ABS troubleshooting for common failures
There are mainly 5 kinds of failures of ABS system. 1. Poor connection of ground wire of ABS. 2.
ABS sensor failure. 3. Misassembly of brake pipeline. 4. Damage of sensor annual gear or too large
clearance. 5. Inside failure of ABS module. The indicators positions are as follows:
Airbag indicator lamp Brake failure indicator lamp ABS warning lamp
1. Poor connection of ground wire of ABS.
The resistance between ABS module ground wire and battery negative pole should be less than 2
ohm. If it is more than 5 ohm, brake indicator lamp and ABS warning lamp will light up at the same
time. The electrophoresis paint and finish coat has the function of insulation. Long time loose
connection will lead to the corrosion of stator. Refer to the following:
ABS ground wire fixing point Fixing point between battery negative wire and vehicle body
Ground point paint is thick and rusted Ground wire stator surface is rusted
ABS ground wire is on the bracket. The fixing point of ABS ground wire on the fuse case bracket.
Solution: After clean the corrosion dirt, get rid of the electrophoresis paint and finish coat on the
ground wire hole,（note，the scrapped paint area should be less than ground wire stator）, reinstall the
stator and the failure will be eliminated.
2. ABS Sensor failure
If it is the sensor problem, the ABS warning lamp will light up. Use X-431 test scanner to check
which wheel sensor has failure. If vehicle moves at low speed（5～10 km/h）, the sensor has no
signal or the signal is weak, you can detect according to the ABS wheels speed sensor values on the
scanner. Or connect the voltmeter to the two terminals of the sensor, choose alternating current, the
voltage will increase along with the increase of the wheel speed, the voltage should be more than
100 milli-voltage. So far the failure mainly comes from front wheel; there are mainly three kinds of
failures:
1. Sensor has dirt, ABS probe head got iron powder or dirt, signal output is weak.
The proper treatment: Use metal brush to get rid of the
iron powder on the ABS sensor, at the same time use high
pressure air to clean the installation part.
2. Sensor electric circuit is short circuit or open circuit. The main reason is: sensor wire is short,
when steering knuckle moves to left and right, up and down, the wire movement is limited, and
the wire core might be snapped. Also during the running of vehicle the ABS sensor wire might
be cut down. .
Resistance value of front wheel sensor is about 1.1 k ohm
Resistance value of front wheel sensor is about 1.7 k ohm
The point that the front sensor wire (2WD) easy to be damaged
The point that the front sensor wire (4WD) easy to be damaged
3. Sensor is damaged. The main reason is brake floor and breaking disk have too much clearance.
Some hard materials may break into and damage the sensor and annular gear. The next cause
may be the annular gear or bearing is broken which leads to the damage of sensor.
The alnico stacked pieces on the head part are
worn:
Chassis got impacted, installation position is
transformed can caused abrasion.
Solution: Reinstall, make sure the clearance
between the piece and annular gear is 0.5-1.1
mm°.
The alnico stacked pieces on the
head part are damaged: caused
by outside force or other foreign
materials
Plug is damaged:
Damaged by outside force.
Repair method: repair the plug.
3. Misassembly of brake pipeline.
There are totally 5 break oil pipelines, if they are installed wrongly the rear brake causes the vehicle
run in wrong direction, ABS warning lamp light up, turn off the ignition switch and then turn on,
press the brake pedal the warning lamp light on.
The following are the 5 oil pipelines:
1 2 3 4 5
1 Rear break pipeline of main pump, marked Letter “MS”
2 Rear break pipeline, marked Letter “REAR”
3 Left front brake oil pipeline, marked Letter “LF”
4 Front brake oil pipeline of main pump, marked Letter “MP”
5 Right front brake oil pipeline, marked Letter “RF”
Rear brake oil pipeline of main pump Front brake oil pipeline of main pump
4. Damage of sensor annual gear or too large clearance.
Annular gear lost tooth, worn or smashed. The clearance between sensor and annular gear exceeds
the standard, the standard clearance value is: 0.35-0.8mm. The annular gear is as follows:
The whole annular gear has no phenomenon of losing tooth, abrasion and fragmentation.
5. Inside failure of ABS module
Under normal condition, ABS module can not be repaired, please replace the whole module. Pay
attention that do not install the brake pipeline wrongly, and make sure the plug is connected well.
Keep the failure parts clean, or foreign material might break into module and cannot be repaired in
manufacture factory.
Replace ABS module assembly
