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Xenon Headlight Ride Height Sensor Testing and Replacement
 
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Pelican Technical Article:

Xenon Headlight Ride Height Sensor Testing and Replacement

Nick Czerula

Time:

1 hours1 hrs

Tab:

$100

Talent:

*****

Tools:

10, 13mm sockets, DVOM

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Height sensor

Hot Tip:

Do not touch bulbs with bare hands

Performance Gain:

Repair headlight height function

Complementary Modification:

Replace turn signal bulbs

BMW Z4 vehicles with optional high intensity discharge (HID) or xenon headlights utilize a special high voltage bulb and control unit for the headlights. The bi-xenon headlight is equipped with an electrically activated shutter which directs the low beam cone of light in the same direction as the high beam.

The headlight height is adjusted depending on suspension height. To accomplish this, BMW places a height sensor on the right front control arm. As the suspension raises and lowers, the headlights adjust to maintain proper alignment.

When the sensor fails, the headlights may not raise and lower correctly as needed, or the aim may be too high or too low. This tech article will show you how to test and replace the sensor.

NOTE: Do NOT touch the bulbs with your bare hands! Skin oil on the surface of the bulb will create a hot spot which will then cause it to burn out quickly.

Remember your car may have been serviced before and parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please include your vehicle information.

BMW Z4 vehicles with optional high intensity discharge (HID) or xenon headlights utilize a special high voltage bulb and control unit for the headlights.
Figure 1

BMW Z4 vehicles with optional high intensity discharge (HID) or xenon headlights utilize a special high voltage bulb and control unit for the headlights. The bi-xenon headlight is equipped with an electrically activated shutter which directs the low beam cone of light in the same direction as the high beam. The headlight height is adjusted depending on suspension height. To accomplish this, BMW places a height sensor on the right front control arm (red arrow). As the suspension raises and lowers, the headlights adjust to maintain proper alignment.

Working at the bottom of the right front control arm, remove the 13mm nut (red arrow).
Figure 2

Working at the bottom of the right front control arm, remove the 13mm nut (red arrow).

Working at the height sensor, uncouple the connector by pressing the release tab and pulling it straight off (red arrow).
Figure 3

Working at the height sensor, uncouple the connector by pressing the release tab and pulling it straight off (red arrow).

Working at the height sensor, remove the 10mm nut (red arrow).
Figure 4

Working at the height sensor, remove the 10mm nut (red arrow).

Rotate the sensor (red arrow) toward the left side of the vehicle and angle it up as you remove it from the body.
Figure 5

Rotate the sensor (red arrow) toward the left side of the vehicle and angle it up as you remove it from the body.

With the sensor removed, you can replace the arm or disassemble the bracket.
Figure 6

With the sensor removed, you can replace the arm or disassemble the bracket. The 13mm nut holds the arm on (blue arrow). Two 4mm Allen bolts hold the bracket on (red arrows). Reverse steps to install new sensor.

For a quick test of sensor function, turn the headlights on, then rotate the arm up and down.
Figure 7

For a quick test of sensor function, turn the headlights on, then rotate the arm up and down. The headlights should immediately react and adjust depending on arm angle. To test the circuit, you can backprobe the sensor connector. Turn the headlights on, blue arrow is terminal 1: ground. Terminal 4 (red arrow) is the signal: 5 volts unplugged. Terminal 5 (purple arrow) is reference voltage: 5 volts.

To test function of the sensor, plug the sensor back in.
Figure 8

To test function of the sensor, plug the sensor back in. Then turn the headlights ON. Backprobe terminal 4. Move the arm away from the mounting bracket (top of sensor), voltage should go high, toward 5 volts.

Headlights ON.
Figure 9

Headlights ON. Backprobe terminal 4. Move the arm toward the mounting bracket (bottom of sensor), voltage should go low, toward 0.5 volts. If you move arm up and down, voltage should vary (linear) from 0.5 volts to 4.5 volts.

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Page last updated: Sun 4/23/2017 03:00:04 AM