In lieu of hiring a professional and spending a lot of money to install a car headrest monitor, if you are handy and electronically savvy, this is a do-it-yourself project that can be completed without too much trouble.
One way of installing the monitor is to hard wire cables into the car. This necessitates removing interior trim panels and is quite labor-intensive. You'd need to connect all grounds to the same location by using an “add-a-circuit fuse” to the fuse box. Most systems will require a five amp circuit, and also, it's essential that you remember to disconnect the battery’s negative terminal before making any connections.
An easier way to complete a headrest installation would be to connect the wiring for the unit. This process involves more than just plugging the wires in, however. They must also be run through the seat to keep them out of sight and safe. It's not that difficult to do, but it's highly important that you take your time with it so that the end result will not only look good but work correctly as well.
Step 1 - Replace the Headrest Posts with Hollow Ones Through Which Wires Can Be Run
Measure the posts to see what diameter you will need. Remove the headrest. Some headrests have buttons on the mount next to one of the post holes. By holding this button in while pulling out the post, you can remove the headrest. Other headrests have pinholes that must be pushed in using a paperclip or pen tip. Unscrew the current posts. Run the wires through the new posts and screw them into the headrest. Replace the headrest
Step 2 - Remove the Seat-Back
Don’t force anything, and be careful with this step because you don’t want to rip a seam. Some seat-backs have snaps. Pop out the tabs at the bottom of the seat-back, and then take a screwdriver and ease out the sides and top off the seat. Other seats have screws at the bottom of the seat-back. Undo the screws and slide the seat-back down to remove it. Finally, there are fully upholstered seats. For these seats, you need to lean the seat back all the way, unclasp the back, and pry apart the plastic teeth that hold the seat-back to the seat.
Step 3 - Run the Wires Down The Back of the Seat
The bottom of the seat has a plastic and carpet lip that can pulled back easily. Run the wires beneath the metal at the bottom of the seat back and through the upholstery also at the bottom. Replace the seat back cover
Step 4 - Connect the Wires
There are two wires: the A/V input and the A/V output, which is also the power cable. Line up the tabs of the power cable to the end of the RCA output cable and connect them. Do the same for the A/V input with the other RCA cable.
Step 5 - Connect the DC Power Jack into the Cigarette Light
Connect the two positive side wires to each other to protect the headrest and fuses and to insulate the positive side. The ground can stay loose.
Plug the connector into the outlet in the car, and you are ready to go!