Wiring Autotrim

[SMO]

I have an EFIS AP IV with the Autotrim module. Looking at the wiring instruction in the EFIS installation manual, it says to power the Autotrim from the AP Master switch. Because the pitch trim motor is powered from the Autotrim module, it appears there is no way to isolate the trim motor from the servos, they either both have power or none has power.

This would mean that any time I turn off the AP master switch I lose my pitch trim. Is this correct?

[TrutrakTech]

No, you won't loose the trim. When the autotrim is disengaged, a relay inside closes and simply reconnects the trim motor wires together as if the autotrim wasn't even there. Any time the autotrim is engaged, your manual trim switch will do nothing, when the autotrim is disengaged, your trim will work normally.

[SMO]

The trim motor would normally get its power from the switch. In my case I am using the VP200, the switch wires run to that Control Unit and the power wires that would normally go from the Control Unit direct to the trim motor are wired instead to the auto trim. When the AP Master is on, those wires are disconnected from the trim motor (when the AP Master is off they are reconnected) using a relay internal to the auto trim. The source of power for the trim motor is then from the AP Master through the auto trim.

[TrutrakTech]

Yep! You've got it!