On the way to town last summer, my Furuno auto pilot was wandering at least 30 degrees in somewhat calm seas. The heading sensor status light was blinking slowly, as it has done many times in the past without such an error in course. Since the PG500 is not always visible when I am at the helm, I don't know when the output switched to true as I have always used magnetic (or if this had anything to do with my erratic course changes). Thinking that the PG500 heading sensor was failing (this happened in the middle of my fishing season), I ordered another sensor and sent the old one in for repair. The new sensor will also not display magnetic which is the default heading. The old sensor was sent back as their was nothing wrong with it. I am using Nobeltec Navigation software. Shutting the computer down does not change a thing.
The status light of the PG500 will flash slowly when it is first turned on. (normal) The light should go SOLID after being on 3 mins. If the status light still flashes after 3 mins, then the compass is telling you it doesn't like where/or how it is mounted. The compass needs to be flat with the bow mark forward. It cannot be mounted upside down or on a wall. (unless you make a proper bracket... Like L bracket for wall mounting) The base MUST be flat. It should not be placed near big metal, power/transmission lines, speakers, or other objects that would interfere with it. It should NOT be used on metal hull boats. (Metal boats need Sat Compasses or Gyro)
The PG500 is a magnetic compass. It puts out magnetic heading by default. To get the compass to output TRUE, magnetic variation information (RMC) must be sent to the compass. It uses the magnetic variation data to help calculate TRUE. The TRUE light will be solid when it is getting what it needs. You can control what type of heading is output via its settings. (see para 3.5 of manual) If the magnetic variation data is lost, the TRUE light will flash.
If the compass has been calibrated, the AUTO light will be lit when the unit is using the calibration.
Please power on your compass, wait 3 mins and see what your compass is doing. If your status light is solid, swing the boat 360 while watching the status and ensure it says solid for the full turn. If it flashes, you got a location or mounting issue.
Hi Johnny,
I just shook my head when you said, “It should NOT be used on metal hull boats. (Metal boats need Sat Compasses or Gyro).” I had talked to a Furuno dealer who assured me that it would be fine to install the fluxgate on my steel boat. I remember him saying that the Coast Guard has them on their vessels even further north than I will be fishing. And I also talked to several techs at Furuno who did not caution me from installing the fluxgate. I guess what I should do is sell the two fluxgates that I have and purchase a Sat compass.

However, the fluxgate has worked well for several years. In the past, I have been able to pick out a mark on my navigation program and tell the auto pilot to take me there which it has, many times but no longer. Also, the heading on the pilot does not correspond with the heading on my Furuno GPS.
The fluxgate is mounted per your instructions but sits about three feet from my anchor winch. When I turned it on last Friday, the Status light was solid as well as the Auto and True lights. If you look in the operation section of the manual (at 1.1) there is a diagram that shows the second indicator light (True) will be showing True heading if it is on and Magnetic if it is off. Hmm? I was unable to take the boat out and do a 360 turn as I am replacing an engine. I did that maneuver at least five times last summer whenever the Status light would blink. One thing I will do to help with this error is move the fluxgate up on top of the pilot house away from any metal. I think six feet should be enough.
Thanks for the reply,
I remember him saying that the Coast Guard has them on their vessels
There are indeed some aluminum Coast Guard boats running a flux gate compass. (Aluminum is more forgiving but still not recommended) They spent lots of time to find a magnetic neutral location (where the metal is balanced 360 degrees). Flux gate compasses are NOT recommended for metal hull boats. It makes it very hard to detect magnetic north with all the metal. That doesn’t mean that it hasn’t been done. It does mean they are exception and not the rule. I also know of a tug boat that has elevated its flux gate up away from the boat (on a non-metal mast) to get it up away from the boat; far enough to work. We still don’t recommend it. Can you get lucky? SURE. You can spend a lot of money and aggravation getting one to work on a metal boat. The choice is yours. If you specifically ask a Furuno tech if you can use a flux gate on a metal hull boat, they will tell you the same. Techs get tons of questions all day long. They (we) get focused on what you are asking, and since we can’t see thru the phone….. You have to ask the right questions. Your dealer on the other hand, might have come to the wrong conclusion because he saw it on a coast guard boat. You might want to speak with him and see if he can’t make it up to you with a good deal on a Sat compass. Heading is even trickier when you involve an autopilot because it tends to amplify any compass error. If you had it working in the past, you might have luck again finding the” sweet spot”. The problem is any changes to the boat, normally end up changing the sweet spot and that includes cargo, tool boxes or movement of existing items. When you conduct the compass calibration the light will flash on the compass (normal) but under normal operations the status light needs to be lit solid. If the TRUE light is lit, the sentences output by the compass can still be controled by the selection chosen in the setup. (HDG, HDT, HDM)

When comparing heading of your compass/autopilot, it is best to compare it to your steering compass and COG from your GPS. COG is not valid unless you are moving 3 knots or better and might still be off from heading, if you are taking cross currents. In calm water, holding a straight course for three mins or more, all three devices should read within a degree or two of each other. The heading is the heart of the autopilot, and if it isn’t good; all bets are off. Overall a Sat compass is your solution but the cost involved normally pushes people to do what they can to get a flux gate to work. I say more power to them, but please understand the road isn’t easy.
Most all of my heading comparisons come when traveling at 7-8 knots in good weather with very little current. I might have exact course displays from my GPS and autopilot one direction and be off 10 degrees in the opposite. Had I known that the fluxgate would not have worked on a steel boat I would have purchased a satellite compass, which I will do. I am still wondering about the diagram in the manual at 1.1.
I am still wondering about the diagram in the manual at 1.1.
The compass has three outputs. 2 ea NMEA 0183 and 1 ea AD10. The diagram (attached from the manual) is exactly correct concerning the TRUE output, if you are speaking about the AD10 output. AD10 is a four wire binary type heading that has no way to "tell" the receiving device if the data is "Magnetic" or "True"; Hence the light. (so you know) The point I was trying make is when using the NMEA 0183 this light doesn’t mean you are only getting TRUE when it is lit. When lit, your AD10 port will be TRUE. When lit the data sentence being sent out via NMEA 0183 (not as cut and dry) is determined by your settings (page 12: “Setting the output sentence”) That means it can be HDG, HDM, HDT or a combo of the above settings. Yes, it is possible to have the TRUE light “ON” and only have HDM (Magnetic) selected to output. (Talking about NMEA port, not AD10) The sentence HDG (that carries both types of heading [if available]) is the default. If you want to ensure your receiving device has no choice but to use TRUE (via NMEA); I recommend setting it to ONLY output HDT (Heading TRUE). I hope that clarifies the point and the diagram. By default the heading light being lit will mean TRUE is going out for AD10 and BOTH True and Magnetic are going out via NMEA 0183. The diagram is trying to keep it in simple terms and the rest of the manual expands upon it. I just wanted to caution you, that if using the NMEA port, to ensure you know what NMEA 0183 sentence you have selected.


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This is great. I had called Furuno tech support about the True light always being on and was concerned that true heading was being output instead of Magnetic which I thought could be my problem having erratic headings and displaying different headings on my GPS and Furuno pilot display. I went on speaker phone and several times we went through the process to output magnetic but the light kept staying on. This baffled the tech "I don't think I have ever seen this problem before" (or such a similiar comment). We even went through the dockside exam and also the sea trial. I am going to print out your comments and staple them into my Furuno manual. I really need to call tech support again when on the boat and go through my settings.
Thanks for the reply.