Garmin GPS 400W Installation Manual

The Garmin GPS 400W is a panel-mounted aviation GPS/WAAS navigator designed for certified aircraft. It provides IFR-certified GPS/WAAS navigation with moving map, terrain awareness, traffic information compatibility, and flight planning capabilities. This manual covers essential information for installation, configuration, wiring, and initial setup. Below are key sections for safety, features, installation procedures, configuration, specifications, and post-installation checks.

Features at a Glance

Key components: GPS 400W unit, Remote Mount Antenna (GA 56 or compatible), Wiring Harness, Mounting Tray, Database Card, Documentation.

Installation Overview

Review all documentation before beginning. Ensure aircraft is in a safe, secure state with master power OFF.

1. Verify Kit Contents: Unit, antenna, wiring harness, mounting hardware, documentation.
2. Plan Mounting Location: Ensure proper clearance, accessibility, and compliance with aircraft STC or AML.
3. Prepare Panel: Cut opening per template (included).
4. Route Cables: Plan paths avoiding interference with controls, existing wiring, and sources of heat.
5. Connect Antenna: Install in approved location with clear view of sky.

WARNING! Installation must be performed by qualified personnel in accordance with applicable regulations. Ensure all wiring is secure and properly shielded.

Mounting & Physical Installation

Install the mounting tray and secure the GPS 400W unit.

1. Position Template: Use the provided template to mark the cutout on the instrument panel.
2. Cut Panel Opening: Deburr edges after cutting.
3. Install Mounting Tray: Secure tray from behind the panel using provided hardware.
4. Insert Unit: Slide the GPS 400W into the tray until it clicks into place. Secure with retention screws.
5. Check Clearance: Ensure full range of knob operation and no interference with adjacent equipment.

CAUTION! Do not force the unit into the tray. Ensure the panel cutout is clean and free of obstructions.

Electrical Wiring & Connections

Connect the main wiring harness to aircraft power, ground, and interfaced systems.

1. Identify Harness Connectors: Main power/avionics bus, serial ports, audio, external annunciator.
2. Connect Power: Red wire to aircraft bus (14/28V DC). Black wire to aircraft ground. Install appropriate circuit breaker (typically 5A).
3. Connect Serial Ports: Configure per interface requirements (autopilot, HSI, etc.). Refer to pinout table.
4. Connect Audio Lines: To audio panel for voice alerts and COM audio muting.
5. Secure and Bundle Wires: Use tie-wraps. Provide strain relief. Ensure no sharp bends.

Tip: Use shielded twisted-pair wire for all serial data lines. Connect shield to ground at one end only.

Antenna Installation

Install the remote-mount GPS antenna (GA 56 or equivalent).

1. Select Location: Top of fuselage or vertical stabilizer with unobstructed view of sky. Refer to STC for approved locations.
2. Prepare Mounting Surface: Clean and prepare for adhesive or screw mounting (per antenna type).
3. Route Antenna Cable: From antenna to unit location. Avoid running parallel to high-power wires or COM antenna cables.
4. Connect to Unit: Attach antenna cable to the ANT connector on the rear of the GPS 400W.
5. Seal Installation: Apply appropriate sealant around antenna base to prevent moisture ingress.

WARNING! Antenna placement is critical for performance. Ensure it is outside of propeller arc and not shaded by aircraft structure during typical attitudes.

Configuration & Initial Setup

Power on the unit and perform initial configuration.

1. Apply Power: Turn on aircraft master and avionics bus.
2. Unit Boot: The GPS 400W will perform self-test and acquire satellite signals (may take several minutes).
3. Enter Setup Mode: Press and hold the CLR button during power-up or navigate via the MENU.
4. Configure Interfaces: Set serial port baud rates and protocols (e.g., ARINC 429, NMEA) to match connected equipment.
5. Load Navigation Database: Insert current Jeppesen or Garmin NavData card.
6. Set System Options: Configure units (nm/km), north reference (True/Mag), terrain and traffic settings.
7. Perform Sensor Tests: Verify GPS accuracy, internal integrity tests.

CAUTION! Do not attempt flight until configuration is complete and all tests pass. Verify database is current and valid.

Specifications

• Model: GPS 400W (WAAS-enabled).
• Power Input: 14 or 28V DC, 5A max.
• GPS Receiver: 12-channel, WAAS/EGNOS capable.
• Database Capacity: Jeppesen NavData (worldwide).
• Display: 4-inch diagonal, 256-color LCD.
• Interface: 4 ARINC 429 ports, 2 RS-232 serial ports.
• Audio Output: For terrain, traffic, and system alerts.
• Antenna Input: TNC connector for active antenna.
• Operating Temp: -20°C to +55°C.
• Certification: TSO-C146a, TSO-C129a, IFR enroute & approach.

Interface & Pinouts

Primary connector pin assignments (refer to wiring diagram for full details).

Main Power & Avionics Connector: Pin 1 - Power (+14/28V), Pin 2 - Ground, Pin 3 - Audio In, Pin 4 - Audio Out, Pin 5 - COM Key Line.

Serial Port 1 (ARINC 429 In/Out): For connection to HSI, CDI, or autopilot flight director.

Serial Port 2 (RS-232): Configurable for traffic (TAS/TCAS), weather datalink, or external control.

Discrete Inputs/Outputs: Altitude input, annunciator output, terrain inhibit.

Post-Installation Testing

Perform comprehensive operational tests before flight.

1. Power-Up Test: Verify normal boot sequence and satellite acquisition.
2. Display Test: Check all pixels, backlight, and dimming function.
3. Button & Knob Test: Verify all front-panel controls respond correctly.
4. Interface Test: Verify data exchange with autopilot, HSI, and audio panel.
5. GPS Navigation Test: Enter a direct-to waypoint and verify correct course guidance.
6. Terrain & Traffic Test: Verify alerting functions (if systems installed).
7. Database Verification: Confirm current database is loaded and active.
8. Final Inspection: Secure all hardware, stow wiring, and close panels.

Tip: Document all test results and configuration settings in the aircraft maintenance log.

Regulatory & Compliance

This unit complies with FAA TSO-C146a (WAAS GPS) and TSO-C129a. Installation must be approved via STC, Field Approval, or as a Minor Alteration per FAA AC 43.13-1B. The installer is responsible for ensuring compliance with all applicable airworthiness directives and regulations. For technical support, contact Garmin Aviation Support or refer to the approved installation manual supplement for your specific aircraft.

Troubleshooting

Reset: For persistent issues, a full system reset can be performed via the Configuration Menu (note: erases user settings).

Service: Contact Garmin Aviation Product Support or an authorized Garmin dealer for repair.