There are three basic types of in-car navigation systems: in-dash, remote-mount, and plug-and-play. This article will give you some tips on installation considerations for each type of system, but focuses on the in-dash and remote mount systems, since they are more involved. After reading this article, see our Navigation Installation Guide for detailed installation instructions.

In-Dash & Remote-Mount Navigation Systems

Most in-dash navigation systems consist of 3 parts: a car stereo with a built-in screen, a hideaway connection box that contains audio/video inputs and outputs, and an external GPS antenna. (Some Double-DIN size systems include all connections and don't require a hideaway box). A remote-mount system consists of a separate navigation computer (with an external antenna) that must be connected to a compatible car stereo. While the in-dash component installs just like a regular car stereo, remote-mount navigation systems require some extra wiring connections.

Vehicle Speed Sensor (VSS)
In addition to the standard power and ground leads, remote-mount navigation (and even some in-dash units) systems connect to a vehicle's Vehicle Speed Sensor (VSS) wire. Your vehicle's cruise control uses the VSS wire to determine the vehicle's speed &mdash it serves the same function for the navigation system. (Don't substitute the tachometer signal wire for the VSS wire &mdash the tach signal wire sends pulses as long as the engine is running, even when the car is sitting still.) The VSS wire sends a series of pulses (from 800 to just over 1,000 per mile) only when the vehicle is in motion. If the VSS wire is not hooked up, the navigation system will not realize that the car is moving at all, and will be unable to track position.

Reverse Signal
Many systems also connect to the vehicle's reverse (or back-up light) signal wire — this connection tells the navigation system when the vehicle is traveling in reverse. If this wire is not hooked up, then the vehicle direction will not track properly, and the navigation system won't be able to do its job.

Our highly trained Technical staff can provide VSS and reverse wire information for most vehicles — 16 hours a day, seven days a week (have your invoice handy when you call). Even if the information is not available for your vehicle, they can still help you figure out which wires are the ones you need.

Gyroscope
The gyroscope tells the navigation computer when your vehicle makes a turn. The gyroscope in a navigation device must be situated so that it points straight up and down. The gyro is set for horizontal mounting at the factory — so, in most cases, no adjustment is needed. However, an angle-mounted unit will not be able to track turns if the gyro is not set properly, and the problem should be immediately evident.

If you have to change the angle of the gyroscope:

1. Loosen the small Phillips screw directly above the gyro.
2. Using the hex key (usually supplied), gently rotate the gyro until it is horizontal to the road.
3. Tighten the small Phillips screw loosened in the first step.

GPS Antenna
The navigation computer determines its position by communicating with the Global Positioning Satellites through its GPS antenna. The waterproof antenna may be mounted inside or outside of the vehicle, but best results are usually obtained by mounting it outside on the roof.

If you opt for interior mounting, keep in mind that the GPS antenna cannot "see" through metal. Reception is also prone to electromagnetic interference when mounted in the interior of the vehicle. Do not place the antenna on the dashboard or rear deck if:

• you have a wired rear defroster
• you have metallic window tint
• you have a solar reflective window
• you have a windshield mounted radio antenna

The GPS antenna must be placed at least 5" from any physical obstruction like the "A" pillar or a 2-way communication antenna. The antenna attaches to sheet metal using a magnet or adhesive, and the cable is routed to the interior through a rear window (or door) seal.

Installing a navigation unit is like putting in an in-dash CD player or an amplifier — with a few added twists. You should have no problem setting up a navigation system if you've installed this type of equipment before.

Plug-and-Play Navigation Systems

Part of the appeal of plug-and-play GPS receivers is their ease of installation. Most plug-and-play receivers use a suction cup mount to attach directly to the windshield or your dash. Power for the GPS unit is provided by a cigarette lighter power adapter.

Simply clean a small area of the windshield (not in your direct view of the road) with glass cleaner or rubbing alcohol, and attach the suction cup to clamp it securely to the glass. Your plug-and-play GPS unit may also come with another type of installation system &mdash a bean bag mount uses a weighted non-skid rubberized pad to mount on an uneven surface, while adhesive brackets mount directly to the dash.