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 table below summarizes the input signals to and output signals from the headlamp control module (HCM). The signal types are divided into directly connected signals, serial communication and CAN communication. The illustration below displays the same information with the Volvo component designations.
| Input signals: | Output signals: |
| Directly connected: | Directly connected: |
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| Via serial communication: | Via serial communication: |
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| Via Controller Area Network (CAN) communication: | Via Controller Area Network (CAN) communication: |
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NO RELATED
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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.