Mando ABS System
October 12, 2022 | Author: Anonymous | Category: N/A
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Description
SAMAND (XU7JPL3)
Service Manual
ABS MANDO (MGH - 25)
Chapter:
Product: SAMAND XU7JPL3
Section:
ABS MANDO MGHMGH- 25
SAMAND Service Manual Foreword:
This Service Manual contains descriptions of the following categories for the Samand: ABS MANDO (MGH - 25)
This manual should be used as service manual and s workbook for training instructors and technicians. We reserve the right to introduce change without prior notice.
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Contents No.
Section
Page
1
Advantages of ABS system............................................................................ system......................................................... ...................
no. 3
2
ABS system Structure..................................................................................... Structure.................................................. ...................................
4
3
ABS system Components............................................................................... Components................................................ ...............................
5
4
ABS system Operating Procedure ................................................................ ................................ ................................
9
5
ABS Trouble Diagnosis ........................................................................ .................................... .............................................. ..........
11
6
ABS Trouble List........................................................................ List..................................... ........................................................ .....................
12
7
ABS (HECU) Replacement Procedure........................................................... Procedure................................................... ........
22
8
Filling and Bleeding System After Installing A/S Type Modulator ..
26
9
Comparing Active and Passive Sensors....................................................... Sensors................................................. ......
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10 11
ABS Schematic Diagram................................................... ABS ECU Schematic Diagram........................................................................ Diagram.................................................... ....................
28 29
12
ABS ECU Block Diagram .................................................................... ................................ ............................................... ...........
30
13
Schematic Diagram of ECU Connector Terminals.......................................
31
14
Clarifying Some Customer Complains.......................................................... Complains................................................. .........
34
15
General Information About ABS.................................................................... ABS........................................... .........................
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1
Mando ABS Assembly
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1 - Advantages of ABS system. - improved vehicle stability. - better steering control - reduced braking distance
Diagrammatic Illustration of ABS System Advantages
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2 - ABS System Structure
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3 - ABS System Components ECU (Electronic Control Unit): Speed fourthe wheels aretransmitted evaluated by ECUofbythe using signals by wheel speed sensor and by considering wheel slip levels it sends action commands to the solenoid valves and the HECU electromotor and thus mani ma ni ul ulat ates es the the br brak akin in re ress ssur ure. e.
Wheel speed sensor: The wheel speed sensor obtains data from the toothed wheel called exciter present on wheel axle and transmits it to the ECU which evaluates the wheel speed.
Electromotor: When the ABS becomes active, the ECU gives action command to ABS electromotor to pump brake fluid depending on the changes in wheel speed.
HU (Hydraulic Unit): The primary circuit of the HU is used for normal braking operations and its secondary circuit is used for ABS action. The hydraulic unit is composed of a group of components and controls the braking pressure applied to each wheel. The ECU evaluates the wheel slippage condition from the incoming sensor signals and when the ABS activation becomes necessary it analyses the situation and immediately activates the solenoids and the pump according to the instant programs it prepares and manipulates the braking pressure on each wheel as needed by the situation.
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3.1 - Wheel speed sensor
- when the toothed wheel on the wheel axle starts rotating the speed sensor's magnetic field changes and an electromotive force is created. - the wheel speed is evaluated on the basis of the fluctuating frequencies and volt vo lta a e cha han n es wh whic ich h are are ro or orti tio ona nall to wh whee eell s ee eed. d.
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3.2 - HCU (Hydraulic Control Unit) Unit) 3.2.1 - NO Solenoid valve (normally open): When is into no electric current this solenoid remains open and the brake fluid is allowedthere to flow the calipers. When there is electric current, this solenoid valve closes and brake fluid route to calipers is cut off.
3.2.2 - NC Solenoid valve (normally closed): When there is no electric current this solenoid valve remains closed and the brake fluid path between wheel caliper and LPA is cut off. When there is electric current this solenoid valve opens and the path between wheel caliper and LPA is established.
3.2.3 - LPA (Low Pressure Accumulator): When the braking pressure is more than necessary and the ABS decides to reduce braking pressure in the wheels, the NC solenoid valve opens and the extra brake fluid passes into the LPA and from there it is transferred to the t he reservoir.
3.2.4 - Pump: The extra brake fluid which is passed into the accumulator is transferred to the reservoir by the pump.
3.2.5 - Electromotor: It is an electromotor which makes the pump work.
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3.3 - HECU HECU
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4 – System Function 4.1 - ABS Range of Action
Slip rate:
λ = =
vehicle speed - wheel speed * 100 Vehicle speed
Wheel locked situation
λ =
100 %
Brakes are not applied
9
λ = =
0%
4.2 - EBD (Electronic Braking-pressure Distribution)
With EBD
With P valve
What does EBD do? Due to the electronic braking-pressure distribution (EBD), the front and rear wheels are prevented from slipping and getting locked due to proper coordination of braking force. In other words EBD is a substitute of the P-valve which is used in vehicles not having ABS system. Vehicles always have more braking in the front section so the rear section gets locked before the front section and causes the vehicle to deflect from its path. The level of braking force to be applied to rear wheels depends on the load that the vehicle carries and the EBD balances this force.
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5 - ABS system Trouble Diagnosis. Diagnosis. 5.1 - Trouble Diagnosis Chart:
Warning lamps (W/L) EBD
Trouble symptoms
Trouble cause
ABS locking of wheel and Incomplete
Fault in brake piping assembly
braking OFF
OFF
ABS & EBD working abnormally
Brake fluid leakage Trapped air in brake hydraulic
Reduced ABS action
circuit
OFF
ON
ABS fails to act
Electromotor defective
ON
ON
ABS/EBD fail to act
ECU current defective
ON
ON
ABS/EBD fail to act
OFF
ON
ABS fails to act
ON
ON
ABS/EBD fail to act
ON
ON
ABS/EBD fail to act
ECU defective
*
ON
ABS fails to act and in some
Defective connection or
cases ABS/EBD fail to act
continuity break in sensor.
*
Unit
ON
Vehicle wiring harness Electromotor
Solenoid valve current defective Electromotor current defective Defect in ECU board connections
- sensor rotor defective
- ABS malfunctioning
- improper gap clearance
- ABS/EBD fail to act
between sensor and rotor
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ECU
Wheel speed sensor
5.2 - List of all ABS system faults.
1. Open circuit or short circuit in FL sensor 2. Defective FL sensor exciter 3. Improper FL sensor-exciter gap clearance 4. Open or short circuit in FR sensor 5. Defective FR sensor exciter or interference error 6. Improper FR sensor-exciter gap clearance 7. High battery voltage (above 16 V) 8. Low battery voltage (below 9.4 V) 9. Defective ECU circuit or solenoid valve winding 10. Open or short circuit in RL sensor 11. Defective RL sensor exciter or interference error 12. Improper RL sensor gap clearance 13. Open or short circuit in RR sensor 14. Defective RR sensor exciter or interference error 15. Improper RR sensor-exciter gap clearance 16. Defective electromotor or blown up electromotor fuse 17. Defective solenoid valves
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5.3 - Method of Diagnosing Faults. 5.3.1 - Open circuit or short circuit in wheel sensor: Take out wiring harness and sensor and make a general check up and fit terminals back on the connector pins.
Is the problem solved?
Fit connector pin terminals in proper position and harness its wiring in a suitable manner.
Check wire continuity between connector A and connector B which connects ECU to sensor.
Find out the open circuit or short circuit and repair it or replace wire.
Is there continuity in the wire?
Replace sensor.
Does the fault exist even after replacing sensor?
End Note 1: Connection of the connecters.
Replace HECU.
Note 2: Terminal numbersChannel
Pin no.
FL
1/2
FR
19/20
RL
5/6
RR
22/23
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5.3.2 - Defective sensor and exciter: Remove car wheel on defective sensor side and check sensor and exciter wheel condition . Measure gap clearance between sensor and exciter
Is it between 0.5 to 1.5 mm?
No Adjust gap clearance. (between 0.5 to 1.5 mm; best being 0.7 mm.)
Yes Check for exciter teeth condition and any debris sticking on teeth.
Yes Are the teeth damaged?
Replace exciter.
No Yes Is there debris on exciter teeth?
Remove debris.
No Replace sensor.
No Does the fault exist even after replacing sensor?
End
Yes Replace HECU.
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Note 1: If debris is sticking to exciter teeth, signal transmissions will be irregular. Note 2: Air-gap (gap clearance) is the gap between sensor and exciter teeth.
5.3.3 - Improper sensor gap clearance: Remove car wheel on defective sensor side and check sensor and exciter wheel condition.
Measure gap clearance between sensor and exciter wheel teeth.
No
Is the gap between 0.5 to 1.5 mm?
Adjust gap clearance (between 0.5 to 1.5 mm)
Yes Detach connectors B and C and check wire continuity between connectors A and B of wiring harness.
No Does the wire have continuity?
Find out the break in wire or the short circuit and repair or replace wire.
Yes Replace sensor.
No
Does the fault persist even after replacing sensor?
End
Yes Replace HECU.
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Note 1: Connection of the connectors-
Note 2: Terminal numbers-
Channel
Pin no.
FL
1/2
FR
19/20
RL
5/6
RR
22/23
Note 3: Air-gap (gap clearance) is the gap between sensor and exciter teeth.
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5.3.4 - Battery voltage problem: Measure electrical resistance between pin 4(+) of wiring harness
Detach wiring harness and start engine and measure voltage between pin 4(+) and pin 8(-) and also pin 4(+) and pin 24(-).
connector and positive terminal of battery. ∗
No Is the voltage within 9.4 to 17 V?
Measure voltage between +ve and -ve terminals of battery. No
Is voltage below 9.4 V?
Yes Check for faults and connect wiring harness terminals to pins 4, 8 and 24 of connector.
Is the problem solved?
No
Check wiring harness and replace if necessary.
Is it below one ohm?
Yes Check grounding of pin 8(-) of connector and wire terminal 24(-) of the wiring harness.
Yes Check and replace battery.
Adjust connector pins and connect them properly.
Yes
Is the problem solved?
Yes
No
Replace HECU.
Set ground contact properly. Start engine and measure voltage between pin 4(+) and pin 8(-) and also between pin 4(+) and pin 24(-).
Start checking again from stage ∗
Is it above 17 V?
No
Replace alternator.
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5.3.5 - Defective solenoid valve relay or fuse: fuse: ∗
Detach wiring harness and check continuityand between pin 25 of connector ground. Check continuity between pin 25 of wiring harness and terminal of fuse box.
No
Does it have continuity?
Does it have continuity?
Yes
Check wire of pin 25 and replace.
Check ABS solenoid valve fuse in fuse box.
Replace solenoid valve fuse.
No Is fuse intact?
Yes Check and see if pin 25 of wiring harness is fitted ro erl .
Set connector pin in correct position and fit connector properly.
No Is the problem solved?
No Put HECU to work (solenoid valve relay and electromotor).
No
Yes Start checking again from stage ∗
Is it possible to make it work?
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Replace HECU.
5.3.6 - Defective electromotor or electromotor fuse: fuse: ∗
Detach wiring harness and check continuity between pin 9 and ground.
Check continuity between pin 9 of wiring harness and fuse box terminal.
Yes Does it have continuity?
Does it have continuity?
Yes
No Check wire of connector pin 9 and replace if necessary.
Check wire of connector pin 9 and replace if necessary.
Check ABS solenoid fuse condition in the fuse box.
No
Replace solenoid fuse.
Is fuse intact?
Yes Check to see whether pin 9 of wiring harness is properly connected.
No
Is the problem solved?
Set connector pin in correct position and fit connector properly.
Yes Put HECU to work (solenoid valve relay and electromotor).
Yes Starting check again from stage ∗
No
Is it possible to make it work?
19
Replace HECU
5.3.7 - Defective solenoid valve winding or ECU internal circuit:
Detach wiring harness and check electrical resistance between pin 8(-) of wiring harness and the ground, and also between pin 24(-) of wiring harness connector and ground.
No Is it below 10 ohms?
Yes
Replace HECU.
20
Check ground contact of pin 8(-) of the connector and ground contact of terminal 24() of wiring harness.
5.3.8 - Warning lamps turning on without reason:
Detach wiring harness and check continuity between pin 16 of connector and ABS module.
No Does it have continuity?
Yes
Check to see whether pin 16 of wiring harness connector is properly connected.
Start engine and connect pin 16 of wiring harness connector to ground.
No Does warning lamp turn on?
Check ABS module (relay) and replace.
Yes Battery +ve
Replace HECU
Note 1: ABS module connections-
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5.4 - ABS (HECU) replacement procedure procedure 1 - While engine is off, detach the 25 pin connector from HECU.
25 pin connector of ABS, MGH-25.
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2 - Disconnect brake pipes connected to HECU. To do this, use a 11mm spanner and open 6 nuts of size M10*1.0, by turning spanner in anti-clock wise direction.
* tightening torque for brake pipe nuts is 120 to 160 kgf.cm. * tightening torque for bracket bolt and nut is 190 to 260 k f.cm.
3 - Detach bracket by using a 12 mm spanner and removing the three bolts and nuts, by turning spanner in anti-clock wise direction.
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4 - After removing HECU from the vehicle along with the bracket, separate HECU from bracket by opening the three allen screws M6×1.0 by using a 5 mm allen wrench and by turning it in anti-clockwise direction.
5 - Use a 6 mm allen wrench to remove the six allen screws of HECU of A/S type by turning it in anti-clockwise anti-clockwise direction.
Note: Two types of modulators are used in this system1. The dry modulator which is used when vehicle is assembled in factory. 2. The wet modulator which is used in the after sales service (A/S) program. Since the use of dry modulator needs filling brake fluid and performing bleeding operation and this operation is problematic outside factory assembly line, hence for after sales services the wet modulator is used used which is already filled filled with brake fluid and it has has a different part no. from that of the dry modulator. When the wet modulator is used it does not need to pass the filling and bleeding tests under the DIAG device and as such the HECU can be easily replaced and its bleeding operation is same as the bleeding operation of the normal without ABS brake system.
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6 - To reinstall, attach bracket to an A/S type HECU by using the three allen screws of size M6×1.0 and tightening them in clockwise direction with a 5 mm allen wrench.
Tightening torque for the allen screws is 80 to 100 kgf.cm.
7 - Reinstalling procedure procedure even for the A/S type modulator is in reverse ord order er of removal.
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5.5 - Filling and bleeding procedure after installing A/S type modulator. modulator. 1 - After replacing the old modulator with a new A/S type modulator (wet type), start engine and by using DIAG device check for faults. - if faults are reported, eliminate the faults. - if the faults cannot be eliminated, then refer to fault diagnosing section given in this manual. manual. 2 - Press brake pedal and remove one of the bleeding nuts and then follow the procedure for expelling air from the system and then close the bleeding nut. Repeat this procedure for the other wheels too until all air is expelled from system. - see that the brake fluid in the reservoir always remains in the upper level. 3 - If air is still present in system or the brakes are not functioning well, repeat the procedure again from phase 2. - if even after ten times repeating of this procedure the problem is not solved then replace the modulator and start the procedure once again from stage 1.
5.6 - Bleeding and Filling Operation Tips. Tips.
If after executing the above procedures, still you feel that the pedal is depressing too much when the ABS is active, then do the following: 1 - Connect DIAG device and set it on bleeding mode. 2 - Press brake pedal until it gives up all pressure and then leave it off. 3 - Then immediately press pedal again and repeat this procedure until the bleeding mode is completed. - bleeding mode: Repeated bleeding operation by making engine to run for one minute and activating for two seconds and deactivating for two seconds the NC solenoid valves. - after the bleeding mode is completed, execute stages 2 and 3 of section 5.5.
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In Mando ABS system the active type of sensors have been used, a comparison of which is given in the following table.
Review of ECU Accommodation Passive sensor Power supply
N/R
Type Air gap
Inductive 0.8 - 1.2 mm Voltage/Variable Voltage/Varia ble amplitude (dependent on vehicle speed)
Active sensor Provided from battery via ECU Hall effect 0.5 - 1.5 mm Current/pulse (independentt of vehicle (independen speed)
I-V conversion
N/R
Required
Protection circuit Low speed output characteristics
N/R
Required
2 KPH Min
0.14 KPH Min
Output
Input/ output characteristics of sensor
Active sensors have a semi-conductor installed in a magnetic ring and act according to the hall effect and have a higher sensitivity compared to the passive sensors and also a longer action range, and the other advantages of active sensors is the weaker magnet they have which does not attract iron filings and so gives lesser trouble, when in fact the passive sensors due to their stronger magnet easily attract iron filings to the sensors and cause interference in performance. In this vehicle the front wheel sensors can be interchanged but the rear wheel sensors differ from each other and cannot be interchanged. interchanged. To differentiate the rear wheel sensors a red band is used for the right wheel sensor and a blue band is used for the left wheel sensor and their part no. also differ. Rear wheel sensors are connected by a connector to the wiring harness of the rear lamps and the front wheel sensors are directly connected to HECU and there is just one intermediate connecter on the route in the region below the driver's feet.
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Schematic Connections Diagram of ABS ECU Block
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Schematic Circuit Diagram of ABS ECU Block
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Schematic Diagram of ECU Connector Terminals
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Feature of ECU Input and Output Signals
Connector terminal Feature Trml.no. Designation
4
IGN+
8 24
GND1 GND2
7
DIAG
Description
Live from ignition switch
Ground
DIAG interface socket (K-line/Lline)
3
FR-OUT
Wheel speed output
18
BRAKE
Brake stop lamp input
16
ABS/EBD WLP
25
BAT 1
9
BAT 2
Remarks
ABS & EBD warning lamp exit Battery supply 1 (supplying solenoid valve)
Voltage upper limit: 16.5±0.5V
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