【Inspection process】
    After checking the battery at the start of the voltage is too low (less than 9V), auxiliary start, check the engine control unit fault memory has a fault code 16955: brake light switch a F unreliable signal. Because it is accidental failure, so the direct elimination of the. Check the battery pole voltage with a multimeter to about 14V, which means that the generator is normal. After charging for a while, turn off and start again. The results of a successful start. So you can initially determine the battery is normal. Failure may be due to a flame after a work to continue to work, resulting in battery power loss, can not start. Will inform the owner of this situation, the owner suddenly remembered half a month ago found in the sun exposure for a long time after the parking, the brake light will be bright. Ask the owner of the high brake light is bright, the user said not bright, and said the car into the shade of the tree for some time or after driving for some time, the brake lights will automatically extinguish the owners did not care too much.
    【Fault Analysis】
    Associated with the brake light switch unreliable signal of the fault code, then suspected brake lights after the discharge. Will V, A. S5051 50A current clamp clamped on the battery negative line. Enter the multimeter function. When the flame lock car is shown to be about 240mA. After 10s after the change to 33mA or so, are in the normal range. The vehicle on the sun exposure for 2h. The brake light is not bright, so the analysis may be the same day the temperature is low, if the hot weather and prolonged exposure to the sun, the car temperature will be very high, the brake light switch may be due to thermal expansion, resulting in internal contact abnormal closure The So that the brake light is lit. While the high brake light and taillight assembly within the brake light is the same line. Parallel relationship. Should also be lit at the same time, may be due to poor contact contact, contact resistance. The partial pressure causes the voltage on the brake light to decrease. Light brightness is small or may be the angle of the reasons, reflective, the owner did not find high brake light is also bright.
    【Maintenance】
    The final decision to replace the brake light switch. Let the owner observe for some time. After a long time observation failure no longer occurs.