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Testing automotive headlight leveling device?

Discussion in 'Troubleshooting and Repair' started by apples, Apr 18, 2014.

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  1. apples


    Jul 1, 2012
    I have a headlight that does not level. It is out of an Iveco Daily van, the pass. side light will adjust up and down you can see it and hear the motor working. On the drivers side, nothing.

    I have pulled it out, and pulled the little motor off, it works when hit with 12V.

    The IC on the board is a TLE 4209 A , here is a data sheet:

    Is there any way that I can test this?
    I have three pins, one would be ground, one 12v for clockwise motor rotation the other pin for anti-clockwise motor rotation. Have also tried powering the pins in all possible combinations with 12V, nothing happens.

    So what do you do in a situation like this if you want to fix it? Just replace that IC?
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    figure 3 in the dataheet shows a typical application circuit. In the headlight there is probably a similar circuit being used. Potentiometer Pref would define the set angle of the headlight, potentiometer Pfb would give the actual angle. The IC will then turn the motor until the voltages from Pref and Pfb to the IC's pins 8 and 1 are equal.
    Measure the voltages at Pins 8 and 1. What are their values?
    If you manually turn the motor (or gear or whatever controls the angle of the headlight), does the voltage on pin 1 (or 8) change?
    How is the set voltage for the angle created? Is it manualy adjusted or is there some automatic? Does this voltage, presumably on pin 8, change whenthe set angle is changed? (note that pins 1 and 8 may be swapped, that wouldn't affect the operation).
    Measure voltages always from a measurement point (e.g. pin) to GND.

    If you see a voltage diference between pins 1 and 8 (a few millivolts are o.k.) and no change at the outputs (pin 3 and 5) chances are vey high that the IC is defect.
    If you see no change in voltage at the inputs when you either set a new angle or manualy adjust the actual angle, the sensor or the set poentiometer are defect. Note that not necessarily potentiometers are used in the actual device, the control voltages could be generated by other means, too.
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