BMW F3x Adaptive Xenon Retrofit [Full Guide]
This article will walk you through the process of upgrading from xenon to adaptive headlights. If you’re starting with a halogen headlight, you’ll need to follow the “halogen to xenon” retrofit guide.
The VO coding and two extra K_CAN2 cables are the sole differences between xenon and adaptive wiring.
F3x Xenon to Adaptive Xenon Retrofit (AHL)
I recently completed this refit for a colleague. He purchased a damaged F32 4 Series with xenon option 522, then purchased the incorrect headlights – adaptive AHL xenons (option 524).
I suggested he get a new, correct set, but he refused. He must have reasoned that it would be easier to make this one work than to find another set. At least for him.
Replacing the headlights
Note!
If you don’t have access to a headlight adjustment device make sure to at least “copy” the settings from the current low and high beam lights.
Basic Headlight Adjustment
Place your BMW 15–30 feet in front of a vertical wall (5-10m). Dim lighting can be really beneficial (eg. turn the lights off if you are in a garage, or find a darker space if outside).
Take some adhesive tape or a marker (maximum 2cm, or under an inch).
First, use adhesive tape or whatever you like to mark the horizontal light-dark boundary on the wall. Mark the lateral position next as follows:
Left Headlight: cover right headlight and mark the vertical and lateral light-dark boundaries on the wall
Right Headlight: cover left headlight and mark the vertical and lateral light-dark boundaries on the wall
You can use these marks for reference when you install the new headlights so you’ll have at least 90-95% correct adjustment.
Note!
Set the steering wheel straight ahead after completing the adaptive headlamps installation. The visual is enough. Adjust the headlights vertically first. Check the vertical adjustment after you’ve adjusted them laterally! You’ll have to tweak them a few times.
Now you can replace the headlights.
After removing the headlights, I recommend first taking care of the wiring and then installing the new headlights.
How to Replace the Headlights
Remove the front bumper panel.
Remove the rubber gasket (1) and the screws (2) that are beneath it with Torx T30.
Under the bumper panel, remove the screws (1) and, if necessary, the expanding rivet (2), depending on the bumper version.
Remove the screws (1) with a 8mm socket on the left and right wheel arch covers.
Move the wheel arch cover a bit (2).
Remove the screws (1) with a 8mm socket (two at each side).
Pull bumper panel (2) forwards a little.
Unlock and detach plug connections on the following components depending on the version.
- Ultrasonic sensors PDC (right wiring harness)
- Pedestrian protection sensor (right and right wiring harness)
- Ultrasonic sensors for parking maneuvering assistant (left/right)
- Fog light (left/right)
- ACC sensor (middle)
- Side View Camera (left/right)
If necessary, unlock and detach the hose pipe for the headlight cleaning system and lay down on top.
Remove bumper panel (2) towards the front.
Only M bumper:
Unfasten mount (1) from catch in version with M Aerodynamics package (2).
Remove the forward bumper trim panel.
Now proceed with headlights removal.
If the retaining clip (2) is present, the central connector on the headlight cannot be disconnected!
Release screw (1) and remove retaining clip (2) if necessary.
Unlock and remove cover (1).
Unlock plug connection (1) and disconnect.
Unfasten screws (2).
Release screw (3).
Release screw (1).
Carefully remove headlight (2) in the direction of the arrow.
US version: Check / position the horizontal blocking when headlight is replaced
Before installing the new headlamp, make sure that the headlamp adjustment screw for lateral adjustment is secured against tampering with a plug.
Check:
Check the adjustment screw for horizontal adjustment for blocking (schematic diagram) For the precise location of the adjusting screws, if necessary, refer to the vehicle-specific documents for the headlamp setting)
Desired state:
The adjustment screw for side adjustment must be blocked with a plug (1) (schematic diagram)
Result:
Plug (1) is mounted in the the horizontal adjustment screw (schematic diagram))
Measure:
Install headlight
After installation, check vertical headlamp setting and correct if necessary
Result:
No plug is fitted in the horizontal adjustment screw (1) (schematic diagram)
Measure:
Mark the position of the horizontal adjustment screw to identify a possible adjustment of the adjustment screw after mounting the horizontal lock (schematic diagram).
Insert the headlamp-specific plug (1) into the adjustment screw (2) without damage (schematic diagram)
Attention: After installing the plug (1), check the correct position of the adjustment screw (2) according to the markings applied and correct if necessary.
Install headlight
After installation, check vertical headlamp setting and correct if necessary
Now we are ready for wiring.
Retrofit Wiring Harness
To make the AHL headlights work, simply add two CAN wires to each socket and link them to any point on the K CAN2 network. For cleaner installation and easier future troubleshooting, the best option is to connect them directly to the FEM module.
Two twisted CAN low and CAN high cables should be made.
Unfortunately I never measured the required length of the cables, but some 7 feet for the right side and 10 feet for the left side would be enough.
Xenon 522
Add K_CAN2_H and K_CAN2_L wires to the headlight connector:
K_CAN2_H to headlight connector pin 9
K_CAN2_L to headlight connector pin 10
Remove the rubber grommet seal from the connector slots for pin 9 and 10.
I don’t have a perfect tool for removing these small seals, but I use the tool for removing the pins. Sometimes they go out easily, and sometimes they are real PIA.
With the seals out of the way, insert the CAN wires in their respective slots.
Now you’ll need to route the cables all the way to the FEM module located in the passenger footwell A pillar.
Here is the routing for the right headlight you should follow from the right headlight connector (E5*1B) to the cabin. Secure the cable with cable ties.
Drill a hole through the cable grommet with a tiny drill bit (1). When drilling, be careful not to harm other cables. Route the K CAN2 twisted cable to the FEM module in the cabin.
Here’s the routing for the left headlight.
How Does Adaptive Xenon Work
If you are still at the deciding point of your project, let me explain what you’ll get if you opt for adaptive xenons.
When it comes to adaptive xenons, the first thing that comes to mind is that the lights can turn in tandem with the steering wheel. However, adaptive xenon is capable of far more than just turning low and high beams.
So, let’s take a look at what you’ll actually get with this retrofit.
Adaptive headlight beam throw adjustment
When driving through dips and crests, the adaptive headlamp beam throw adjustment is activated. The headlight driver module (TMS) operates the swivel module through the stepper motors in response to a request from the front electronic module (FEM), adjusting the headlight beam throw.
The headlight beam throw is raised while you drive through a dip. The swivel module has been shifted upwards. As a result, a longer distance of the road is lighted.
| 1 | BMW without adaptive headlight beam throw adjustment |
| 2 | BMW with adaptive headlight beam throw adjustment |
The headlight beam throw is reduced when you pass over a crest. The swivel module has been significantly lowered. An oncoming vehicle’s blinding effect is reduced as a result.
| 1 | BMW without adaptive headlight beam throw adjustment |
| 2 | BMW with adaptive headlight beam throw adjustment |
Variable light distribution (depending on the national-market version)
The variable light distribution illuminates the road ahead of your BMW more evenly. Again, the headlight driver module operates the swivel module through the stepper motors in response to a request from the FEM module, adjusting the light distribution.
Individual light distributions have smooth transitions between them.
In conjunction with the ”Adaptive Headlight” optional equipment, the following variable light distribution are available:
Engine start
Both headlights run a reference run in switch position “A” (light switch in the switch position for automatic driving lights control) and ignition on. That is, both swivel modules are lowered slightly before being adjusted to the ideal position (visible when the vehicle is parked in front of a wall: The light cone moves down and then back up). The target position is determined by the vehicle’s load state.
When you start the engine, the headlight driver module initially sets the mode for city light distribution.
City light distribution
At low speeds, the city light distribution allows for a broader illumination of the left side of the road. The link headlight is shifted 12 degrees to the left and 0.7 degrees downwards. From engine start to a speed of about 30 mph, the city light distribution is engaged.
Country road light distribution
The distribution of country road lights is identical to that of standard low-beam headlights. The city light distribution changes to the rural road light distribution when your driving speeds exceed 30 mph. The front electronic module (FEM) adjusts the light distribution back to the city at speeds below about 30 mph.
The base setting for the headlights is the country road light distribution. When there are failures in the entire light distribution system, the basic setting is activated.
Motorway light distribution
The motorway light distribution extends the driving light’s range. The left headlight is shifted 3.5 degrees to the left and 0.25 degrees downward. The right headlight is angled upward by about 0.2 degrees.
The FEM module turns on the motorway light distribution if the vehicle speed exceeds 70 mph for more than 30 seconds, or immediately if the vehicle speed exceeds 85 mph.
The headlights are gradually reset when you slow down below 70 mph, depending on the driving speed. This happens in four stages (70 mph, 62 mph, 55 mph, and 50 mph). At 50 mph and slower, the country road light distribution is again reactivated.
Fog light distribution
TWhen the fog lights are turned on, the fog light dispersion is engaged. The fog light dispersion can be coupled with both city and country road lighting.
The link headlight is shifted 8 degrees to the left and 0.7 degrees downwards. When the high beam headlights are turned on when the fog light distribution is on, the headlight returns to its default setting, which is the country road light distribution.
| 1 | City light |
| 2 | Fog light |
| 3 | Country road light |
| 4 | Motorway light |
- Adaptive Headlights
The footwell module (FRM) is the control unit for the Adaptive Headlight. The Adaptive Headlight system turns the bi‐xenon headlights towards the inside of a bend when cornering. Horizontal movement range of headlights:- Inwards, i.e. towards center of vehicle: up to max. 10°
- Outwards: up to max. 15°
- Example of a right-hand bend: The right-hand headlight turns by up to 15° (the right-hand headlight is the ”inside” headlight on a right-hand bend). Viewed from the vehicle, the right-hand headlight moves ”outwards”. The left-hand headlight moves up to 10° (the left-hand headlight moves towards the middle of the vehicle, i.e. ”inwards” as viewed from the vehicle). The outer headlight (left headlight) must reach its end position at the same time as the inner headlight (right headlight) to ensure that the road is illuminated in a steady and uniform manner.
The footwell module transmits the setpoint values for the swivel modules via the LIN bus to the headlight driver module (position of the swivel modules and speed of the swivel movement). In accordance with the input signals from the footwell module, the headlight driver modules activate the stepper motors to adjust the swivel modules in the headlights.
| Index | Explanation |
| 1 | The Adaptive Headlight pans to the right |
| 2 | The Adaptive Headlight is moved to the right |
Cornering lights (optional equipment)
| Index | Explanation |
| 1 | Turning left |
| 2 | Turning right |
At driving speeds greater than 70 km/h, the cornering light is no longer activated by the footwell module (FRM).
When reversing, the footwell module switches the cornering light on up to a speed of 40 kph:
- US version: both sides
- Other countries:
- Turn indicator activated: side of the active turn indicator
- Steering angle (turn indicator not activated: side on the outside of the curve only
When the turn indicator is switched on: If the vehicle is stationary, the turning lights will automatically be deactivated after approx. 4 seconds, e.g. when waiting at traffic lights. However, the turning lights can be activated again with the turn signal/high beam switch (up to 3 times) until the reflector has reached a certain temperature. A temperature model in the footwell module (FRM) protects the headlight against excessively high thermal loads. If a critical temperature is reached, the cornering light is switched off. After a cooling-down period, the cornering light can be switched on again.
