Case IH A-GNSS-108 - Display – Display/Monitor ECU: GNSS Receiver Error

The system is reporting a GNSS receiver error, meaning no GPS/GNSS position is currently available. The receiver is either not communicating with the display, is experiencing an internal fault, or is unable to calculate a position.

• MAGNUM AFS Connect
• STEIGER AFS Connect
• Optum tractors
• Patriot series sprayers

1. 1

   Check the 'Faults and Warnings' screen on the AFS Pro 1200 display for accompanying communication faults (e.g., F-GNSS-101 'No communication with GNSS receiver').

2. 2

   Verify the GNSS receiver is set to 'Installed' rather than 'Not Installed' on the 'GNSS & Guidance' card under the GNSS tab.

3. 3

   Check for electromagnetic interference from other cab electronics or two-way radios by turning them off and observing if the signal-to-noise ratio (SNR) improves.

4. 4

   Inspect the 4-pin (Power/Communication) and 12-pin (Main interface) harness connections on the back of the roof-mounted receiver for tightness and corrosion.

5. 5

   Check the LED indicators on the NAV-900 unit to verify it is receiving power and attempting to track satellites.

1. 1

   Power Cycle and Initialize

   Park the machine in an open area with a clear 360-degree view of the sky. Turn the key cycle off, wait 30 seconds, and turn it back on. Drive the vehicle forward to allow the GNSS receiver to initialize and determine its heading.

2. 2

   Harness Repair

   If the display still shows A-GNSS-108, use a multimeter to check for continuity and proper voltage at the roof harness. If the wiring harness is damaged, repair or replace the affected section (e.g., the RS-232 extension harness).

3. 3

   Receiver Replacement

   If the wiring is intact and the display is functioning properly, the GNSS receiver itself has likely failed internally.

4. 4

   Installation of New Receiver

   Unbolt the faulty receiver from the factory roof mount. Mount the replacement Vector Pro or NAV-900 receiver to the mounting plate. Reconnect the main interface and power cables. Navigate to the 'GNSS & Guidance' setup card on the AFS Pro 1200 to configure the new receiver and input any necessary RTK encryption keys or unlock codes.