Slide đào tạo hệ thống phanh ABS trên xe khách

Learning Goals You Can…  Understand Characteristics of the Anti-Lock Brake System  State Control Logic  Understand how ABS Components are controlled, operated and checked  State inpu

Anti-Lock Brake System

(County Bus, HD65,72 Truck)

Learning Goals (You Can…)

 Understand Characteristics of the Anti-Lock Brake System

 State Control Logic

 Understand how ABS Components are controlled, operated and checked

 State input and output element of the system

 Read trouble codes with/without Hi-Scan Pro

 Troubleshoot

 Repair ABS

 Understand System Layout and Location

General

Exercise

What is the characteristics of the ABS?

Discuss your opinion in the group and make a note of the most important items

 Stability

 Steerability

 Shorter emergency brake distance

 Drastic reduction of vehicle accidents

 Tire protection by avoiding brake flats, thus longer tire service time

 Advertising effect, e.g for tourist coaches

ABS Control Cycle

ABS General

Question

ABS General

Maximum Brake Force Utilization

Brake force coefficient µB as function of brake slip 

Specification

ABS General

Wheel Speed Sensor

Minimum Output 120 mV (at 30~60 rpm)

Hydraulic Modulator

Operating Pressure 200 kg/ ㎠ (Max 250 kg/ ㎠ )

Resistance Inlet Valve : 24.66±0.5 Ω Outlet Valve : 18.30±0.5 Ω

Self Diagnosis ABS

System Layout

ABS General

Self Diagnosis Initiate Line

ECU

Warning Lamp

Valve Relay Self Diagnosis

EB

Exercise : Diagram of Input / Output

Please fill out input and output element on the block diagram

Hydraulic Modulator

* Disc Type

Resistance Air gap Minimum output

1,600 ± 10(%)Ω 0.65 ~ 0.01 mm

120 mV (at 2.75 Km/h)

Wheel Speed Sensor

Components Description

Wheel Speed Sensor

* Drum Type

Resistance Air Gap Minimum Output

1,600 ± 10(%)Ω 0.65 ± 0.01 mm

120 mV (at 2.75 Km/h)

Wheel Speed Sensor

Components Description

Wheel Speed Sensor

ABS Warning Lamp

NOTE :

ABS warning lamp should be turned-off when driving the vehicle

Conditions of warning lamp

Vacuum tank Vacuum

3-way connector

ABS modulator

LSP valve

Rear wheel cylinder

Weight Operating Pressure Operating Temp.

* Motor relay : Should be replaced with motor and valve relay assembly

* Valve relay : Could be replaced with valve relay only

Motor relay &

valve relay

< VT >

Valve Relay & Motor Relay

Components Description

.

.

.

.

.

.

.

.

.

.

Damper Chamber

Plunger Pump

ECU

Components Description

E.C.U Connector

Components Description

ABS Control

Open Close OFF

Solenoid Valve Pump Motor

N.O N.C

Normal Braking

P

N.O N.O N.C

Hold Mode

ABS Control

Close Close OFF

Solenoid Valve Pump Motor

N.O N.C

P

N.O N.O N.C

Dump Mode

ABS Control

Close Open ON

Solenoid Valve Pump Motor

N.O N.C

P

N.O N.O N.C

ABS Control

Open Close ON

Solenoid Valve Pump Motor

N.O N.C

Increase Mode

P

N.O N.O N.C

FR FL

86 85 30

VR

⑭

⑮

MR

Exhaust Brake Relay

The ABS continuously checks the electrical integrity of the system If

the failures was detected on the system, the warning lamp will be

illuminated to notify the its states, and at the same time the ABS will

be switched off and operated conventional brake only.

The maximum 3 kinds of fault codes could be shown continuously by

warning lamp even though the system has more than 4 kinds of

a) system faults  warning lamp “blink”

B) normal  warning lamp “on”

How to read Trouble Code

IG Switch turn on - off more than 20 times

Self diagnosis mode would be finished while the vehicle speed is

over 10 km/h

How to remove the memory

Finishing

Troubleshooting

Troubleshooting

Trouble Codes

Low Voltage(NO ABS) : 20V or Less

Low Voltage (ABS Event) : 18V or Less ○ 1 IG ON : V bat

IG OFF : 0 VHigh Voltage : 34.8 V or Higher ○

51

Valve relay terminal is stuck to OFF or

open or short circuit of 3 or more valves

○

35,37,5,33,54,26,53,25,6,34

IG ON : V Bat (except 37)

IG ON(37 only) : 0 >V bat >0V

IG OFF : 0 VValve relay terminal is stuck to ON

Symptom BWL Pin No Standard Value

38 BLS terminal voltage is (Voltage × 55%)≤BLS Voltage≤(Voltage×

75%) (Open circuit), No system shut off ○ 48

Brake ON : V batBrake OFF : < (V bat × 55%)V

11,1

2,13,

14 Sensor resistance is 15±5 kΩ or more ○

9,10,13,14,11,12,39,40

Sensor output : ≥ 350mVp-p(at 75 km/h approx.)

Vref = 40km/h, Vw = 40km/h

No sensor output ○

One or more sensor have noise ○

15 ABS is operated more than 60 seconds ○

63 Internal error of ABSCM ○ Replace ABSCM

Troubleshooting

Troubleshooting by Trouble Codes (at ABSCM)

Air Bleeding

Caution

• Do not expose ABS ECU to splash-water, mud, dust or mechanical stress such as drop down etc.

• Do not expose ABS ECU to splash-water, mud, dust or mechanical stress such as drop down etc.

• Do not touch the electrical connectors with fingers or parts other than the wiring harness plugs

• Never weld on a vehicle while ECUs are connected

• Never start the Engine other than the own battery as long as ECUs are connected

• Never run the Engine (alternator) without a securely connected battery

• Never run the Engine (alternator) without a securely connected battery

• Never open an ECU nor try to repair it

Exercise : Service Advices

If you have vehicles with ABS ECU, how you handle it?

Discuss your service points in the group and make a note of the most important items

Case Study

Case Study

Case 1.

Symptom

ABS is activated when brake is applied with laden passengers

Vehicle : County Bus

Checked Item

Diagnosis by means of scanner (Hi-Scan)  No trouble code

Hub front wheel side is normal