faultfinding atillerpilot with multi meter

[LittleSister]

Quite likely dodgy connection or corrosion at the socket or where the cable from it connect to the switch/fuse/12v supply, or a partially broken cable somewhere in between.

If you have no joy with a little more dabbling with the meter, I suggest simply replace with new the cable from the supply to the autohelm socket. That will eliminate the cable itself and make you look properly at the connections either end.

Don't skimp on the thickness of the supply cable. I don't know the max current draw of the Simrad, but it's several amps and any resistance (e.g. from bad connection or undersized cable) will drop the voltage when the tiller pilot is working hard (but not when you just put a multimeter on it when its at rest!).

 

[steve yates]

I suspect corrosion at the socket as I have left the cover off before when do king and not realised for a week or so when going back to the boat!
The cable is 2.5mm twin and was installed in 2019, I only made the connections to the switch panel last year, they should be all good, properly crimped and heat shrunk etc.
The plug is an old one I had in a box.

 

[steve yates]

Finaly got round to removing the socket and discovered one of the wires loose. Bit unusual to get a loose wire in both plug and socket, but its all sorted now and bethfran has an autopilot again. Thanks all for your help and suggestions.