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Full Version: [DG11] ACU-400 not detected ('No Pilot' error)
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Good day.

I have recently purchased a sailboat which has a Es75 MFD, P70s Control head, EV-1 course computer and ACU-400. All these devices work perfectly except for the ACU-400 which doesnt show up on system devices - diagnostic menu. I have connected the P70s directly to the ACU-400 via backbone (powered by ACU) and spurs and still no detection. ACU shows an orange lamp, all fuses checked. Have also checked the backbone with a multimeter and there is no breaks or shorts. I neglected to check the autopilot correctly before purchasing, it has had a motor and cable swap recently.

Software versions;
P70s: 3.07
Es75: 19.03-00036
EV-1: 2.18

Appreciate any help as I am currently sailing up the Norwegian coast and could use some helm rest!
Hello SaltySeaPup,

The message you're seeing is definitely 'No Pilot'? That message means no communication with the EV1: a comms problem with the ACU should give you 'No Drive Detected' instead. I would like to make sure we chasing the right fault.

If you are sure that the ACU's STNG cable and power supply are good, and that there's no problem with its connection point into the network, and that everything else on the network talks together, then that sounds like the ACU's STNG CANbus communications chip has been damaged I'm sorry to say. In my experience that usually happens from one of the following things:
  • nearby (not direct) lightning strike or other ESD inducing a high voltage transient onto cabling
  • multiple power-supplies in the NMEA2000/STNG network

There's no rock-solid way of making sure whether this has happened: measuring the resistance between the blue and white terminals of the STNG connector of the ACU when power is not connected can sometimes show an outright failure, but the real diagnostic tools for this sort of thing are an oscilloscope and a CAN analyser which a good technical Service dealer should have, but few others I'm sorry to say.

If the CAN chip has been damaged then the ACU would need replacement: component-level repairs of conformally-coated, multi-layer, surface-mount PCBs like this aren't really practical any longer.

Regards,
Tom
Goo day, thanks for your response!

You're correct, the error is not the 'No Pilot', been disconnecting and reconnecting many times so must have gotten confused.

I suspect your diagnosis to be very much on the mark. I am able to get hold of the instruments needed to diagnose and indeed have experience replacing surface mounted components myself. Would there be any chance of conjuring up a schematic for the ACU? I am in dire need of it and there doesn't seem to be any Raymarine technicians up here - sending backwards and forwards to UK would prove to be extremely time consuming.
Greatly appreciate any assistance.

All the best.
Hi SaltyseaPup,

Thanks for the feedback,

I am afraid the schematics are not available to supply.

If you PM me I will try to find some tests that can be carried out to identify the CAN issue.

regards
Derek
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