Most people plug their dash cam into the cigarette lighter.
That makes the cam die when the engine stops.
It also clutters your dash and steals your charger.
If you want parking recording or overnight security, don’t do that.
Hardwire the camera instead.
This guide shows three clean ways to power a dash cam.
You will learn the quick mirror method, the OBDII trick, and the fuse-box install.
The Basics: ACC, Constant, and Ground
Know these three terms before you touch wires.
- ACC (Accessory). Power only when the car runs. Use it for driving footage.
- BATT (Constant). Power all the time. Use it for parking mode.
- GND (Ground). The negative wire. Connect to bare metal on the car.
If you want parking security, you must use a constant power source.
Read our tests for parking cams to learn more: Best Dash Cam for Vandalism and Parking (2026 Test).
Method 1: Mirror Adapter — Clean and Fast
Difficulty: Very easy
Time: ~5 minutes
Best for: Leased cars and quick installs
Many rear-view mirrors have built-in power.
You can tap that power with a small adapter.
Plug the adapter into the mirror harness.
Then plug your cam into the adapter.
Pros:
- No visible wires.
- Fully reversible for leased cars.
- Fast and neat.
Cons:
- Usually no parking mode.
Deep Dive: We have tested specific mirror adapters for popular trucks and SUVs.
* Ford Owners: Best Dash Cam for F-150 Reddit 2026
* Toyota Owners: Best Dash Cam for Toyota RAV4 (OEM Look)
* General Guide: Best Fuse-Free Dash Cam for Easy Installation
Method 2: OBDII Power Cable — The Lazy Hardwire
Difficulty: Easy
Time: ~10 minutes
Best for: People who want parking mode without fuse work
The OBDII port often has a constant power pin.
Buy an OBD-to-USB power cable and plug in.
Your cam can run 24/7 this way.
Pros:
- Instant parking mode.
- No tools or fuse taps.
Cons:
- Blocks the OBD port for diagnostics.
- Cheap cables may lack a voltage cutoff. That can drain your battery.
For OBD info and scanner tips see: Best OBD2 Scanner Reddit (2026).
Method 3: Fuse Box Hardwire — The Gold Standard
Difficulty: Moderate
Time: 45–60 minutes
Best for: Permanent installs and full parking protection
This is the pro method.
Use a hardwire kit and fuse taps.
Tap one fuse for ACC and another for Constant.
Ground the black wire to bare metal.
Step 1 — Find the fuse box
Check your owner’s manual.
Most boxes sit under the dash or behind the glove box.
Step 2 — Pick safe fuses
Do not tap safety systems like airbags or ABS.
Good ACC picks: cigarette lighter, radio.
Good constant picks: interior lights, power seats, horn.
Luxury cars and newer BMWs may show battery errors if you tap wrong. See our BMW guide: Best Dash Cam for BMW (2026): Stop Battery Drain Errors.
Step 3 — Fuse tap orientation (critical)
A fuse tap is directional.
If you install it backward, the cam may not be fused.
Test the socket. One side is “hot.” Use a circuit tester.
Align the tap so the hot side feeds the tap input.
Step 4 — Grounding
Attach the ground to bare metal.
Do not use painted bolts or plastic supports.
A clean metal contact is required.
Step 5 — Set the voltage cutoff
Hardwire kits let you cut power at low voltage.
Suggested settings:
- Summer: 11.8V
- Winter: 12.2V
Cold cuts cranking power. Use a higher cutoff in winter.
Safety Note: This is why we often recommend Super Capacitor dash cams over Lithium Battery cams, especially in extreme weather.
* Read More: Best Dash Cam for Extreme Cold Weather
Routing the Wire — Avoid the Airbag
Hide the cable in the A-pillar. Do it right.
Many cars have curtain airbags in the A-pillar.
If the wire sits in front of the airbag, it can turn into a dangerous projectile.
- Remove the A-pillar trim fully.
- Place the wire behind the airbag tube.
- Zip-tie to the factory harness.
This keeps the wire clear of any deployment path.
Wiring Hacks: Determining “Hot” Side
Fuse taps have a direction. If you put them in backward, current flows through the fuse tap first, meaning your dash cam is unprotected.
Quick Warnings
- Never tap into Airbag (SRS), ABS, ECU, or Fuel Pump fuses.
- Do not let the dash cam draw power without a proper fuse.
- Avoid cheap OBD cables that lack battery protection.
- Consider a super-capacitor cam for extreme heat or fire-risk concerns. See: Capacitor vs. Battery Dash Cams: Fire Hazard You Should Know.
Final Summary
- Use a Mirror Adapter for a clean, reversible install. Read: [Best Fuse-Free Dash Cam for Easy Installation (2026)].
- Use an OBDII cable if you want parking mode fast and easy.
- Use a Fuse Box hardwire for the safest, most reliable 24/7 setup. Read: Best Dash Cam for Uber (Reddit Consensus 2025) for pro installs.
Hardwiring takes time. Do it once and do it right.
Use a Mirror Adapter if you are leasing the car or hate wiring. (Read our Leased Car Guide)
Always Check Voltage if you live in high-heat areas, as batteries swell and drain faster. (Read our Heat Survival Guide)
