An output's trim lies outside its minimum and maximum

What ArduPilot says:

• PreArm: SERVON_MIN is greater than SERVON_TRIM
• PreArm: SERVON_MAX is less than SERVON_TRIM

For every output that has a function (SERVOn_FUNCTION above 0), ArduPilot checks that SERVOn_TRIM, the neutral position, lies between SERVOn_MIN and SERVOn_MAX. The message gives the number of the output where it does not. The check has no switch of its own among the arming checks.

What to do, most likely first

1. A limit was edited by hand and crossed the trim: a servo's travel shortened, a gimbal or gripper set up.

   CheckRead the three values of the output named.

   FixMove SERVOn_TRIM inside the range, or widen the range, so that SERVOn_MIN is the smallest and SERVOn_MAX the largest of the three.

2. A motor output on DShot kept a SERVOn_MIN saved in an earlier PWM setup. On a DShot output the defaults become 1000, 2000 and a trim of 1000, but a saved 1100 stays, above the trim.

   CheckThe output named is a motor (function 33 to 40) and MOT_PWM_TYPE is 4 or more.

   FixSet that output's SERVOn_MIN to 1000, SERVOn_MAX to 2000 and SERVOn_TRIM to 1000.

3. The three values came with a parameter file from another aircraft.

   CheckParameter Compare & Migrate shows what differs from your earlier file.

   FixSet them for this aircraft; for a control surface, find its two ends and its centre again.

Parameters to look at

Where to do it:Parameter Compare & MigrateSetup & Tuning Guide