Garmin GPS 155XL Install Manual

The Garmin GPS 155XL is a panel-mounted TSO-certified GPS receiver and sensor providing IFR en route, terminal, and non-precision approach capability. It features a high-resolution display, dedicated function keys, comprehensive database storage, and interfaces for navigation sources. Below are key sections for safety, installation, configuration, operation, and maintenance.

1. Features at a Glance 2. Installation Overview 3. Mounting and Wiring 4. Specifications 5. Controls and Interface 6. System Configuration 7. Database Loading 8. Operational Checks 9. Maintenance & Service 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: GPS Sensor Unit, Control Display Unit (CDU), Antenna, Interface Cables, Mounting Tray.

Feature	Description
Display	High-contrast LCD with backlighting
Database	Jeppesen NavData, includes airports, VORs, NDBs, approaches
Approval	TSO-C129a Class A1, IFR certified
Interfaces	ARINC 429, RS-232, analog course/HSI outputs
Power Input	14 or 28 VDC aircraft power
Antenna	Active GPS antenna with built-in preamplifier
Keys	Dedicated direct-access keys (NAV, WPT, FPL, etc.)
Memory	Stores 20 flight plans, 1000 user waypoints
Update Rate	Position update 1 second
Dimensions (CDU)	6.25" W x 3.25" H x 12.5" D (standard 1/2 ATR short)

Installation Overview

Unpack and verify kit contents. Plan installation location per aircraft avionics stack.

Select Mounting Location: Ensure adequate clearance, accessibility, and cooling.
Install Antenna: Mount on aircraft top skin with clear view of sky; route cable.
Mount CDU: Secure in instrument panel using provided tray and hardware.
Connect Wiring: Route power, data, and antenna cables per wiring diagram.
Secure GPS Sensor: Mount in avionics bay with proper shock mounts.

WARNING! Installation must be performed by qualified avionics technician. Ensure aircraft power is OFF during installation.

Mounting and Wiring

Detailed mounting and electrical connection procedures.

CDU Mounting: Install tray in panel cutout; secure with screws. Slide CDU into tray until it locks.
Antenna Installation: Drill mounting holes per template. Seal antenna base. Connect coaxial cable to sensor.
Power Connections: Connect red wire to aircraft bus (+14/28V). Connect black wire to ground.
Data Interfaces: Connect ARINC 429/RS-232 wires per interface requirements for HSI, CDI, or external displays.
Sensor Unit: Mount securely using shock isolators. Connect antenna, power, and data cables.

CAUTION! Use proper wire gauge and circuit protection. Follow aircraft manufacturer's guidelines for bonding and grounding.

Specifications

Model: GPS 155XL
Certification: TSO-C129a Class A1, IFR en route, terminal, and non-precision approach
Channels: 8 parallel channel receiver
Accuracy: <0.1 NM RMS en route, <0.03 NM RMS terminal, <100 ft vertical (non-precision approach)
Update Rate: 1 second
Acquisition Time: Hot start <45 seconds, cold start <2.5 minutes
Database: Jeppesen NavData, updated every 28 days
Power Requirements: 14 or 28 VDC, 1.5A max
Operating Temperature: -20°C to +55°C
Weight: CDU: 2.5 lbs, Sensor: 3.0 lbs, Antenna: 0.5 lbs

Controls and Interface

CDU Front Panel: POWER knob (off/backlight/on), Alphanumeric keypad, Dedicated function keys (NAV, WPT, FPL, etc.), Inner/Outer knobs, ENT key, CLR key.

Display Pages: NAV (default), WPT (waypoint info), FPL (flight plan), NRST (nearest airports), AUX (setup). Use inner/outer knobs to scroll and select.

Configuration: Access AUX page for system setup, interface configuration, CDI scaling, and unit preferences.

System Configuration

Initial setup after power-on.

Power On: Turn POWER knob to ON. Unit performs self-test.
Initialization: Enter aircraft approximate position (lat/lon or nearest airport identifier).
Configure Interfaces: In AUX page, set ARINC 429 labels and rates, RS-232 format for connected devices.
Set CDI Scaling: Select en route (5.0 NM) or approach (1.0 NM) sensitivity.
Set Units: Select nautical miles (NM) or statute miles (SM), feet or meters.
Set Time: UTC or local.

Tip: Save configuration changes by pressing ENT. Verify interface communication with external indicators.

Database Loading

Loading current Jeppesen NavData.

Obtain Data Card: Purchase current Jeppesen NavData card for GPS 155XL.
Power Off Unit: Ensure CDU is powered down.
Insert Card: Open card door on CDU front; insert data card firmly.
Power On: Turn unit on. It will automatically recognize and load new database.
Verify: Check database effective date on AUX > STATUS page.

WARNING! Do not remove data card during loading. Ensure database is current for IFR operations.

Operational Checks

Pre-flight and periodic verification.

Receiver Self-Test: On power-up, verify "TEST PASSED" message.
Satellite Acquisition: On NAV page, verify satellite bars and 3D NAV status.
Waypoint Entry: Enter a known airport identifier; verify correct information on WPT page.
Flight Plan: Create a simple flight plan; verify leg sequencing and course guidance.
CDI/HSI Output: Verify correct needle deflection on external indicator when selecting a course.
Database Currency: Confirm effective date is within valid period.

CAUTION! Do not use for primary navigation if any test fails. Consult maintenance.

Maintenance & Service

Routine maintenance and service recommendations.

Cleaning: Use soft, dry cloth for display and bezel. Do not use liquids or aerosols.

Connections: Periodically check antenna and cable connectors for security and corrosion.

Database Updates: Update Jeppesen NavData every 28 days for IFR operations.

CAUTION! Internal repairs must be performed by Garmin-authorized service center. No user-serviceable parts inside.

Regulatory Information

TSO-C129a: Complies with FAA Technical Standard Order for IFR GPS navigation. Installation must comply with FAA AC 20-138() and aircraft-specific STC or approval. Copyright © Garmin Ltd. or its subsidiaries. For technical support, contact Garmin Aviation Product Support at 1-800-800-1020 or visit www.garmin.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No Power	Power connection, circuit breaker	Check aircraft bus voltage; verify circuit breaker; check power and ground connections at unit.
"NO SATS" or poor acquisition	Antenna, cable, obstruction	Verify antenna installation and cable integrity; ensure clear sky view; check for RAIM outage.
Database not loading	Data card, contacts	Ensure card is inserted correctly; clean card contacts; try another known-good card.
CDI/HSI no deflection	Interface wiring, configuration	Verify ARINC/analog wiring; check AUX page interface settings; test with another source.
Display blank or dim	Backlight, power	Adjust POWER knob for backlight; check internal fuse (if applicable).
Unit fails self-test	Internal fault	Cycle power. If persistent, unit requires service by authorized center.

Reset: Power cycle unit. For persistent issues, consult maintenance manual.

Service: Garmin Aviation Product Support: 1-800-800-1020; www.garmin.com