Chery A21 2005, Service Manual, Page: 111 / 475

CHERY A520 SERVICE MANUAL CHASSIS
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SECTION VIII ABS SYSTEM MAINTENANCE
Needed tools: Chery-specific diagnostic tester, 10#, 13# open end wrenches, ratchet wrench
and 10# sleeve
8.1 Precautions prior to maintenance
1) When the ignition switch is at the ignition position, you should not disassemble and
assemble the electric components and harness connectors of the system in order to
prevent the electronically controlled units (ECU) from being damaged. Before
disassembling and assembling, you should turn off the ignition switch.
2) You are not allowed to supply extremely high voltage to ECUs, otherwise the ECUs
shall be easily damaged.
3) Protect the ECUs from being impacted and knocked in order to avoid of damage.
4) High temperature environment is prone to damage ECUs; therefore, you should remove
the ECUs from the car when baking paint for the car. In addition, when welding the
system components or wire harness, you should also pull out the harness connectors
from ECUs.
5) Prevent oil stain from splashing onto ECUs, especially the terminal. Otherwise, it shall
lead to loose contact of terminal.
6) When the battery voltage is too low, the system cannot be operated. Therefore, you
should check the battery voltage, especially at the circumstance that you launch the
initial startup after stopping driving the car for a long time.
7) Prevent the wheel speed sensor and sensor gear ring from being polluted by oil stain or
other dirties. Otherwise, the wheel speed sensor shall generate inaccurate wheel speed
signal, which shall further impose influence on the accuracy of system control, and even
lead to system failure. Furthermore, you are prohibited to knock the rotation speed
sensor; otherwise, sensor-degaussing phenomenon may be prone to occur, which is
unfavorable for the normal operation of system.
8) When repairing the hydraulic system, you should firstly discharge the high-pressure
brake fluid of the energy accumulator completely in order to protect persons from being
hurt by the splash of high-pressure brake fluid. In the case of discharging the
high-pressure brake fluid of energy accumulator, you should firstly turn off the ignition
switch, and repeatedly step on and loosen the brake pedal until it becomes very hard.
Additionally, before the brake hydraulic system is well installed, you are not allowed to
turn on the ignition switch with a bid to stop the electrically-driven pump from
operating.
9) The brake system should use special pipeline, since brake system often has a very high
pressure. If general pipeline is utilized, it shall be easily damaged.
10) Because the wheel speed sensor, ECUs and brake pressure adjusting devices of the
antilock brake system (ABS) cannot be repaired, you should replace them completely if
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