Many modern in-dash DVD players have safety provisions designed to prevent the driver from watching video while driving. Typically, this feature revolves around engaging the parking brake before watching anything other than a navigation or informational screen. The easiest method to bypassing most mobile DVD players is to install a switch, pressed in lieu of repeatedly engaging the parking brake.
Find the emergency brake wire on the DVD player's harness. This is usually pink or green but will be labelled in any case. Examine each wire carefully to verify which wire is used for this function.
Pull off the pre-stripped insulation on the e-brake wire by hand.
Crimp on a female spade terminal on the e-brake wire using the crimp tool.
Slide the e-brake wire to the positive side of the push switch.
Cut a piece of 16-gauge primary wire, sufficient to reach from the push switch to the head unit's installed location. Strip both ends of this wire, using the wire strippers.
Crimp a female spade terminal on one end of the primary wire. Crimp a male spade terminal to the other. The latter end will be heading toward the dash area.
Snap a T-tap connector onto the black ground wire on the DVD player's wire harness. Secure it tightly by pressing the two halves together with the needle-nose pliers until the clasp on the tap engages.
Slide the female spade terminal onto the negative tab on the back of the switch. Route the wire to the newly installed T-tap. Slide the male spade into the slot on the T-tap.
Drill two pilot holes in the switch mounting location. This should be easily accessible to the driver. Secure the switch with the self-tapping screws.
Turn on the vehicle and activate the DVD player. Press the button on the switch three to four times, until the warning message on the DVD player goes away.
Remember that laws in your area may prohibit viewing front-seat video. Consult with local law enforcement before bypassing the DVD player.