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  1. #1
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    Sportster speed sensor x3!.

    Hi all, just wondering if any of you electrical wizards could help me with an issue i'm having with my 2003 sportster.It is the first Harley i have owned and i have had it three years and in the time of ownership i have fitted three speed sensors they just seem like to fail annually.
    When they fail i check the continuity with a multimeter, the three wire multiplug in the wiring loom is good and the 'red' has 12volts the ' black is a good earth and when you flick the white across an earh the speedo will read a speed depending on how quick you flick so to speak, so i know the wiring is ok to the speedo
    Everytime i put a new sensor in it works fine for a few months and the it fails, when i remove it there is nothing on the sensor tip ie 'metal fillings or swarf'to alter the air gap it's as clean as the day I fitted it.
    As you can imagine this issue is getting frustating and not too say very expensive at around £65 per sensor!.
    So if anyone can shed some light or offer some advice,it would be much appreciated.
    Thanks for looking at my post and ride safe!.
    Cheers Al.

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    bluenose-1956 (04-23-2017)

  3. #2
    Senior Member bluenose-1956's Avatar
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    Hello Al,

    A warm welcome to the Harley Forums UK from Calderdale in West Yorkshire.

    I'm sorry, I'm no electrical wizard, maybe one of our other members will be able to help you with your sensor problem.

    I'm more into mechanical things myself.

    Best Regards,

    Dave.

  4. #3
    Senior Member K9F's Avatar
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    Have you still got the old sensors? You could try fitting one of the two old sensors to double check? Could the wiring be intermittent?

    When and if you buy a replacement continuity check it and see the resistance value of the new one before you fit it. Once you have a good set of readings you could check the old ones as a comparison to see if in fact they have failed.

    If you have been buying OEM ones part number 74402-95 and they have been continually failing buy an alternative to see if it fairs any better? Drag Specialities do one, although advertised as unavailable by Hogparts in the first link below they are available from Hogparts via E-Bay it seems on the second link? Your dealer will have Drag Specialities catalogue and a direct hot-line to them to check for next availability or further alternatives if they themselves don't have any which I seriously doubt.

    https://www.hogparts.co.uk/products/...nt=32210227850

    http://www.ebay.co.uk/itm/Replacemen...oAAOSwImRYD8Sj
    Last edited by K9F; 04-23-2017 at 09:33 PM.

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  5. #4
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    Unfortunately I don't have any of the old sensors because after fitting replacements the speedo worked straight away.
    I suppose I'll just have to bite the bullet and buy yet another sensor.
    I was also wondering if maybe the voltage regulator could possibly "spiking" causing the sensor windings to burn out or am clutching at straws?.

  6. #5
    New Member
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    2003 FXDL 100th Anniversary
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    Quote Originally Posted by Alsimms View Post
    Hi all, just wondering if any of you electrical wizards could help me with an issue i'm having with my 2003 sportster.It is the first Harley i have owned and i have had it three years and in the time of ownership i have fitted three speed sensors they just seem like to fail annually.
    When they fail i check the continuity with a multimeter, the three wire multiplug in the wiring loom is good and the 'red' has 12volts the ' black is a good earth and when you flick the white across an earh the speedo will read a speed depending on how quick you flick so to speak, so i know the wiring is ok to the speedo
    Everytime i put a new sensor in it works fine for a few months and the it fails, when i remove it there is nothing on the sensor tip ie 'metal fillings or swarf'to alter the air gap it's as clean as the day I fitted it.
    As you can imagine this issue is getting frustating and not too say very expensive at around £65 per sensor!.
    So if anyone can shed some light or offer some advice,it would be much appreciated.
    Thanks for looking at my post and ride safe!.
    Cheers Al.
    Hi Alsimms, I am an electronic engineer so I have some idea what's going on, or at least could be. The sensor is, I believe, what's known as an open collector hall effect type. These require voltage to power them (note this is 5V, NOT 12V, and GND) and the third wire is the output. What's happening is that as the teeth on the gear move past the sensor, an electronic switch inside is pulling the sensor wire to ground - you already have an inkling of this because your post makes that clear. The sensors themselves are quite reliable, it's usually heat that causes them to fail if anything. The only other problem would be if the sensor wire from your ECU is supplying current of any magnitude, this would stress the sensor over time and cause the sensor to fail.

    If possible, can you disconnect the wiring at the ecu and sensor ends and measure the resistance across the wires? It's possible there's a short from the power line to the sensor wire. Obviously the measurement should show open circuit but in order to ensure this you would also have to unplug the jiffy stand sensor and the twistgrip sensor as they both use the same 5V power line.

    Next thing to try is to plug everything back in except the speed sensor and measure the voltage at the speed sensor connector coming from the ECU, to ensure you do in fact have 5V and ground, and not 12V and ground. If it is 12V as you say, then that's the reason for the failure!

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