Ducato idling too fast

Discussion in 'Motorhome Chat' started by Feltwell, Sep 18, 2016.

  1. Feltwell

    Feltwell Funster

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    One that I'm putting up as it may help someone Googling this problem in future.....

    Ducato 2.8JTD, suddenly started idling a bit faster than usual - 1000 rpm rather than usual 800-ish. A steady idle. No fault codes when I plugged my reader in, and nothing else was untowards. I was very uneasy though as this happened just after I'd changed the oil pressure switch - maybe a coincidence but had I done something to cause this whilst I was under the van?

    Turns out I had. When changing the switch, which is underneath the engine in a very tight spot, I accidentally brushed a spanner against a connection on to the alternator which gave a spark - I didn't think much of it at the time, other than "don't do that again" and that it was a bit dodgy that a live connection to the battery was that exposed.

    Anyway, trying to google the symptoms and I came across someone who had their alternator light on the dash on as well as the fast idle. No alternator light for me, but I stuck a multimeter across the battery and realized it wasn't being charged. Turns out the fuse in the bank on top of the positive battery terminal, where the lead from the alternator joins the battery, had blown - so the battery wasn't being charged.

    So, if your van is idling a bit faster than usual for no obvious reason - stick a multimeter across the battery terminals and check it's being charged. Not sure why the battery light didn't come on on my van - maybe because the alternator was still working, or the battery voltage hadn't dropped enough yet? I've a battery master that trickle charges it from the leisure battery whilst parked up, and a solar panel that keeps that topped up, so maybe that was why.

    New fuse for £1.99 off Ebay (it's not a normal blade fuse) and hopefully all will be well. Oh yes, and a rubber boot ordered to go over the connection where the positive lead joins the alternator, make sure it can't happen again!
     
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  2. Boringfrog

    Boringfrog Funster

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    How do you get to those fuses?
     
  3. Techno

    Techno Funster Life Member

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    Unclamp the battery and slide it towards you so you can get to the +ve connection cover
     
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  4. PeteH

    PeteH Funster

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    Just a thought have you checked that the "battery" light does come on at start-up?. When normally all the dash lights come on to prove they are OK?. I found the hard way that on a relatively modern vehicle one dash light not lighting is easy to miss!! and is usually a "blown" bulb or led. Ergo not warning!.

    Pete
     
  5. GWAYGWAY

    GWAYGWAY Funster

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    My first Fiesta suddenly started doing that, it was speeding up to run the Aircon, that it did not have. Had to pay a wadful to a Ford Dealer to reset the ECU. Trouble with modern vehicle is that you need the electronic gizmos to rest things.
     
  6. Boringfrog

    Boringfrog Funster

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    My leisure battery not charging and fridge not working on 12volt, could it be one of these fuses?
     
  7. PeteH

    PeteH Funster

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    Unlikely, Both will likely be on one of the "Habitation" circuits. Have you checked your Habitation Fuse Board?.

    Pete
     
  8. Boringfrog

    Boringfrog Funster

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    Yeah, all good. EBL99
     
  9. Feltwell

    Feltwell Funster

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    Yep - battery light comes on when ignition switched on, goes off when engine starts, all normal. That's what makes me think that maybe the van monitors the output at the alternator itself, rather than the battery voltage.

    I agree with Pete, unlikely if the rest of your leisure circuits such as the interior lights are working OK. It may be the point at which your converter has tapped into the van's power supply though. Easy enough to check the fuses if you've got a multimeter or continuity tester though, so worth a look. They're bolted in but you don't need to remove them to test them.

    I was suspicious of the aircon at first on my van, it has it fitted, but all was OK, revs dropped and rose as usual. Electronic gizmos can be a pain - I've just rebuilt the front brakes on my Audi due to a seized caliper, but I can't do the rear brakes. Why? Electronic parking brake - you not only need the laptop and software to tell the car to retract the brake mechanism all the way in order to change the pads, you also need a gizmo to supply power to the battery to keep it alive during the process - a trickle charger is not enough, lose power and you'll have all sorts of problems apparently. Various internet bodges to get round it but also lots of warnings that they leave the brakes out of adjustment and are dangerous. So, it's off to my friendly independent Audi specialist when they need doing....
     
  10. pappajohn

    pappajohn Funster Life Member

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    I'm surprised the revs were high on a JTD.
    The idle revs are ECU controlled partly to counteract stalling when a heavy load is first applied to the engine at idle. ...power steering pump, cold engine start up etc or a heavy electrical load....electric aircon etc.
    It should keep idle revs at a constant warm idle speed
     
  11. Sidney

    Sidney Funster

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    The title made me laugh...

    Idling too fast - great oxymoron
     
  12. Techno

    Techno Funster Life Member

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    The revs go up because the voltage at the ECU is noticeably low. Did the same on my later 3 litre, rise to 1200rpm after a minute followed by the battery warning light
    It was regulator failure on mine
     
  13. jockaneezer

    jockaneezer Funster

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    Might be the split charge relay playing up if the fuses check out ok.
     
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  14. Feltwell

    Feltwell Funster

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    New fuse in for me, all is well, on this bit of the van at least - idle speed back to normal and battery charging nicely. Phew! :)
     
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