Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Automatic Headlight Levelling
For vehicles without Four-C (Continuously Controlled Chassis Concept), the position sensors (7/119, 7/121) for rear wheel suspension and front wheel suspension send information to the headlamp control module (HCM) (4/118) on vehicle angle as regards load conditions, acceleration and braking.
For vehicles with Four-C (Continuously Controlled Chassis Concept), the suspension module (SUM) (4/84) sends information to the headlamp control module (HCM) on vehicle angle as regards load conditions, acceleration and braking.
The headlamp control module (HCM) uses the information from the position sensors or suspension module (SUM) to calculate the actual angle for the headlamps.
For vehicles with active headlamps, the headlamp control module (HCM) transmits information on the actual angle to the left headlamp control unit (LHCU) and right headlamp control unit (RHCU) via serial communication. The adjustment motors are then controlled by the left headlamp control unit (LHCU) or right headlamp control unit (RHCU), respectively, via an analog signal.
For vehicles without active headlamps, the headlamp control module (HCM) regulates the relevant adjustment motor via a signal.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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