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.
System overview: Signals
The chart below summarizes the input signals to and output signals from the headlight control module (HCM). The signal types are divided into LIN communication and CAN communication. The illustration below displays the same information with the Volvo component designations.
| Input signals: | Output signals: |
| Via LIN communication: | Via LIN communication: |
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| Via CAN communication: | Via CAN communication: |
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Use the Manual With the Right Hardware
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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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