Chery A15. Manual - part 86

Caution: This failure mode is available only when the system can communicate with

the diagnostic instrument (ABS ECU power supply normal) and there is no
DTC.

Check the open circuit of wires between

          Yes

  ECU and ABS warning lamp controller

                          Replace  harness

No                Abnormal

Check the ABS warning lamp controller

                      Replace

Normal

Replace the ABS ECU

ABS operation abnormal

       Possible Cause

[Description] This problem is related closely to

the driver and road conditions, and
thus it is difficult to diagnose this
failure. However, if there is no DTC
memory, the following checks may be
conducted.

*    Improper installation of
sensor
*    Sensor harness problem
*    Sensor damaged
*    Gear ring damaged
*    Sensor adhered with
foreign material
*    Wheel bearing damaged
*    ABS HCU (Hydraulic
Control Unit) damaged
*    ABS ECU (Electronic
Control Unit) damaged

P-37

Normal

Replace the ABS ECU

No

Install it properly

Yes

Abnormal                                                    Abnormal

Replace

Normal                                                          Normal

Abnormal

Replace

Abnormal

Normal

                                                                    Abnormal

Replace the ABS HCU

Repair or replace

Normal

Replace the connection

          Normal

No

Normal

Abnormal

  Repair the harness

                                                                                                                                or  connector

ABS ECU

Sensor is installed properly or not

Check the sensor output voltage

Use the diagnostic tester to

conduct the HCU diagnosis

Check all sensors

Check all sensor gear rings

Check wheel bearing clearance

Check ABS ECU socket and

intermediate connector

Failure reoccurs or not

Refer to “Repair Details

of Random Failure”

Remove the ABS ECU connector, and check

whether the resistances between the

following terminals of ABS ECU conform to

the standard values?

Standard resistance: 1.0-1.3 k

Measure the resistances, and, at the same

time, swing the sensor harness and connector.

MK20I/E

FL wheel: 1-2     RR wheel: 19-20

RL wheel: 5-6     FR wheel: 22-23

Abnormal

Abnormal

P-38

Abnormal

Normal

Too long brake pedal travel

        Possible Cause

[Description] Firstly take the visual inspection to

determine the outside leakage or
mechanical failure. Use the air bleeding
method to check the air in the system. And
use the diagnostic tester and hydraulic
testing to check the leakage of normally
closed valve (NC valve).

*    Brake fluid leakage
*    NC valve leakage
*    Air kept in the system
*    Serious brake disc
wear
*    Hand brake
adjustment improper

Abnormal

        Tighten the pipe joint according to the requirement

Normal

Abnormal

Replace the brake disc

Normal

Abnormal

Replace the hand brake adjusting equipment

Normal

                                Abnormal

Air bleeding again

 Normal

Abnormal

Replace HCU (Hydraulic Control Unit)

Forcefully step on the brake pedal

Possible Cause

[Description] Use the traditional method to check and control

the booster and brake pedal travel. The failure of NO

(Normally Open) valve can be checked using the

diagnostic tester’s hydraulic control unit function.

*    Booster failure

*    NO valve failure

Replace HCU (Hydraulic Control Unit)

Visually inspect the leakage of hydraulic

Check the wear condition of brake

Check hand brake adjusting

Air bleeding check

Use the diagnostic tester HCU to

diagnose the sealing of NC valve

Use the diagnostic tester’s HCU to

diagnose and check the NO valve

Use the traditional method available

for ABS vehicle to check the booster

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Abnormal

Yes

Normal

No

Abnormal

No

Replace

Yes

Yes

Without DTC output (fail to communicate with the diagnostic tester)

Possible Cause

[Description] If it is difficult to communicate with the

diagnostic tester, it is possible that the supply

circuit of ABS ECU or the diagnostic circuit is

open circuit.

*    The fuse broken

*    The diagnostic circuit

broken or the connection

uncoupled

*    ABS ECU damaged

*      Diagnostic tester failure

No

Repair the diagnostic socket or ABS harness

Replace the ABS ECU

The diagnostic tester communicates with the

MK20 ABS ECU on the other vehicles

Check ABS supply fuse

The diagnostic tester failure, and

conduct the check after repair

Display it on the screen of diagnostic tester or not

Remove ABS ECU’s connections, check the

connection of the ECU related terminals in

ABS harness (terminal 7 for MK20 I/E) with

the diagnostic socket (terminal 7 in the

diagnostic tester)

Check the supply,
earth, and
diagnostic wires
in the diagnostic
tester socket, and
their connection

Repair the diagnostic

tester socket or harness

P-40