Summary

This guide describes hardwiring a dash cam (with two cameras) to the fuse box in the rear of a W213 wagon using a switchable fuse (powers on with ignition) and a constant power fuse (power is always on). I’m sharing this guide to help others who are considering hardwiring a dash cam in their long roof beauties. Hopefully the mistakes I made while installing a 70mai A810 dash cam will help your install go smoother and faster.

Tools

1. T45 torx bit
2. Panel trim removal tool
3. Interior trim panel retainer 000-991-86-98 (4)
4. Fish tape
5. Wire cable pulling lubricant
6. 3 amp fuses (4 regular ATC style)
7. fuse taps (2)
8. USB extension cable

Q&A

• How long did the entire process take (you should be able to do it much faster)? 8 hours which includes trips to Autozone, Home Depot, struggling to fish a cable through a rubber hose, and post-install test drive. Hopefully you can do something similar in half the time.
• Why wire cable pulling lubricant? The rubber hose around the wiring harness between the tailgate and wagon has some slack in it but fishing a new cable through it is challenging because of the soft rubber, ribs in the hose, and curve of the hose. I had a can of silicone lubricant nearby and figured it would get the job done. Nope. It was a big mistake because the lubricant broke down the rubber in the hose leaving the fish tape and power cable feeling gummy which I didn’t realize until I completed the work. After 2 hours of millimeter by millimeter pulling, my hands ached, the tips of my fingers hurt, but in the end it’s worth it to have a clean install.
• Why hardwire? To have the option of recording when the wagon is parked and the ignition off.
• Why use fuse taps? It’s easier than splicing into power and accessory cables directly and safer than wrapping wires around fuse prongs.
• Why use the fuse box in the rear of the wagon? It has switched and constant power and several empty fuse slots.
• Why use 2 fuses per fuse tap? Because I used empty slots, each fuse tap required 2 fuses to operate (see this Youtube video on
  how to install a fuse tap correctly
  .
• Why 3 amp fuses? Use what’s safe for your application to protect the wiring and dash cam, which is likely between 2 and 5 amps.
• Where did you route dash cam cables? Power from the fuse box to the front windshield cam: under the door sills on the passenger side. Power/connectivity from front windshield cam to rear cam: inside the headliner along the roof of the passenger side.
• Why route cables along the floor and roof? I wanted to avoid running cables in the headliner next to the airbags by placing them under the door sills. However, the rear dash cam’s power/connectivy cable is short and has an unusual mini plug. I didn’t want to create a custom cable to get extra length, so I compromised and ran one cable taking the shorter path along the roof, while the thicker power extension cable is under the door sills.
• What’s the USB extension cable for? Although my dash came with a long power cable, it was too short to route from front windshield to rear fusebox. I bought a 10 foot USB C extension cable to bridge the distance.

How-To

Pre-game review (30 min)

• Remove carpeted panel that hides the rear fusebox on the passenger side of the wagon and push aside the insulation. Examine the fuse box, cables to ground, and open areas along the side of the wagon that you can use to fish cable into the rear seat area.
  • 
    
• Examine the passenger side ribbed rubber hose that covers the wiring harness connected to the tailgate to the wagon. Consider how you want to route a cable to the rear windshield dash cam - along the roof or along the floor. Your situation may be different than mine because of the length of cable you have to work with.
• Examine the headliner near the windshield and consider how much cable to expose near the dash cam.
• Examine the headliner along the passenger side and see how it untucks or pulls away from the B pillar with the interior trim tool.

Part 1 (1 hour)

It’s assumed you know how to test for power in the fuse box.

• Find an open slot that has constant power (power is always on).
• Find an open slot that has switched power (power is on with ignition).
• Install fuse taps in the identified slots.
• Confirm that fuses in the taps have constant and switched power.
• Connect dash cam accessory wire to the fuse tap that has switched power.
• Connect dash cam power wire to the fuse tap that has constant power.
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• Connect dash cam ground wire to the screw attached to the frame.
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• Confirm that the dash cam is working as expected when connected to the USB power cable.

Part 2 (1.5 hours)

• From the passenger side A pillar, remove the plastic retainer labeled “Air Bag” and pull the cloth covered panel away from the frame to see how to safely place cables behind the air bag. See
  Ken KanFix’s Youtube video
  .
• Remove the plastic cover next to the glove box and faces the door with the panel trim tool. It comes off easily.
• Remove the plastic cover in the passenger foot well (there’s a fuse box there). It comes off easily.
• Remove the plastic cover that runs along the front door. Carefully pry, slide, and remove the cover. See Ken KanFix’s video.
• Remove the plastic cover that runs along the rear door.
• Remove the rear seat to get access to the side bolster. See the attached document.
• Remove the side boster to get access to the side panel. See the attached document.
• Pull away door seal/gasket as needed.
• Loosen the plastic cover that has the button to lower the rear passenger side seat to get access to the rear of the wagon. Lift the metal retaining tabs away from the frame.
• Insert fish tape from the rear seat and along the side of the body and above the rear wheel to the fusebox.
• Pull the fish tape and power cable and connect with USB extension cable.
• Position cable under the door sills, under carpet, along the side of the dashboard, and safely inside the A pillar.
• Hide power and connectivity cables under the headliner above windshield using a panel trim tool.
• Phew! Take a break.

Part 3 (1.5 hours)

• Remove the 1-piece plastic and rubber trim from the tailgate using the panel trim tool to pop-off 4 pink plastic rivets.
  • Note that the rivets are one time use and must be replaced with new ones to avoid water leakage.
  • The used rivets have a foam washer that are compressed and will be flattened or torn.
  • 
    
    
• Detach the ribbed rubber hose from the tailgate on the passenger side.
  Watch how Ken does it
  .
  • 
    
• Insert the fish tape into the hole along the roof and push it along the passenger side to reach the A pillar.
  • Keep the fish tape away from the air bags. There are metal brackets near the air bags you can feel with your fingers. Use the brackets to position the dash cam cable away from the air bags.
• Connect the fish tape with the power/connectivity cable that goes to the rear windshield cam and pull it back out so you have enough cable to work at the tailgate.
• Using the fish tape, insert the dash cam’s power/connectivity cable into the ribbed rubber hose that goes to the rear windshield.
  • Use lubrication and go slow to avoid tearing the rubber hose.
  • Pull down the rubber ribs over the cable rather than forcing the fish tape.
  • Pushing the cable while pulling helps a lot.
• Separate the fish tape and power/connectivity cable.
• Ugh! Take a break.
• Insert just the fish tape from the center of the windshield and beneath the trim there to eventually find the hole where the wiring harness and rubber hose are.
• After fishing around, the fish tape should appear in the hole. Reattach the power/connectivity cable and pull the fish tape back out with enough cable to reach the rear dash cam.
• Almost done!

Part 4 (1 hour)

• Connect both dash cams to the cables and confirm that the system works as expected.
• Clean windshields and stick cams to the windows.
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• Position cables in their final position.
• Cover up all exposed areas.
• Sit back and marvel at your handiwork!