[TG] [TG11] diagnosing issue with ST4000 wheel autopilot

[laurentdubois]

Hello Tom,


- After the problem occurs and you go to Standby, in what way does the pilot act weird? Just shows 4001, or other stuff, and if so, what?
It continues to try adjusting course and randomly steer hard to starboard even though it's in standby mode (with no effect since the clutch is disengaged)


- Does the unexpected turn always happen to starboard?
Yes, always to starboard


- How do you get it working again - power cycle?
We turn it off for a while and then start it again.

Normally, when a pilot goes hard-over one way after working successfully for a time, it's either:
- broken winding in the fluxgate compass, making and breaking contact intermittently; when broken, you'll get a 'dead sector' of static heading. Next time the problem occurs, see if you can steer slow circles and watch the indicated pilot heading (on the pilot display or a repeater, e.g. chartplotter) and see whether it turns smoothly, consistently and evenly throughout - if not, your fluxgate is suspect.

From what I remember, I won't able to do this unless I first power cycle the autopilot to get it back a normal state.
Is the fluxgate component replaceable?


- a dead spot on the rudder-reference, if there is one, which is intermittently causing the pilot to think that the helm is hard port, causing it to drive starboard to correct.
There is no rudder reference in this setup.

Perhaps a video of the behaviour might help, if you can coax it to happen again at the right time.
Other than that, you can either work through the above or it might be time to consider a new pilot.
Regards,
Tom


Thanks Tom.