Tacomatrx450
Active Member
Does anyone know what kind of value the speed sensor outputs to the mpem/speedometer. Is it a voltage if so how much? I am currently trying to fix the sensor cause I dont want to pay 65 for a replacement :"/
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sea doo speed sensor problem
- Thread starter Tacomatrx450
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BMANN06
Well-Known Member
I don't think (in the 2 stroke world) that the speedo sensor actually goes through MPEM. I believe you have a sending unit (wheel/tube etc) that is connected to speedometer. Personally, I wouldn't bother with replacing it or fixing it, even if you bought a new one, it won't be accurate worth a crap anyways.
Tacomatrx450
Active Member
Yea figured :/ I actually replaced the gauge with a tach but I hate seeing a unworking part on my sea doo .. best bet would probably be going with a aftermarket setup
BMANN06
Well-Known Member
Hear yah there!! You could just start with continuity test between your sending unit and harness that plugs into speedo?
Tacomatrx450
Active Member
I checked and it does have a small voltage when measuring at the hood harness, when I spin the sensor wheel but its very small. could it be the wheel itself ?
BMANN06
Well-Known Member
Could be, check the cable itself for any cracks or cuts. Then if you have a compressor have the someone blow some air at it with the air chuck. Then get a reading, I'll take a look at mine this weekend (i've got the wheel too, boats at the cottage) and put my multimeter on it and get some readings (resistance/voltage etc) for you to compare with.
Tacomatrx450
Active Member
Sweet thanks greatly appreciate it!
Tacomatrx450
Active Member
Think I got it, to test the speedo I flickered the signal cable on the negative end of that battery.. the speedometer itself supplys about 10v to the signal cable..the sensor is basically just a on off switch and the speedo reads the delay between on/off.. also the sensor runs through the mpem to the hood then connects to the gauge. I read that you can disable the speedometer through the software, but you can also just bypass this. But i am thinking that it ties into a fuse because the sensor circuit can fry if the currect exceeds its rating. Turns out my sensor is the reason its not working :/ right now I think i will just buy a 3" gauge with a pickup 
SabrToothSqrl
Well-Known Member
and that's cheaper/better? I spent $90ish replacing mine... the whole assembly... now it's 2 MPH off at 65 MPH... (vs my GPS)... i think it was worth it.
ski-d00
Well-Known Member
The sensors go bad because the potted epoxy leaks water/moisture around it and kills the electronics. I have repaired seadoo speed sensors but is not worth the time involved. The sensor is actually pretty complicated and is a Magneto-Resistive speed sensor that uses the Hall effect without switching to ground to change voltage when a magnet passes through its field. The 4 lobes of the paddle wheel are actually magnets that change the voltage output with each quarter turn. The rate of this is what determines the speed. Crankshaft and camshaft sensors work the same way using a lobe off the steel crank or cam gear.
The wheels don't go bad, they're just magnets, but they do break lobes off. If your gauge doesn't have moisture in it, most likely it's the speed sensor, they fail frequently.
The wheels don't go bad, they're just magnets, but they do break lobes off. If your gauge doesn't have moisture in it, most likely it's the speed sensor, they fail frequently.
SabrToothSqrl
Well-Known Member
mine personally failed or was broken where the sensor meets the ski hookup inside the back of the hull. the shop that shall not be named and does crap work jammed the connector in... i didn't figure this out however until i had already installed 90% of the new one... might have saved $100 on that... o well... i checked it at 10,20, 25,30, and WOT, and it's always within 1-2 MPH of my GPS. so I think, for a paddlewheel on a ski that sees more time in the air than in the water, it works just fine.
Tacomatrx450
Active Member
I had cut the wire very close to the epoxy and would not get any reading. I did find the diode and hall effect sensor while digging into the epoxy . I'm going to order these dollar parts and then fill it with jb weld and see if that works... :/ there's a few sensors on eBay but for 60 bucks but with no guarantee they will work. Looking at the stupid sensor I think its tied to ground with a diode to the mounting plate bolts and then the other wires are 10 v power n the signal output grrrrr hate this sensor
Tacomatrx450
Active Member
The wheel also has magnets placed North then south while the stupid thing turns it opens n closes the circuit. Yea I had it powered on I seen the voltage supplied by the guage signa changel wire but nothing while spinning the wheel not even a voltage/ current
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What type of GPS do you need to work on water?
Is this a hand held type device?
How does it tell you your speed?
Is this a hand held type device?
How does it tell you your speed?
SabrToothSqrl
Well-Known Member
What type of GPS do you need to work on water? - any that works.
Is this a hand held type device? - mine is
How does it tell you your speed? - with magnets.
(no, not with magnets.)
http://electronics.howstuffworks.com/gadgets/travel/gps.htm
Is this a hand held type device? - mine is
How does it tell you your speed? - with magnets.
(no, not with magnets.)
http://electronics.howstuffworks.com/gadgets/travel/gps.htm
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