DashcamCraft Practical Guide
An ACC fuse has power only when the vehicle is on; a constant fuse remains powered with the ignition off. A three-wire parking-mode kit normally uses both so the camera can recognize ignition state.
Quick answer
An ACC fuse has power only when the vehicle is on; a constant fuse remains powered with the ignition off. A three-wire parking-mode kit normally uses both so the camera can recognize ignition state.
What each circuit does
ACC or switched power tells the camera when the vehicle is running. Constant power supplies limited energy while parked. Ground completes the circuit. The hardwire kit controls the transition and low-voltage cutoff.
How installers identify them
Circuit behavior must be measured with suitable test equipment in both ignition states. Fuse labels alone are not enough because layouts and behavior vary by vehicle.
Safe selection checklist
Avoid safety-critical systems; confirm fuse rating and direction; use the correct fuse-tap size; preserve the original fuse; secure the ground; configure voltage protection; test drive and parking behavior.
Common mistakes
Using two constant circuits, choosing a retained-accessory circuit without testing, reversing fuse-tap orientation, poor grounding, or assuming a spare slot is suitable can cause unreliable operation.
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