Garmin GDL 90 Installation Manual

Also see for GDL 90: Installation manual

LimitationsGDL 90 Installation Manual 560-1049-00 Rev B 5-15 TROUBLESHOOTINGThis section provides information to assist troubleshooting if problems occur after completing theinstallation. Use Table 5-1 and flowcharts in Appendix B to assist in troubleshooting. A PC connected tothe GDL 90 Maintenance port is essential in troubleshooting. In addition, devices connected to the GDL90, such as a control panel / transponder or MX20 can be useful for determining whether the GDL 90 isfunctioning properly or if there are problems with the installation.5.1 TROUBLESHOOTING PROCEDURETable 5-1. Troubleshooting GuideProblem Possible Cause SolutionNo LED activity 1. No power to unit. 1. Verify that power and ground leads arecorrect and power is getting to unit.No targets aredisplayed on yourMX20 MFD.1. No targets are transmittingADSB.2. No targets are within line-of-sight range.3. Antennas and cables are notconnected.4. MX20 is not connected.1. Verify that other targets are transmittingADSB.2. Verify that other targets are within line-of-sight range.3. Verify that antennas and cables are connectedproperly.4. Verify Ext LED is not lit.Your aircraft is notdisplayed on otheraircraft MFD.1. Transmit malfunction. 1. Verify that Tx LED on the GDL 90 blinks atlease once per second.Tx LED is not on(flashing at 1 Hz rate).1. Unit is not transmitting UATmessages.1. Verify antennas and cables are properlyconnected.Rx LED is not on. 1. Unit is not receiving UATmessages.1. Verify antennas and cables are properlyconnected and that other UAT-equippedaircraft is transmitting.Maint LED is on. 1. Maintenance check may beneeded.1. Use the Service command in Maintenancemode to verify system condition. Consultdealer or factory technician for recommendedaction.Ext LED is on. 1. External system(s) orconnections to those systemshave failed.1. Use the External command in Maintenancemode to determine which system(s) orconnection(s) has failed. Verify wiring,connector and health status of the failedsystem(s).GPS LED is not on. 1. System or GPS failure 1. Use the Service command in Maintenancemode to verify system condition. If theStatus LED is also lit, return unit to Factoryfor repair.Status LED is on. 1. System malfunction or failure 1. Return unit to Factory for repair. Refer toSection 5.2 for procedure to follow.