From 2 years ago, the instrument panel appeared headlight automatic leveling fault symbols, intermittent and occasional, but also ignored, does not affect driving. When I went to the repair shop, the worker could not read the fault code with the OBD special instrument. There is no way to eliminate this malfunction.
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The fault light on the flat road jumps out and rings every time. The slope road disappears again. There are also acceleration and deceleration, over and over again. It’s finally a nuisance.
After some search, we know that the headlight automatic leveling depends on the feedback signal of the height sensor before and after the chassis to automatically level the ECU,ECU according to the front and rear height, and the motor in the headlight sends instructions to adjust the illumination angle of the headlamp.
Start with the line according to the procedure of the maintenance manual.
Headlamp automatic leveling ECU after the glove box, check the connector C107, plug and pull to see that the contacts are normal. There is also a connector C125 on the left side of the driver’s foot, which is normal after inspection. The problem may be the chassis sensor, so take it off.
Remove the right front wheel, find the height sensor, loosen the screw, pull the plug, and take it out.
Similarly, remove the right rear wheel, loosen 3 small screws, and remove the sensor.
It is found that the lubricating oil of the ball head in these two places is dry and the hairpin of the connecting rod is not flexible.
After cleaning with a little oil, it is much more flexible. Could it be the fault for this reason?
Or check whether the electrical performance of the height sensor is normal, and take out the stabilized power box on my old computer, which can provide 12V, 5V, 3.5V DC voltage.
There are 3 contacts in the sensor socket. Contacts 1 and 3 are positive and negative poles of the power supply with a voltage of 5V. The 2 contacts in the middle are feedback signals.
According to the test method in the maintenance manual, measure the change of voltage on contact 2 after rotating the sensor connecting rod.
As the angle rotates, the voltage varies from 0.5V to 4.5V.
Mark at 2.5V, this angle should be the reference angle of 0 degrees.
After the measurement, the electrical curve agrees with the figure above, and the two sensors are normal.
What’s the problem? Then measure the terminal voltage of the plug at the other end of the chassis of the car.
Before measuring, get in the car and unscrew the key, power it to ON, and don’t start the fire. The power supply voltage is 5V, which means that the line is normal.
Since it’s normal, put it back and try again.
Muttering in my heart, it is possible that the ball head of the sensor connecting rod at the back is stuck, causing the abnormal influence of the angle, so since it has been cleaned and handled, it should be eliminated.
Remove the sensor again, it seems that the bracket of the front sensor is strange, the angle is not right angle, it is deformed.
Taobao search, what is the original factory parts, as expected, the original factory connecting rod is right-angled.
Straighten the bracket with electrician’s pliers, reload the car, start the fire again, and the fault light is gone. The great task has been completed. Think carefully afterwards, it may be a long time, the sensor connecting rod ball head is stuck and inflexible, do not pay attention to driving, one time too big pit, jolted badly, resulting in the front height sensor fixed on the hem arm of the bracket deformation, affecting the angle feedback signal is not normal, headlight leveling ECU diagnosis failure. Sometimes, with the change of the inclination angle of the vehicle going up and down the hill, the fault lights appear intermittently.
By the way, the battery of the induction key has also been replaced, and recently there has been an alarm with a low battery of the key. The CR2032 button battery in the stationery store is 5 yuan, done.
CarolineOscar 
3 
September 15, 2024 
