Garmin GPS 120XL Manual

The Garmin GPS 120XL is a rugged, waterproof marine GPS receiver designed for navigation. It features a high-contrast LCD display, 12 parallel channel GPS receiver for fast satellite acquisition, built-in worldwide basemap, waypoint and route storage, NMEA 0183 interface, and track plotting. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: Waterproof GPS unit, Power/Data cable, Mounting bracket, User manual.

Feature	Description
12-Channel GPS Receiver	Fast acquisition and tracking of satellites
Waterproof Design	IPX7 rated (submersible to 1 meter for 30 minutes)
High-Contrast LCD	4-level grayscale display for readability in sunlight
Built-in Worldwide Basemap	Includes coastlines, major lakes, and rivers
Waypoint Storage	Up to 500 waypoints with names and symbols
Route Storage	Up to 20 reversible routes with 50 waypoints each
Track Plotting	Automatic track log with 10 saved tracks
NMEA 0183 Interface	Outputs position data to autopilots, chartplotters
Backlit Display & Keypad	For nighttime operation
DGPS Ready	Accepts differential corrections for improved accuracy

Installation

Unpack and inspect contents. Choose a mounting location with clear view of sky.

1. Mount the bracket: Use provided screws to secure bracket to dashboard or console.
2. Attach GPS unit: Slide unit onto bracket and tighten locking knob.
3. Connect power: Route power/data cable to 12V DC source (boat battery). Red wire to positive (+), black wire to negative (-).
4. Connect external devices: Use NMEA 0183 wires to connect to compatible devices.
5. Secure cable: Use cable ties to prevent snags.

WARNING! Ensure power is off during installation. Drill mounting holes carefully to avoid damaging vessel.

First-Time Setup

Power on unit; follow initialization prompts.

1. Acquire satellites: Place unit outdoors with clear sky view. Unit will automatically search for satellites.
2. Set location format: Press MENU, go to SETUP > UNITS. Select Lat/Lon, UTM, or other.
3. Set map datum: In SETUP > UNITS, select WGS 84 (default) or other as needed for charts.
4. Set time: Configure time zone and daylight saving.
5. Calibrate compass (if applicable): Follow on-screen prompts.

CAUTION! Initial satellite acquisition may take several minutes. Ensure clear view of sky.

Specifications

• GPS Receiver: 12 parallel channels.
• Update Rate: 1 second continuous.
• Accuracy: <15 meters RMS (GPS), <5 meters RMS (DGPS).
• Acquisition Time: Warm start ~15 seconds; cold start ~45 seconds.
• Display: 5.2 x 3.8 cm LCD, 4 grayscale levels, 160 x 120 pixels.
• Interface: NMEA 0183 v2.0, GARMIN proprietary.
• Power: 10-40V DC, 1.5W typical.
• Waterproof: IPX7 standard.
• Operating Temp: -15°C to 70°C.
• Storage Temp: -40°C to 85°C.
• Dimensions: 15.5 x 7.6 x 5.3 cm.
• Weight: 0.45 kg.

Controls and Settings

Front Panel: POWER, PAGE, ENTER, GOTO, MARK, QUIT, ROCKER key (up/down/left/right).

Key Functions: PAGE cycles display screens (Map, Navigation, Highway, Position). ENTER selects/confirms. GOTO initiates navigation. MARK creates waypoint. QUIT exits/cancels. ROCKER moves cursor/menu selection.

Settings Menu (MENU): Setup (Units, Time, Alarms, System), Tracks, Routes, Waypoints, Interface.

Display Screens: Map (shows position, waypoints, track), Navigation (bearing, distance, speed), Highway (steering guidance), Position (coordinates, altitude, accuracy).

Connecting Devices

NMEA 0183: Connect to autopilot, chartplotter, or sounder.

1. Identify NMEA wires: GPS unit has TX (transmit) and RX (receive) wires.
2. Connect to device: Match TX to device's RX, and RX to device's TX. Share ground.
3. Configure interface: In MENU > SETUP > INTERFACE, set NMEA OUT to desired baud rate (4800 default).
4. Power: Ensure both devices share common ground.

Tip: Refer to your other device's manual for specific NMEA wiring details.

Navigation & Waypoints

Creating and navigating to waypoints.

1. Create Waypoint: Press MARK at current location. Edit name/symbol with ROCKER, press ENTER.
2. Navigate to Waypoint: Press GOTO, select waypoint from list, press ENTER.
3. Follow Route: MENU > ROUTES > SELECT ROUTE > ACTIVATE.
4. Steer: Use Navigation or Highway screen. Arrow indicates bearing; follow on-screen cues.
5. Track Back: MENU > TRACKS > TRACK BACK to reverse your path.
6. Man Overboard (MOB): Press and hold GOTO to mark MOB position and begin navigation back.

WARNING! GPS is an aid to navigation. Always use in conjunction with charts, compass, and situational awareness.

Advanced Features

Tracks: Automatically records path. Adjust recording interval in MENU > TRACKS > SETUP.

Alarms: Set anchor drag, arrival, proximity alarms in MENU > SETUP > ALARMS.

DGPS: Connect compatible beacon receiver to NMEA input for improved accuracy.

System Reset: MENU > SETUP > SYSTEM > RESET (clears all user data).

Care & Maintenance

Use fresh water and mild soap to clean exterior. Do not use harsh chemicals or abrasives.

Store in a cool, dry place. Periodically check mounting bracket and cable connections for corrosion or wear.

CAUTION! Do not open unit. No user-serviceable parts inside. Refer servicing to qualified personnel.

Regulatory Information

FCC Part 15: Class B digital device. Complies with Canadian ICES-003. This device complies with part 15 of the FCC Rules. Operation is subject to the condition that this device does not cause harmful interference.

Copyright © Garmin Ltd. or its subsidiaries. Garmin and the Garmin logo are trademarks of Garmin Ltd., registered in the USA and other countries.

For support, visit www.garmin.com/support or contact Garmin Product Support.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Blown fuse, loose connection	Check 12V power source and fuse; ensure cables are secure.
No satellite acquisition	Obstructed view, unit indoors	Move to open area with clear sky view; wait several minutes.
Inaccurate position	Poor satellite geometry, multipath	Ensure clear view; check for reflective surfaces nearby.
NMEA data not received	Incorrect wiring or baud rate	Verify wiring connections; ensure baud rates match on both devices.
Display is dim or blank	Contrast setting, backlight off	Adjust contrast (POWER + ROCKER up/down); turn on backlight.
Unit freezes	Software issue	Perform soft reset (disconnect power for 30 seconds).

Reset: For persistent issues, perform full reset (MENU > SETUP > SYSTEM > RESET). Note: This erases all user data.

Service: Contact Garmin Product Support or authorized service center.