37b

AG. To auto. gearbox E. To engine ECU. EBS ECU R. Retarder T. To trailer SS. Wheel speed sensor WS. Wear sensor J1708/1587. Slow data link (orange) J1939. Fast data link (green) J1936 -

CANJ1708/1587

114

EBS - Gen. 3 WS

SS

10

36

33

33 37

WS

SS

Note:

WS

ECU

33 36

SS

WS

37a

T

33

SS

WS

SS

WS

37b

Three Channel System - 6 x 4

2 ABS valves for front axle Front single modulator controls - axle 1, LH and RH Rear 2 channel modulator controls - axle 2 and 3, LH - axle 2 and 3, RH

115

EBS - Gen. 3

10

36


36

CAN J1936

37b

37

ECU

CAN J1939

37

E

R

AG

37a CANJ1708/1587

AG. To auto. gearbox E. To engine ECU. EBS ECU R. To retarder T. To trailer SS. Wheel speed sensor WS. Wear sensor J1708/1587. Slow data link (orange) J1939. Fast data link (green) J1936.

116

EBS - Gen. 3 WS

36 SS

10 33

33 37

WS

SS

Note:

36

37

ECU

33

WS SS 33

T

SS

WS

37a

33

SS

33

WS

SS

WS

37b

Four Channel System - 6 x 2 pusher

2 ABS valves for front axle Front single modulator controls - axle 1, LH and RH Rear 2 channel modulator controls - axle 3, LH and RH Rear single channel modulator controls - axle 2, LH and RH

117

EBS - Gen. 3


10 CAN J1936

37b

37

ECU

CAN J1939

37 E

R

AG

37a CANJ1708/1587


118

EBS - Gen. 3 WS

SS

33

10 33

33

37

SS

33

WS

ECU

37 WS

SS

SS

WS

37a

T

33

33

33

SS

WS

33

SS

WS

37b Note:

Four Channel System - 8 x 4

No ABS valves Front single modulators control - axle 1 and 2, LH - axle 1 and 2, RH. Rear 2 channel modulator controls - axle 3 and 4, LH - axle 3 and 4, RH. An 8 x 4 is the front of an 8 x 2, and the rear of a 6 x4

119

EBS - Gen. 3

10

37b CAN J1936

ECU 37

37 CAN J1939

E


R

AG

37

37a CANJ1708/1587


120

EBS - Gen. 3 WS

SS

33

10

37

WS

Note:

33

SS

ECU T

33

33

SS

33

SS

WS

WS

37

37a

37 SS

33

33

33

SS

WS

WS

37b

Five Channel System - 8 x 2

No ABS valves Front single modulators control - axle 1 and 2, LH - axle 1 and 2, RH Rear single modulator controls - axle 4 LH and RH Rear 2 channel modulator controls - axle 3 LH and RH

121

EBS - Gen. 3

A 9998699 - 62 pin 9990180

122

EBS - Gen. 3 Footbrake valve test

For the footbrake valve test, use harness 9990180, breakout box 9998699, and harness extension 9990062. Note: The large plug (A) is the correct plug to use when connecting to the footbrake valve.

123

EBS - Gen. 3

9990221

9990180 9998699 - 62 pin

124

EBS - Gen. 3 Modulator test

For the modulator test, use harness 9990180, breakout box 9998699, break-out box template 9990221 and harness extension 9990062. Note: Lead No. 2 - 4 pin is used only for ESP.

125

EBS - Gen. 3

9998567 126

EBS - Gen. 3 Trailer modulator test

For the trailer modulator test, use harness 9998567.

127

EBS - Gen. 3

9998539

9998539 X1 BLACK

9998596/2

X2

GREY

X4

PURPLE

X3

GREEN

9998596/2

9998699 - 62 pin 128

EBS - Gen. 3 ECU test

Refer to the check list - ʻEBS Gen. 3 ECUʼ. For the ECU test, use harness 9998596/2 (Gen. 2 harness). Tie-up the blue plug - it is used only for ESP. Because Gen. 3 ECU connector X2 is different from Gen. 2, new harness 9998539 is also required. Break-out box 9998699 is used without template 9990221. Harness extension 9990062 will be required.

129

EBS - Gen. 3 Op. Ref. No.

Reset test

Function

59392-2 59393-2 59394-2

1 2a 2b

59395-2 59396-2

3 4

Brake pedal activation Wheel speed Wheel speed (changed tyre circumference*) Manoeuvrability Control unit reset

* If new wheels or tyres are fitted, resulting in a different tyre circumference, this parameter must be reset.

130

EBS - Gen. 3 Resetting learning parameters

In addition to recording fault codes, the EBS ECU also records other information - e.g. braking characteristics, number of activations of components, change of wheel/tyre diameter. Such information is referred to as ʻlearning parametersʼ. Using the instrument panel display control stalk - or VCADS Pro - most fault codes can easily be deleted without going through any other procedure. However, when certain fault codes have been recorded a number of times, any related learning parameter must be reset before the fault code can be deleted. The table above gives the operation numbers for the five reset tests. For reset procedure, refer to these numbers in IMPACT.

131

132

133

134

EBS Training

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