Autohelm S3 Possible Failure

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All - our Autohelm system consisting of a ST6001, S3/400 Course Computer and Type 2 rotary motor stopped functioning after getting more and more inaccurate (wide swings of helm). We thought it might be the rotary but when testing, the motor worked, however the clutch did not engage. We spoke with "Lee" at Raymarine today and he gave us some things to try. First was putting 12V to the clutch from another source to see if it engaged....it did. Next was testing OHMS between the blue and red from the clutch which showed 27.5 OHMS. Next was to test voltage from the clutch terminals on the S3. These show 10.5v at the connecting terminal between the clutch and clutch terminal. When removing the wires from the mid-point terminal that connect to the clutch terminals on the S3, we get 1.4v when engaging the autohelm. We are getting 12V to the S3. Can anyone suggest other tests as well? we are beginning to think the S3 is failing and hope to make sure before we go to that expense.

TIA

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum kspellman,

After disconnecting the drive unit's clutch leads from the course computer's clutch terminals and then commanding the autopilot into AUTO mode, determine the voltage level across the clutch terminals of the course computer ... in a properly functioning autopilot, this value should be slightly less than the input voltage to the autopilot course computer.