User Manual
Auto Trim Installation Manual  5  TruTrak Flight Systems 
December 2009  8300-013 Rev C 
Manual Auto Trim Switching with Auto Pilot Engaged 
Trouble Shooting 
Problem Cause Corrective Action 
Trim motor will not move 
with control pressure and 
manual trim control is 
functional 
No aircraft voltage and/or 
torque voltage to auto trim 
system 
Correct power, ground, & 
torque wiring 
Engage auto pilot before 
testing 
Trim motor will not move 
& manual trim control 
nonfunctional 
Trim sense voltage incorrect 
with auto pilot engaged 
from pitch servo pin 7 
Check 2.5 voltage at pin 3 or 4 
Voltage will increase or 
decrease with elevator 
pressure 
Trim motor only runs in 
one direction 
Auto trim motor control 
wires not connected to trim 
motor (relays). 
Auto trim motor control wires 
must be connected to the trim 
motor only. 
Trim bar briefly shows on 
autopilot display 
Auto trim controller speed 
too slow 
Rotate knob on controller 
clockwise 
Aircraft hunts up & down 
in pitch 
Auto trim controller speed 
too high 
Rotate knob on controller 
counter clockwise 










