Garmin GFC 500 Maintenance Manual page 26

"Open/High". With the AP DISC/TRIM INT switch depressed, the line should
read "LOW". If it does not, troubleshoot the wiring.
5.2.2 Electric Trim (if installed)
5.2.2.1 Electric Trim Does Not Run
If the Electric Trim does not run, the following troubleshooting steps may be used to help identify
the cause.
1. Check for loose terminals on the circuit breaker connections on the power wire(s)
causing intermittent power connections. Also, check for intermittent circuit breakers.
2. Check that all connectors are fully seated, and that the jack screw connectors are fully
tightened on both sides of all connectors.
3. Check the security of harness attachments. If the harness is able to move around during
flight, the wires could pull on or vibrate the connector, causing intermittent connections.
4. Check the wiring harness for faults, defects, or shorts to ground.
5. Check that the TRIM switch wiring is correct.
a. Restart the G5 ADI in configuration mode.
b. Navigate to the Flight Controls page group.
c. Navigate to the "Pitch Trim" page.
d. Scroll down to the "Trim Input" line. With the trim switch not depressed, the line
should read "-". With the trim switch pressed in the NOSE DOWN direction, the line
should read "Nose Down". With the trim switch pressed in the NOSE UP direction,
the line should read "Nose Up".
6. Check that the trim servo motor and clutch operate.
a. Restart the G5 ADI in configuration mode.
b. Navigate to the Flight Controls page group.
c. Navigate to the "Pitch Trim" page.
d. Scroll down to the "Test Trim Movement" line and select it.
e. On the following screen, select either "Nose Up" or "Nose Down". While the knob is
held in, the trim servo clutch should engage and the trim servo should drive.
f. Verify that the trim servo is installed and rigged per the aircraft-specific Install Manual
Addendum (190-02291-XX).
g. Verify that the aircraft trim system is rigged in accordance with the applicable Aircraft
Maintenance Manual (AMM), Shop Manual, or Service Manual, as applicable.
5.2.2.2 Electric Trim Speed Run Time Out of Range
If the Electric Trim Speed Run Time is outside of the range specified on the model-specific
Install Manual Addendum (190-02291-XX), the following troubleshooting steps may be used to
help identify the cause.
1. Verify that the GFC 500 system is configured as shown on the model-specific Install
Manual Addendum (190-02291-XX)
2. Verify that the trim servo is installed as shown on the model-specific Install Manual
Addendum (190-02291-XX)
GFC 500 Autopilot with ESP Part 23 AML STC Maintenance Manual
190-02291-01
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Revision 1