Garmin GTN 6 series Maintenance Manual page 111

7.4.3.2.2 Two GTNs/One SN3308
1. Remove power from GTN #2 by opening up the circuit breaker.
2. Cycle power to GTN #1 and acknowledge the prompts until it gets to the Instrument Panel Self-
Test page (see Section 6.1.1).
3. Select GPS1 as the navigation source by pressing the NAV key on the SN3308. Verify that GPS1 is
displayed on the SN3308.
4. Ensure that the SN3308 is receiving valid heading. The Vertical Deviation Indication will not be
displayed unless the SN3308 is receiving valid heading.
5. While GTN #1 is displaying the Instrument Panel Self-Test page, verify that the SN3308 is
displaying the following data from GPS1.
 Course Deviation: Half-scale left deviation, TO indication, flag pulled
 Vertical Deviation: Half-scale up deviation, flag pulled
 Active Waypoint: GARMN
6. On GTN #1 verify that an OBS value is displayed (and not dashed out).
7. Acknowledge the self test on GTN #1 by touching the Continue key.
8. Select VLOC on GTN #1 and verify that the SN3308 displays NAV 1 or NAV 2 (depending on
which navigation source the GTN is).
9. Using a VOR test set verify that the CDI deviation on the SN3308 is displayed correctly.
10. Remove power from GTN #1 and apply power to GTN #2. Acknowledge the prompts until the
Instrument Panel Self-Test page is displayed. See Section 6.1.1. Select GPS2 by pressing the NAV
key on the SN3308.
Repeat steps 5 through 9 with the second GTN.
190-01007-A1
Rev. 6
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Page 7-15