Autopilot failure

[GeoffV]

Went to use the autopilot for the first time coming back from Portsmouth to Portland a couple of days ago on my Bav 37 2016 - nothing!

Checked the rudder reference set up all seems ok, Then fails on the rudder test.

I have the AC42N computer, RC42N rate compass, Jeffa LD12 linear drive. Fighting into the rear compartment I found a fuse which tested ok going into the drive.

So my question is what other tests can I do to pinpoint the exact failed item please.

[Yngmar]

So it's not moving the rudder when trying to? Does the clutch click when you try to engage the AP? Any sound from the drive motor? You can stick a multimeter on the drive motor and on the clutch wires to see if they're powered when you try to engage.

If there's no power, check the cables and the fuses between autopilot and drive.

[GeoffV]

It worked fine for the last 8 years but first time this year nothing.

 Thanks for the suggestions I will try those things.