Low Reading Tacho

Discussion in 'Tech/Mech General' started by Bluestar, Jun 22, 2015.

  1. Bluestar

    Bluestar Funster

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    Cant find anything on this, just brought a 2003 Ducato based Kon-Tiki, one of the small problems I have is the Tacho is reading low, i.e. on tick over there is no movement but changing up through the gears I get a reading of 1k to 2k.
    Any ideas, head unit, sender or something else?
    Where do they take the sender signal from?

    Cheers.
     
  2. pappajohn

    pappajohn Funster Life Member

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    Diesels generally take a signal from the alternator....but modern ones may use the engine management computer.

    is it charging ok using a meter.
    above tickover it should read around 14.2v

    If thats ok it could be the head.
     
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  3. Bluestar

    Bluestar Funster

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    Thanks good place to start will get my meter out :)
     
  4. sallylillian

    sallylillian Funster Life Member

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    Bad ground?
     
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  5. Bluestar

    Bluestar Funster

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    Ok another check thank you :)
     
  6. John Laidler

    John Laidler Funster

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    Could be a sensor on the flywheel. It should be visible externally somewhere around the bell housing, or what passes for one.
     
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  7. Bluestar

    Bluestar Funster

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    Thank you,
    Yes that was part of the problem, don't know diesels much so did not know if im looking at the alternator or for a sender for a problem.
     
  8. Bluestar

    Bluestar Funster

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    Having had another look at my tacho it seems that the needle has zeroed way lower than the zero indicated on the dial, hence reading low all the way up, any ideas if this can be reset or is it a gauge fault?
     
  9. TheBig1

    TheBig1 Funster Life Member

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    the sender puts out a variable voltage to the gauge (not ecu driven as i recall on 2003) if its reading low, either the sensor is faulty or there is an earthing fault. no idea where my service manual disk is for the old models. should be still able to get a pirated copy on ebay. this will have everything you need to trace it
     
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  10. mjltigger

    mjltigger Funster

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    Needles now showing correctly when turned off can be a sign that the dash has been removed and not put back together right. With the engine off but the ignition on is it still showing below 0?
     
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  11. Stealaway

    Stealaway Funster

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    All the gauges on my 2004 Ducato started sticking. I suspect it was because I'd had a long journey with the screen demisters on flat out.
    I took them apart (quite easy - two screws I think) and carefully lubricated all the needle pivots with silicon spray.
    Sorted
     
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  12. Bluestar

    Bluestar Funster

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    Thanks for all the reply's, Yes used of dials sitting back on to a "stop" pin opp the zero position, on this dial doesn't seem to be a "stop so needle goes almost down to the 6 o'clock position with ignition off/ on, then rises with engine revs but only round to about the 8 o'clock position ?
    Guess the needle could have slipped but wondered if the dial could be zeroed electronically?
     
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