CR-Z Factory Navigation: Adding Auxiliary Video Inputs via a Navtool Interface

The one mandatory part is the Navtool interface (Part#NAVRGB / Part#HONDARIB); substituting a different piggyback unit will invalidate this procedure. Order it and download the manufacturer's instruction sheet, then concentrate on the page written specifically for Honda navigation units, since that section explains where the interface taps into the screen. The manual's English is rough, so read it through several times before touching the car. Budget roughly $180 to $220 for the interface; sellers frequently accept a best offer below the listed price.

Lay masking tape around the head unit to shield the dashboard finish. You may leave the battery connected so you can verify live circuits later, but then treat every exposed wire as energized. Gently lever off the plastic trim beneath the radio and unplug the small courtesy light, which exposes an 8mm bolt; remove it. A small 8mm hex fastener behind the unit must be levered against to pop the head unit free. Keeping pressure on it is fiddly, so a stiff flat tool or the jaw of a wire stripper often works better than a screwdriver. With the unit loose, turn the key to ACC to motor the screen into its open position, then switch back to off. Release the awkward locking connector at the rear by pressing its lever with a thin flat blade, and withdraw the unit.

The navigation assembly is held to the trim by eight 8mm screws. They are Phillips-headed, but an 8mm socket grips them far more securely and avoids stripping. The four screws along the sides of the screen are the crux of the entire job; they behave as if cemented in from the factory. Flood them with penetrating lubricant and let it soak thoroughly before applying a Phillips 00 or 0 driver. Expect some to strip, so keep a screw-extractor set with reverse-cut bits on hand. If a screw simply will not move, drilling it out is the last resort, but accept that doing so permanently ends any future use of the disc mechanism.

With the housing open, disconnect the factory video ribbon feeding the LCD and fit the Navtool ribbon in its place, following the Honda page of the interface manual. Keep the original ribbon safe: if the interface ever fails, it can be swapped back to restore the standard navigation display. No soldering is required at the ribbon, but this connection is what lets the interface override the on-screen image, so seat it carefully and confirm it is fully home.

Power the interface from an accessory (ACC) circuit so it is only live with the ignition on. Use a mini fuse tap (ATM Mini blade type) in the cabin fuse panel rather than cutting into the main 12V harness plug behind the radio; this keeps the critical factory feed intact and reduces the chance of disturbing the primary supply. Fit an appropriately rated mini blade fuse in the tap.

Input 1 is toggled by opening a circuit, so it needs a manual switch. The supplied switch is crude; a plain 12V round rocker with a 20mm / 13/16 inch mounting diameter is a tidier substitute. Identify its +12V and ground terminals. Reach up behind the fuse-panel opening and pop out the small rectangular blank in the dash (on other markets this blank holds a folding-mirror switch). Drill a 13/16 inch hole in the blank with a step drill bit, practicing on scrap first to get a clean, centered hole, then drop the rocker into place. Extend the interface's switch leads as needed with 20AWG wire, crimp 4.8mm x 2.0mm female terminals onto them, and push them onto the matching switch prongs before clipping the blank back in. Note that a rocker with a built-in LED generally will not illuminate from these leads, so a plain switch is perfectly acceptable.

Input 2 activates when +12V reaches its blue trigger wire, and it always overrides whatever is on screen. The CR-Z carries a wire behind the radio that goes live only in reverse. Confirm it with a multimeter first: with the head unit out, start the car and shift into reverse, checking that the wire reads roughly 12V only in R. Splice the interface's blue wire into that feed. A poor splice here is the most common failure. One builder could never get Input 2 to fire and traced the fault to a bad tap, so make the joint clean and re-test it. Pairing this trigger with a reversing camera powered from the rear white reverse bulbs yields a camera view that appears automatically whenever the car backs up.

The interface provides two RCA composite inputs. Wire your manually selected source, such as a DVD player, phone video adapter, or TV tuner, to Input 1, and a reversing camera or similar device to Input 2. Remember that the factory head unit cannot decode DVDs on its own; any disc or TV source requires its own external player. Route camera or antenna cabling toward the rear by lifting the door weatherstrip and tucking the wire behind the interior trim panels.

Reverse the disassembly: seat the navigation unit back on its mounting rails, refit the housing screws you were able to save, and carefully return the head unit to the dash while managing the trailing harness and ribbon. Reconnect the plugs, refit the lower trim and courtesy light, and remove the masking tape. When power is restored, the head unit will request its anti-theft stereo unlock code, so have that code ready before you begin.