Where to start: non-functioning speedometer 2006 24Ve

[dakota4ce]

Also the harness for the triducer is incased in a black tube and opens up to aprox 4 wires under the dash , I dont see that in your photo.

It ends in 5 wires and an uncased ground-like wire. Its kinda camouflaged, but is right at the tip of my pointer finger in the photo--you are seeing the end of it, so it is blending into the darkness. The 5 thin wires of the transducer cable are only about 2" long outside of the cable jacket, so you are seeing all of it. I know the light is making the illusion.

[IDBoating]

I presume this is an AirMar triducer, perhaps from their DST800 series. If so, the green wire is, indeed, the speed signal from the paddlewheel (comes from a Hall effect sensor that the paddlewheel rotates near). The Hall effect sensor gets its ground reference from that bare wire that is wrapped around the brown one, and it gets its power from the red wire that is spliced to the heavier purple wire.

I would start by confirming that you see +12VDC between the small red wire and the bare shield wire. That would mean the triducer is getting power. Then, lacking a frequency counter or an oscilloscope, I would measure the voltage between the green wire and the bare shield wire. As the paddlewheel is SLOWLY rotated, you should see voltage, then none, then voltage, then none. The normal signal output on the green wire is a pulse train generated by the paddlewheel magnet passing by the Hall effect sensor. At speed, you get a pulse train - but with slow rotation I *believe* you will see switching voltages as the Hall effect sensor sees the magnetic field, then no field, etc. Caveat: I may be wrong about this; depending upon how the circuitry is set up, it may be that turning it manually isn't enough to cause an output change. That's why I recommended the air compressor earlier, but then a voltmeter won't be able to reliably indicate a pulse train.

Run this experiment and report back.

[dakota4ce]

I presume this is an AirMar triducer, perhaps from their DST800 series. If so, the green wire is, indeed, the speed signal from the paddlewheel (comes from a Hall effect sensor that the paddlewheel rotates near). The Hall effect sensor gets its ground reference from that bare wire that is wrapped around the brown one, and it gets its power from the red wire that is spliced to the heavier purple wire.

I would start by confirming that you see +12VDC between the small red wire and the bare shield wire. That would mean the triducer is getting power. Then, lacking a frequency counter or an oscilloscope, I would measure the voltage between the green wire and the bare shield wire. As the paddlewheel is SLOWLY rotated, you should see voltage, then none, then voltage, then none. The normal signal output on the green wire is a pulse train generated by the paddlewheel magnet passing by the Hall effect sensor. At speed, you get a pulse train - but with slow rotation I *believe* you will see switching voltages as the Hall effect sensor sees the magnetic field, then no field, etc. Caveat: I may be wrong about this; depending upon how the circuitry is set up, it may be that turning it manually isn't enough to cause an output change. That's why I recommended the air compressor earlier, but then a voltmeter won't be able to reliably indicate a pulse train.

Run this experiment and report back.

I will run it! Tomorrow after school I can send my son under the boat to be the rotator.

[IDBoating]

Remember to have him rotate it slowly. I haven't checked but it probably puts out two pulses per rotation. If he spins it too fast you might miss the voltage changes on a digital meter. Do something like "Rotate until one of the little paddles is pointing down. OK, now rotate it 90 degrees until the very next one is pointing down. OK, repeat. OK, repeat."

[dakota4ce]

Perfect. Thank you, even he I think can hang with me on this one.

Remember to have him rotate it slowly. I haven't checked but it probably puts out two pulses per rotation. If he spins it too fast you might miss the voltage changes on a digital meter. Do something like "Rotate until one of the little paddles is pointing down. OK, now rotate it 90 degrees until the very next one is pointing down. OK, repeat. OK, repeat."

[dom w. forte]

You should be able to contact Faria guages and they will get you a schematic which shows where each wire goes, they are a good company to work with , very helpful.

[ericinmich]

Remember to have him rotate it slowly. I haven't checked but it probably puts out two pulses per rotation. If he spins it too fast you might miss the voltage changes on a digital meter. Do something like "Rotate until one of the little paddles is pointing down. OK, now rotate it 90 degrees until the very next one is pointing down. OK, repeat. OK, repeat."

I don't know the specifics of the paddle wheel sensor but based on my knowledge of automotive sensors, I think that the wheel needs to be moving for it to put out any signal. It's likely a Hall Effect sensor, basically a magnet and winding with 2 wires coming out. When the magnet moves towards the winding a voltage is created and as it goes away the opposite signal is created. The faster it moves, the larger the sine wave (peak to peak voltage). If you just move it a bit an hold it, no voltage will show up on a DVM.

Another indication is that if it's a 2 wire sensor (usually twisted) , it has to be a Hall Effect sensor as described above. For it to be a true position sensor where voltage will be present as you move & hold it, it needs 3 wires, V+, ground and signal.

FYI, you should be able to put a DVM on A/C, hook the leads up to the twisted pair, spin the wheel and see voltage if all is working.

[IDBoating]

I don't know the specifics of the paddle wheel sensor but based on my knowledge of automotive sensors, I think that the wheel needs to be moving for it to put out any signal. It's likely a Hall Effect sensor, basically a magnet and winding with 2 wires coming out.

Agreed, I mentioned it might not work. But researching AirMar's products they speak of a PCB assembly in the triducer, which makes me hope that the leads aren't directly off of the Hall effect sensor but that there is some buffering circuitry. Most companies use integrated Hall sensors these days, and those chips have buffering built in. You get a digital signal out based on the presence or absence of a magnetic field, not the *change* of flux.

As for the AC range on a DMM, that's why I recommended that they use an air compressor to spin it at a reasonable velocity. We don't know the input characteristics of his DMM so we don't know how much averaging he'll get applied to that pulse train. If he doesn't spin it fast enough the signal may be hard to distinguish from noise.

[dakota4ce]

I need to sign up for am automotive and mechanical electricity course at the local community college--you guys amaze me. The multimeter I own does me very little good as my electrical knowledge is lacking. I feel inadequate! I will nevertheless check this. Football ran too late tonight and my son is in bed. We will try tomorrow!

[IDBoating]

Boat ownership spans a wide range of careers and professions. The particular problem you're addressing in this thread is attracting the attention of people whose skills are in this area. Others will chime in on other subjects. The cool part is that almost everyone here is willing to help, share their knowledge, and do it with a smile. It's a great community.

[dakota4ce]

Have you gone to the back of the speedo guage and back tracked the green wire to make sure you are on the right trail because I have not ever seen any splices splices on the green wire.

Update--the green wire from the Triducer appears to be spliced for this reason:
1. One half of the splice goes to the speedometer, and matches according to the schematic I obtained from Faria.
2. The other half of the splice appears to go "south" in the harness and ends up in the same loom as the SpeedSet wiring. I can only assume my SpeedSet panel also uses the raw Triducer signal to capture and hold speed?

For some odd reason, the gauge of the wire changes dramatically after this splice. It looks really odd and cobbled up, but looks like it was factory installed. So darned odd.

[dakota4ce]

Also, just to confirm, the ONLY way to test triducer signal is to use a multimeter on the green wire to see if I am getting a signal?

In other words, if I manually (or with a hose) spin the paddlewheel with key on, I WILL NOT see the speedometer climb as if the boat is underway?

If the above sentence is true, why does that not work? As you can tell, I just want to see that needle climb.

Note: the prior owner AND a third party mechanic both told me it worked before purchase. I then carefully examined a running video from them and could barely notice that it was NOT functioning in the video. Gee thanks, guys! Shame on me for believing them.

[IDBoating]

Also, just to confirm, the ONLY way to test triducer signal is to use a multimeter on the green wire to see if I am getting a signal? In other words, if I manually (or with a hose) spin the paddlewheel with key on, I WILL NOT see the speedometer climb as if the boat is underway?

No, spinning it with a hose should work. I worry that doing it with a finger may not work reliably, since the speed will be all over the place. But a hose should do it.

As mentioned earlier, be sure to confirm that the unit is getting +12VDC too. Then I'd worry about the output signal. Keep in mind that the speedo itself may be the culprit, which is why I suggested examining the SIGNAL at the green wire. Lack of gauge movement does not automatically mean the triducer is the problem.

[dakota4ce]

Okay, roger all of that. I will check power and also keep in mind the gauge may be the problem. Thank you!

No, spinning it with a hose should work. I worry that doing it with a finger may not work reliably, since the speed will be all over the place. But a hose should do it.

As mentioned earlier, be sure to confirm that the unit is getting +12VDC too. Then I'd worry about the output signal. Keep in mind that the speedo itself may be the culprit, which is why I suggested examining the SIGNAL at the green wire. Lack of gauge movement does not automatically mean the triducer is the problem.

[dakota4ce]

Remember to have him rotate it slowly. I haven't checked but it probably puts out two pulses per rotation. If he spins it too fast you might miss the voltage changes on a digital meter. Do something like "Rotate until one of the little paddles is pointing down. OK, now rotate it 90 degrees until the very next one is pointing down. OK, repeat. OK, repeat."

Okay, so I think this worked. I had my son slowly rotate the wheel, one paddle at a time, while I held the multimeter on Voltage across the green and twisted bare ground wire. It seemed to me that there were definitely positions where the voltage read approx 15-16, then positions where the voltage read zero or near zero. It seemed to be that once per revolution it would drop to zero, and that for 3/4 of the revolution it would read 15-16.

Does this seem feasible to you all and does it possibly suggest gauge failure? It seems to point to that.