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Accessory wire in Garmin harness-What does it do?

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Accessory wire in Garmin harness-What does it do?

Old 10-06-2014, 07:15 PM
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Default Accessory wire in Garmin harness-What does it do?

I have a Garmin 740S and 546S and both of them have an orange wire in the main harness that the installation manuals label "Accessory On". But there is no info in the manual about what it's for and it's electrical capabilities and Garmin tech support knew nothing about it. Not what it's for, nor what it does, nor could the "expert" find out.

Does anybody know what it's for? And its capability to activate a relay or power something.

I have a NMEA2000 bus and would like to turn its power on when either of the Garmins is powered up and I'm hoping the Accessory On wire will do it.
Old 10-06-2014, 07:30 PM
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That's what it does, it's similar to the "blue" wire in car radios. You can connect it to your NMEA 2k network to turn it on when you turn on the 740s, others have suggested hooking the N2K to a separate switch in case you didn't want to run everything on the N2K but just wanted the 740 on. I've used the "accessory on" to connect to things that would only run when the GPS is on line the Radar or Autopilot things like that. How in the world could a Garmin tech not know this?

Last edited by mahimahi99; 10-06-2014 at 08:30 PM.
Old 10-06-2014, 08:13 PM
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Garmin techs are not very smart. They know nothing about their products. I called asking about hooking up a fuel flow to my 531s. They said it can not be done, I asked here and was told i needed a CANet kit. Thanks to THT I got it and everything works properly.
Don't call Garmin! Ask for help here. :-)
Old 10-07-2014, 03:24 AM
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Default GSD24 "Transducer Disconnected" failure

Just installed Garmin 8212 and GSD24. Transducer was existing B744V, and wired with Garmin adapter box. Couple of days after install, failure "Transducer disconnected. Sonar shutting down", would occur almost immediately after power up. Garmin was little use. They said check wiring, which I did while they were still on the phone. No issues there, with exception that he told me there is a misprint showing a bare wire going to terminal four. Removed wire and nothing. So now I'm being god transducer is bad. Shut unit down for an hour, and sounder reappears for few minutes. Hmmmm. Anybody had or heard of this issue? Upgraded all software and left the boat for an hour. When I came back, sounder worked like a champ rest of day!
Old 10-07-2014, 03:25 AM
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Oops. Posted in wrong spot.
Old 10-07-2014, 06:10 AM
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thats the tickle or wake up wire
Old 10-07-2014, 06:14 AM
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Originally Posted by BoemarineBrian View Post
thats the tickle or wake up wire
OK. So what does it do? Apply power or ground to turn the Accessory On? Do you have any details? What does Garmin intend it to be used for?
Old 10-07-2014, 09:43 AM
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Its used to turn on other items used in conjunction with the Garmin unit, n2k radar radio/ amps and so forth
Old 10-08-2014, 09:20 PM
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Gave up on Garmin techs today after another call so I got my meters out and went to the boat.

The "Accessory On" wire on the GPSMAP 740S is an open circuit to ground whenever the unit is turned off and after the software boots on power up it is pulled to ground through a 1.5K ohm resistor. It has a diode from the input to ground with the cathode of the diode on the input and the anode on ground.

I couldn't determine the current capacity for the circuit but with a 1.5K resistor in series with the signal, that will limit max current into the input of roughly 10 milliamperes max at 12-14v or 20 milliamps @ 24-28v. Obviously meant for signaling more than relay activation but usable for power switching with a high sensitivity relay coil or suitable solid state circuit.

I'm going to use it to switch power on for my NMEA2000 bus via a transistor circuit whenever the 740S or 546S are turned on.

Last edited by colecaz; 10-09-2014 at 05:41 AM. Reason: Arithmetic error
Old 10-10-2014, 11:03 AM
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The NMEA2K bus draws very little current. My NMEA2K is powered from the engine key switches, either one with diode isolation and also a toggle switch if I need the NMEA2K on with engines off, as using the chart plotter and NMEA2K GPS antennas with engines off. So my NMEA2K is only on when engines are running or if I need it on when engines off, not very often do I need that. So I have no need to worry about NMEA2K tiny currents at all.

Curious why you need to turn NMEA2K on with the Chart plotter, that means every time you want the NMEA2K network on you need the chart plotter on? Remember if you need GPS position data for the VHF, and the VHF radio is NMEA2K for an emergency call with position data, your chart plotter has to be on and working? If your chart plotter is sending NMEA0183 GPS information to the VHF than that of course does not apply.



Jim
Old 10-10-2014, 08:03 PM
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jfwireless:

My N2K bus is powered like yours, switched by the engine key switches. I have two chartplotter/sounders and a compass on it. Garmin 546s and 740s plus Lowrance Point-1 compass. They are spec'd at up to 0.1 Amp ea or 0.3A total load from the N2K bus power. I want the bus on when either Garmin is on to get vessel heading during drift fishing so I can have orientation vs nearby waypoints. Also the 546s sends depth to the 740s via N2K. I have the 740s sounder function disabled to prevent transducer interference. I primarily use the 740s chartplotter function and the 546s depth function but keep their unused capability available for backup.

My 740s and Standard GX2150 VHF communicate via NMEA0183 high speed bus for DSC and AIS data so the N2K isn't a factor there.

So I want the power to the N2K to be automatically on only when needed, not via a manual override switch that can be left on and enable a potentially constant 0.3A battery drain. The "Accessory On" wires of the Garmin units let me do that by controlling an external power switching transistor circuit of my own design.

Last edited by colecaz; 10-11-2014 at 06:25 AM.
Old 05-21-2016, 09:32 AM
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I inquired about the wire on the GPSMAP 527xs. Garmin's reply:

"The orange wire is used to turn on accessories networked to the chart plotter via NMEA 0183. When the unit is turned on it will signal the accessory to turn on. It is 24 AWG wire and it can be extended by using the appropriate gauge wiring for the distance of the run.

It’s a ground signal, when the unit turns on it closes the ground, completing the circuit and telling the unit to turn on. No Voltage carries through."

I wired a Digital Yacht ANT200 AIS receiver to the 527xs via NMEA 0183 connecting the orange wire to the ANT200 ground and the ANT200 NMEA Out (-). Not working. Thinking the NMEA Out (-) has to go to actual black (-) on the Garmin. Can someone confirm please?

Last edited by scchang; 05-21-2016 at 09:46 AM.
Old 05-21-2016, 03:59 PM
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The old garmin nmea183 GPS antennas had an orange wire. (As well as power and ground) And probably the old sounders too. So when you turn on the plotter it will turn on the accessorys. Same as the yellow wire on all the current simrad / bng stuff. But it's +12v. The current garmin stuff does it using the network cables.

I would not run any current through it. But you could probably use it to trigger a relay. Put 12v to one side of coil. And other side to orange wire on plotter.
Old 05-21-2016, 04:04 PM
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Originally Posted by scchang View Post

I wired a Digital Yacht ANT200 AIS receiver to the 527xs via NMEA 0183 connecting the orange wire to the ANT200 ground and the ANT200 NMEA Out (-). Not working. Thinking the NMEA Out (-) has to go to actual black (-) on the Garmin. Can someone confirm please?
What?... Connect ais to own power. connect nema 183 wires together from both units. You don't use the garmin orange wire

A lot of the garmin products use the neg as the 183 ground
Old 05-21-2016, 09:11 PM
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Thanks.

I thought I could use the orange Accessory On wire to power on the AIS with the chart plotter. Next, I foolishly thought I could run the 0183 (-) to the orange wire since it is a ground (of sorts). So, initially I had the AIS ground and the AIS 0183 Talker B connected to the orange wire and the AIS didn't work. Following smac999's advice, I revised the connections.

Just to make sure I have this correct, the wiring is as follows:

Garmin 527xs:

Red - Power
Black - Ground (power and NMEA 0183)
Blue - NMEA 0183 internal port 1 Tx (out)
Brown - NMEA 0183 internal port 1 Rx (in)
Gray - NMEA 0183 internal port 2 Tx (out)
Violet - NMEA 0183 internal port 2 Rx (in)
Orange - Accessory on
Yellow - Alarm low

Digital Yacht ANT200 AIS Receiver:

Red - Power
Black - Ground
Gray - NMEA Out +
Brown - NMEA Out -
Yellow - NMEA In +
Green - NMEA In -

New and Improved Connections:

1. Both devices Red and Black to battery + and -
2. ANT200 Gray NMEA Out + to 527xs Brown NMEA 0183 internal port 1 Rx (in)
3. ANT200 Brown NMEA Out - to battery -

Look okay?
Old 05-22-2016, 11:34 AM
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Originally Posted by scchang View Post
Thanks.

I thought I could use the orange Accessory On wire to power on the AIS with the chart plotter. Next, I foolishly thought I could run the 0183 (-) to the orange wire since it is a ground (of sorts). So, initially I had the AIS ground and the AIS 0183 Talker B connected to the orange wire and the AIS didn't work. Following smac999's advice, I revised the connections.

Just to make sure I have this correct, the wiring is as follows:

Garmin 527xs:

Red - Power
Black - Ground (power and NMEA 0183)
Blue - NMEA 0183 internal port 1 Tx (out)
Brown - NMEA 0183 internal port 1 Rx (in)
Gray - NMEA 0183 internal port 2 Tx (out)
Violet - NMEA 0183 internal port 2 Rx (in)
Orange - Accessory on
Yellow - Alarm low

Digital Yacht ANT200 AIS Receiver:

Red - Power
Black - Ground
Gray - NMEA Out +
Brown - NMEA Out -
Yellow - NMEA In +
Green - NMEA In -

New and Improved Connections:

1. Both devices Red and Black to battery + and -
2. ANT200 Gray NMEA Out + to 527xs Brown NMEA 0183 internal port 1 Rx (in)
3. ANT200 Brown NMEA Out - to battery -

Look okay?
Here's what it looks like to me:

out = TX transmit
In = Rx receive


ANT200 >>> Garmin
Gray out+ >> Brown In +
Yellow In + >> Blue out +

Brown, Green, black >> black >>>>all 4 wires go to ground.

Red 12v+ Red 12v+
Old 05-23-2016, 09:20 AM
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My connections were good. It was the chartplotter baud rate that I needed to change. It was buried pretty deep in the menus IMO.

Thanks for all the help!

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