Gen 5 Fi fault, 9 flashes, IAT sensor, any experience?

Discussion in '5th Generation 1998-2001' started by Marke, May 27, 2017.

  1. Marke

    Marke New Member

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    Hi Guys,
    I have my Fi light coming on during the last 4 or 5 rides and can see it's the IAT sensor as it 9 flashes.
    I have removed the IAT sensor and it has about 2k ohms which is within 1 - 4 k Ohms as per the book.
    It changes in resistance if you heat the sensor.
    I haven't looked much further yet but was thinking to replace it and put it back together but the sensor doesn't appear to have a problem.
    The fault was inconstant.
    Do these sensor fail partially?
    The sensor appears OK with the resistance measured but with an intermittent fault I'm not sure if these sensors never fail, or fail 100% once or fail in an intermittent way.
    Any thoughts as I consider what to do next?
    Thanks in advance. Mark.
     
  2. GreginDenver

    GreginDenver New Member

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    That sensor is a piece of solid state technology, you're right to think it would either work fine or fail completely. An intermittent fault/failure is more likely to be a problem in the wiring to the sensor or the connector plug, I would bet it's something that affects the quality of the sensor's ground path.
     
  3. OZ VFR

    OZ VFR Member

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    I agree with above. Dirty plug or cable/earth fault. However, an IAT sensor doesn't go back to earth, its a positive feed.
    Being a 99, I would check the main harness earth block, a common fault on older 5th gens.
    Do you get any other syptoms? Like clock resetting after numerous starts, FI light slightly blinking with blinkers?
     
  4. stoshmonster

    stoshmonster New Member

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    Coupla years ago I had an annoying intermittent problem with the MAP sensor on my '04 RC51 Marke. I removed the MAP sensor and carefully inspected all the wiring then performed all the voltage and continuity tests outlined in my service manual and they were all well within range.

    I flipped the MAP sensor over and inspected the metal spade terminals on the sensor itself and saw the telltale dull grey patina that indicated corrosion on the terminals. So I grabbed my trusty electrical terminal cleaner tweezers and thoroughly cleaned the spade terminals on both the sensor and wire harness connector plug. Got the tweezers from Mac Tools,part number is ET8040A.

    The tweezers are made out of stainless steel and the tips are coated with diamond dust so they're rough and gritty. To clean the terminals you simply slide the tweezers over the terminal,squeeze,and pull the tweezers out. You repeat this as many times as necessary until the terminal is nice and clean and shiny. Long story short,my RC51 has run flawlessly ever since.
     

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  5. Marke

    Marke New Member

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    Thanks for the replies, most helpful.
    I started the strip down and see the connector for the stator / RR is cooked.
    I did notice last ride my voltage light (add on) showed a high voltage once I turned the ignition off. Usually it goes to a 'low voltage' mode and flashes to simulate a theft alarm. Bit of a side note but the best $25 bucks I've spent on the precise LED voltage light.
    I'll fit another RR and solder the connections as I have a spare form the last 'episode'. It appears the connector got hot as the damage is localised to the connector.
    I have fitted LEWD headlights recently. They should draw the same power as the halogens so no difference on the electrical load. They are a fantastic improvement.
    Due to the amount of effort to get this far, I'll fit another IAT sensor either new or from the wreckers, prices depending.
    Most likely nothing wrong with it by the sounds but there's so much work to get to it out I'd rather have another one in the spot to rule it out.
    I suspect the RR wiring is the issue.
    Just starting to get to the stage with this bike (125,000 km's) where I'm thinking of something newer. The thought of breaking down 500 kms form home sounds crap!
    Maybe the same again gen 5 vfr or maybe a ST1050.
    I guess that's another discussion.
    You can see another thread I have up chasing vibrations with this bike and this bike is giving me plenty of work on the maintenance front.
    Mark.
     

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  6. Terry Smith

    Terry Smith Member

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    Marke I think your connector is living proof of the terminal corrosion that Stoshmonster is talking about (I need one of those handy cleaner tweezers!). With the high voltages passing through the RR/stator connector, any additional corrosion increases resistance, and more resistance = heat and a melted connector. That connector sort of hangs out in all the crud and water coming off the back wheel so probably not a great design feature, but corrosion will crop up anywhere there is humidity/moisture. Maybe the same thing is happening with you IAT sensor.

    I cut my RR connector out last year after seeing charge voltages dropping over time. It was looking a little heated but not burnt/melted . Once soldered up, the voltage has been rock steady at 14.2 volts.
     
  7. GreginDenver

    GreginDenver New Member

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    Good job tracking down the problem, a careful, quality fix will be permanent and worry-free for the life of the bike.
     
  8. Marke

    Marke New Member

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    I'm pleased to say all seems good. Installed a secondhand IAT sensor to be sure.
    Soldered the 3 phases to the RR and no more Fi light and 14.6V.
    Thanks for your help.
    Marke.
     
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