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Navigation Installation Guide

I've been a huge fan of car audio ever since I tried (semi-successfully) to build my own custom truck speaker enclosures as a 16-year-old. I joined the Crutchfield car writing team way back in February of the year 2000, and proceeded over the years to write about nearly every product category we carry. In 2007, I assumed my current role of Car A/V Editor for our catalog, a position that helps me channel my passions for both music and driving.

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You can also download a pdf of the In-Dash Navigation Installation Guide. Note: To view this file, you will need the Adobe Acrobat PDF reader (free download).

There are several different types of navigation systems available, including in-dash DVD receivers with built-in monitors and navigation capability, remote-mount (or component) systems, and portable plug-and-play navigation pieces. This installation guide focuses specifically on installing in-dash and remote-mount navigation systems, and the special wiring connections need to be made.

Plug-and-play portables require minimal installation — most come with suction-cup mounts that attach to the windshield and a cigarette lighter adapter for power. Simply follow the few simple instructions in the owner's manual and you'll be set.

Tools needed for installation a car navigation system

In-dash, remote-mount, and certain plug-and-play navigation systems require mounting a GPS antenna. It can be placed in the car, on the rear deck, for example. However, for optimum performance, it should be mounted outside the vehicle. In this regard, it installs just like satellite radio antennas. Please see our satellite radio installation guide and our satellite radio antenna installation video for help.

For our purposes, you'll need to be able to do four things: find and make a connection to the vehicle's speed sensor, find and make a connection to the reverse light, install the navigation module, and make all the power and audio/video connections. (If you're not connecting the DVD-ROM drive to an in-dash receiver with a monitor, you'll need an external monitor. Front-seat external monitors usually come with adjustable mounting brackets; their owner's manuals feature mounting details.)

Finding and connecting to the speed sensor

Your car's speed sensor sends speed information from the transmission to the speedometer. Some navigation systems use this information to calculate speed and distance, and to estimate time of arrival during the course of a trip.

Many navigation systems no longer use this connection, relying exclusively on the information received from GPS satellites to track your vehicle. That means you might be able to skip this step. But for those navigation systems that do require this information from your vehicle, you'll have to find and make a connection to your car's speed sensor wire.

Vehicle speed sensor
Speed sensor wire location varies; it may be under the hood, as pictured above.

Where the wire is depends on the vehicle. Sometimes it can be accessed from under the dash, sometimes from under the hood. You'll need to consult a comprehensive wiring diagram for your vehicle in order to identify it correctly. Make sure you feel comfortable with this. If not, you'll probably want to have your navigation system installed by a professional.

If the speed sensor wire is under the dash, you can run the lead to the navigation module under the carpet on your vehicle's floor. If the wire is under the hood, you'll have to get the navigation system's lead to it through the firewall.

Preferably, you'll want to locate a hole on the firewall of your vehicle; most cars will have a predrilled hole through which some of the car's wiring already runs. If you can't find one, you'll have to find a good place to drill one — take care not to drill through a gas line or electrical wiring. We recommend that you drill your own hole only if necessary.

When running a wire from under the hood into the cab through the vehicle's firewall, we recommend you find and use a pre-existing opening, where other wires come into the vehicle cab.

Once you've found or drilled a suitable hole, run the speed sensor lead through the hole into the engine compartment, the connect it to the speed sensor wire. (If you've drilled the hole, install a rubber grommet in it to prevent damage to the lead.)

Wire taps
Using a wire tap and female disconnect is the easiest way to make the wiring connections you'll need.
Wire taps
The wire tap clamps on the wire you're connecting to; the female disconnect crimps onto the new wire you're connecting.
Wire taps
The female disconnect slides firmly onto the end of the wire tap, making a secure connection.

Once you find the wire, simply connect the navigation system's speed sensor lead to it. The easiest way is to attach a wire-tap to the car's wire and connect the navigation system's lead with a female disconnect. For an even stronger connection, you can strip away some of the jacket from the car's wire — be sure not to break the wire itself — then wrap the exposed end of the navigation system's lead around the exposed wire and solder the two together. Wrap electrical tape around the connection or use heat-shrink tubing for strength and insulation.

Finding and connecting to the reverse light

Wire taps
As with the speed sensor, a wire tap and disconnect provide a convenient connection.

As with the speed sensor, some navigation systems need to be connected to your vehicle's reverse light; the system needs to know when you're going backwards for accurate positioning and route calculation. As on the previous page, it's possible that your system won't need this connection.

If your system does require this step, the easiest way to do it is to connect to the reverse light wire right at the tail light. As with the speed sensor, you can consult your wiring diagram in order to find it. You can also check each wire that goes into the taillight with a multimeter; connect the multimeter to a wire, have someone put the car in reverse (while keeping the brake engaged, of course), then see if you get a 12-volt reading. Repeat this process with each wire until you've found the right one. (Note: if you get a 12-volt reading, make sure it's because you've found the reverse wire, not the brake wire; you'll know it's the brake wire if you get a reading as soon as the brake is pressed.)

The reverse wire can sometimes be found under the dash or under the hood, but you'll have to consult your wiring diagram carefully in order to identify it correctly; tapping into it at the taillight tends to be much easier.

Tapping the reverse wire
The easiest way to connect to your reverse light is in the back of the vehicle. As pictured above, however, you might choose to make a connection under the hood instead.

As with the speed sensor, either wire-tap the reverse light wire or strip and solder it. You can then run the connecting wire from the tail lights to the navigation module. Depending on the vehicle you drive, this could involve removal of trim panels, lifting of sections of carpet, and even backseat removal (if you're running the lead from the trunk to the navigation module in a passenger car).

Routing the wires through the vehicle

The wire routing and concealment depends upon your vehicle and where the components of your system are placed. The instructions below address, in general, what panels may need to be removed and how they typically come off. Often, panels can be pried up at edges. Screws and retaining clips might also be present that will require removal (Figure 1). To prevent damage, always use care when removing panels.

Wire Routing

Door Scuff Plate removal

The plates are usually removed by prying up the edges to release clips. Some vehicles will have screws present which will need to be removed (Figure 2).

Wire Routing

Seat Belt removal

A seat belt may be located on the panel that needs to be removed. Most seat belt anchor covers pry off. The seat belt anchor is secured with a large nut or bolt (Figure 3).

Wire Routing

Pillar Trimpanel removal

Remove seat belt if present. Remove screw covers, screws and plastic retaining clips, if present. Pry up edges of panel to remove (Figures 4 & 5).

Wire Routing Wire Routing

Kickpanel removal

Look for screws and pry-out retaining clips to remove. Pry out edges of panel to release and remove (Figure 6).

Wire Routing

Routing wire behind the dash

Route the wire behind dash and secure with plastic wire ties. Be sure that the wire does not interfere with any moving parts to ensure safe operation of your vehicle.

Routing wire for components and power connections

Determine desired locations for each component. Use the most direct route for wires. Remove panels necessary to route and conceal wires. Test system before reinstalling the panels.

Installing the navigation module

The navigation module itself, the central component, is basically a box that needs to be installed somewhere out of the way.

The box installs much like an external amplifier or satellite radio tuner. The first thing you need to do is find a good location for it. Under the passenger seat is the most common location.

Warning: removing your seat could deactivate your vehicle's SRS system.

Many navigation modules also contain a gyroscope. The gyroscope relays important direction information about the turns you make to the system. (The system uses this information in conjunction with the information it receives from the GPS satellites with which it's in contact via the antenna.) Because of this, you must mount the box completely horizontally; mounting the box at an angle will throw the gyroscope off, and cause the system to deliver incorrect in-route guidance.

Navigation hideaway box
The best place for the navigation unit itself is on the floor. For the gyroscope to work accurately, you must make sure the unit is mounted horizontally, and aligned correctly with respect to the vehicle. ("Brain box" of the Pioneer AVIC-N1 navigation receiver shown above.)

The navigation module box has four mounting feet or a mounting bracket. Once you've found the spot in which you'd like to mount the box, mark the location of the feet. You'll then have to drill holes for the screws (which are usually included). Before drilling, check beneath the mounting location to make sure you don't puncture the fuel tank, fuel lines, transmission or brake lines, etc. If all is clear, drill away. Secure the box in place with the screws.

Wiring the system

The last thing you'll have to do is make the power and signal connections.

For the system to work, you'll need to use both a constant and switched 12-volt power source. Using a multimeter can help you with this task. You'll also need to find a place to ground the navigation module — using a seat bolt usually works perfectly.

You'll run the speed sensor and reverse light leads to the box as well. Once that's done, all you have left are the audio/video connections.

Navigation hideaway box - close-up
All wires, including power, audio, and video, must be run from the navigation unit to the appropriate locations, usually under the vehicle's carpet.

Navigation systems require an external monitor for operation. If you have an in-dash receiver with a monitor, you can run a video cable from the navigation system to the receiver's video input. If you have just an external monitor, you can simply run the video cable from the navigation system to the monitor's video input. Some video receivers and external monitors feature special navigation inputs for same-brand navigation systems in addition to a standard video input. This provides the best screen resolution, frees up the monitor's standard input for another video component, and sometimes facilitates touch-screen operation of the navigation system. It also takes care of the required audio connection.

Lastly, you'll need to connect the navigation system to an audio source in order to take advantage of its voice prompts. Some navigation systems come with a small external speaker (or will accommodate an optional one); if this is the case, check your owner's manual for speaker placement tips. As mentioned above, some connect to same-brand monitors and receivers with a single cable; this is the easiest solution.

Otherwise, you can connect the audio from the navigation system to your external monitor or in-dash receiver via a set of standard RCA patch cables.

All the cables and wires, of course, have to be run from the navigation module to their various locations. To ensure neat cable runs that are out of sight, you might have to remove trim panels and pull up some of your vehicle's carpet. Though not difficult, this should be done carefully. Once the cables are connected, and the box is mounted, you're ready to navigate.

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