Trouble with Raymarine Auto Pilot

[Sailing Drummer]

S3 computer, ST6002 controller, Drive Type 3.

My problem is it won't hold a course for more than 15 seconds. At that point it turns in circles! There is nothing (that has changed) that is near the compass to make it do this. Also, it does the same thing when using the wind direction instead of the compass.

I have re-calibrated the compass and the deviation is only 5 degrees. The compass checks out based on RM instructions AND it is new. All the connections appear to be clean.

Any ideas?

Larry

[Frankly]

Is the drive unit still turning/ driving, and is the turn always in the same direction. A rudder not moving will almost always result in a turn one way or another.

Might want to disconnect the drive unit and connect it directly to a fused source of 12/ 24 volts and see if it will drive both directions (reverse polarity). Also the rudder position sensor is a wear unit. If you can operate a voltmeter might want to monitor the RP voltage at the connection to the AP control unit. Basically + fixed voltage (red wire), negative (black wire), and position signal ( blue or green but don't quote me on that). Should have a smoothly changing voltage between the signal and ground as the wheel turns.

[DeepFrz]

If it goes hard over then its possible that the drive motor wires are reversed.

[Calif.Ted]

What is on the display head when it starts turning ? Does the display change from showing the heading set ? No "Off Course" or "Wind Shift" warnings or something to indicate a momentary power loss ?

[sailorboy1]

Does the display show a course heading? If not the wire connections or the compass (but if they are bad the course controller probably says "no heading"?

I hate to tell you but is is almost surely the computer has gone bad since it hold a course for those 15 seconds before it goes crazy. Even if the compass was bad it would try to hold the course it was on. When I replaced mine a couple of years ago the new did that right out of the box and needed to be replaced.

I would call Raymarine!!!!!!!!!!!!!!!!!!!!!!!!!!

[DennisRyan]

I would turn off all other electrical devices - to remove any possible electrical interference.

[michaeld]

I had the same problem with an RM Wheelpilot. RM installation instructions are not clear on connection of the drive motor. If this is a new installation, reverse the blue and brown wires to the drive motor. That was my problem. I found RM tech support mostly useless. Rather than answering questions, I was continually referred to a RM authorized installer. Good luck.

[Emouchet]

+1 for the rudder position sensor.

[sailorbobdeb]

After we did a software update we had the same issue. Had to run the dockside wizard, etc. Raymarine said after an update it's necessary to redo all those steps. I can't begin to count the hours I've been on the phone with them.
Good luck!!

[BenFranklyn]

Had similar issues with an S3G Raymarine autopilot. It would just wandering off when it wanted. Was like going to the mall with my Grandfather. Tried everything including sending the computer back to the factory who said it was fine. Problem cured when we moved the flux gate compass to another location. There was some wiring close by but the unit worked well for a couple of years. For some reason something changed in either the compass or the wiring. Was surprised moving it worked but it did.

[bermudabob]

Try locking the wheel first and then turning on the auto pilot. Leave the wheel locked for about five minutes, then unlock the wheel. Works for me.

[Ndavies]

Had a similar issue on a friend's boat on a recent trip. Turned out to be a simple corroded connection at the drive. check all connections first.

[oldtomcat]

you need to do a sea calibration

otc

[sailon46]

Have the exact same unit and mine started doing the same thing twice, the first time the fluid (trans fluid A the red one) was low filled it up and auto was back on, no problem. Second time the actuator of the motor had come loose from the rudder quadrant. Before you do all the things the above sailors advised you checked those two things I mentioned.
Ernie on the Mary Jane

[Sailing Drummer]

I've tried/checked most of what's been mentioned with no luck yet. Will try the others soon. So far the rudder sensor worked - did not check with volt meter but indicator shows it working.
The drive motor is hooked up correctly because the manual adjustment turns the wheel the correct way.

Sometimes it turns to port, sometimes to starboard. No particular reason.

The display head shows the heading correctly.

Have not done a software update - probably won't!