According to the owner, the car turn on the left and turn the brake pedal, ABS fault light is lit; and turn right to turn the light brake pedal, ABS fault light does not shine, everything is normal.
    Then, on the bus, turn right and turn right and turn the brake pedal, ABS fault light does not shine. everything is normal. Turn left and turn the pedal, and after a few seconds, the ABS fault light is on. At this time, found a new problem. Turn the lights on the left and right, after the brake pedal, not only ABS fault light. Moreover, the flashing frequency of the turn signal also increased, that is, turn the lights flash quickly. According to experience, the turnlight flicker frequency is improved because one side of the turn signal has a light bulb that does not light up. Will appear above to now. To this end, immediately check the left front and rear turn signal, left front turn signal normal. And the left rear turn signal is normal when the brake pedal is not pedaled. Left rear turn signal is not bright, and become a left rear brake light one light off a flashing. According to this phenomenon. Judgment may be due to the left rear taillight wire break or poor contact. Check the left rear taillight and find the common ground wire plug really bad contact. Will be dealt with after the wire plug. Steering lights, brake lights are normal. At this time, and then check the ABS fault light is not bright. It can be concluded that the ABS system does not exist. But because the left rear taillight common grounding cable plug failure, which led to ABS system is not normal.
    Why is the above phenomenon? Analysis is as follows: due to the common ground wire plug bad contact. There is a certain resistance, a separate turn to turn the lights or brake lights, because a light bulb current is not. The voltage drop across the common ground wire plug contact resistance is not large and most of the voltage is applied to one of the turn lights or brake lights. The power of the lamp will not be greatly affected, so, alone turn the lights or brake lights, the basic normal, the fault will not be exposed. When the lights and brake lights are turned on at the same time. The current on the common grounding wire plug is increased. The contact resistance is constant, according to Ohm's law. The voltage drop u is equal to the current I multiplied by the resistance R, that is to say. In the case of constant voltage and resistance. The greater the current, the greater the voltage drop across the contact resistance. At this time, the current of the two bulbs at the same time through the poor contact with the common grounding wire plug, most of the voltage drop in the common grounding wire plug contact resistance. And the two bulbs on the share of the voltage is only a small part, not enough to make the two bulbs glow. Or even light is also very dark, in a well-lit environment, they can not see the light.
    In the above case, since the left rear turn signal is not lit, only the left front turn lamp is turned on, so that the flash frequency of the turn signal is increased.
    So, why the left rear brake light and why a light to flash it? This is because: although the steering switch is open. But when the flasher contacts are disconnected. Equivalent to a separate power to the brake light. This time. Only a brake light a light bulb, so the brake light is on. When the flasher contacts are closed, the turn signal and the brake light are energized at the same time, and most of the voltage is lowered on the contact resistance of the common grounding wire plug. Turn the lights and brake lights to obtain the voltage is very small, no light, it is equivalent to the turn signal and brake light does not shine. When the contacts of the flash are disconnected again. Leaving only a light bulb on the brake light. The current on the common wire plug is halved, the voltage drop is very small, the brake light is on again. In the case of failure of the cable. The brake light is turned off by the flasher. The flasher contacts are closed. Turn lights and brake lights are power, both lights are not bright. The flasher contacts are disconnected and only the brake lights are energized. Brake light on the light, this is the brake light a light off the reasons.
    Through the above analysis. Why do we light on the ABS failure to come to the conclusion: This is because the brake pedal down, the brake switch is closed, the voltage sent into two. All the way to the brake light, another way to the ABS control unit sent a brake voltage signal to inform the ABS control unit is now in the braking state, so that ABS function to play. Due to the above described turn signal and brake light circuit failure. So that the brake light flashes one by one. By its influence, the ABS control unit signal voltage will be with the brake light one light off a flashing and high and low changes. The reason for the change is when the brake light is on. As the brake light circuit has the presence of current and resistance. It will produce a voltage drop. So the signal voltage is reduced. When the brake light is off. Although the brake light circuit is still there is resistance, but no current. So there is no voltage drop. At this time the voltage of the circuit relative to the brake light when the voltage is improved. Although the brake light when a light off the circuit voltage change is not large. But it is very regular, it is similar to a negative square wave signal. This signal is received by the ABS control unit. It was mistaken for the ABS system has failed. And light ABS fault lights.
    Through the above summary of the cause of the ABS fault light light. That: for some failures do not take it for granted, since that is the A system failure. It must be in the A system to find is not necessarily correct. Speak with the saying goes Do not walk in the end Sometimes in the A system revealed the failure. The reason may be in the B system, especially with vehicles equipped with multi-module bus control system. We may wish to change a road to go. May receive unexpected results.