Fiat dipped beams not working when engine running!

Discussion in 'Tech/Mech General' started by meanders, Nov 22, 2013.

  1. meanders

    meanders Funster - Life Member Life Member

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    Hi all.

    Just spent two hours in Tesco's car park after pulling off on the way to Waldergraves because no dipped beam and it was getting dark.

    The dipped beams work perfectly with ignition on until you start the engine. They then go off after a few seconds. If you turn them on with the engine running they come on for 1 - 2 seconds then go off. Breakdown guy couldn't believe it until he tested them himself.

    Convinced the relay is OK, but really can't figure out what is going on. I rang the FIAT garage and the technician had never heard anything like it.

    Ended up driving home on sidelights with main beam when I could. Rather frightening in places.

    Anyone else had the same problem? Any clues as to where to look? Anyone at Waldergraves able to fix it?

    If not, its back to the garage next week.... More expense!
     
  2. pappajohn

    pappajohn Funster Life Member

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    main lights could be canbus controlled and a fault may exist in the canbus system.

    engine off voltage may be ok but start the engine and the volts will rise to 14v +.

    could be overloading the canbus circuit for dipped beam.

    main dealer should have the equipment to 'talk' to the canbus and retreive fault codes.
     
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  3. dogman

    dogman Read Only Funster

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    As a get you out of jail fix, take the connectors out of the 3 pin plug on the back of the bulb/unit, put the high beam cable on the dip beam connector then run on dipped beam only, better than sidelights only.
     
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  4. laneside

    laneside Funster

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    This is a long shot and no logically reason why it should work but with my Fiat I can go into menu and switch daylight running lights on and off. Pure illogic but I would try to see if it made a difference
     
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  5. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    Its very easy to misunderstand the purpose of CanBus systems and this is a case in point. The CanBus system does not carry any significant current it is simply a data channel. The idea is that instead of lots of big cables carrying high currents around a vehicle there are now just a couple and each unit (could be a light cluster or a seat adjuster or any one of a number of things) has a micro computer connected both to the CanBus (data stream) and the main power carrying cables. Micro computer A (let's say the lighting switch) sends a coded signal along the data bus (CanBus), lighting cluster micro computer recognises this coded signal as an instruction for it to do something etc, etc, etc. The CanBus cannot be "overloaded" as it never carries significant current.

    To the OP, as Fiat are notoriously poor with electrickery (almost as bad as they are with gearboxes) and 90+% of electrical problems are poor earth connections I would start with the Earth connections. The engine earth strap is a well known source of problems but mostly with the engine management systems. The vehicle contains numerous micro computers with a variety of names, one of which is often referred to as the "BSI" (Body Systems Interface) this often controls things like seat belt pre tensioners, interior lights and quite possibly the lighting systems. A poor earth on this unit might easily be the cause but it won't show up as that on a diagnostic computer, more likey it will show up as something completely unrelated.

    D.
     
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  6. meanders

    meanders Funster - Life Member Life Member

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    Thanks to you all.

    Will look in the 'menu' tomorrow although I don't remember seeing that option on our MH.

    Cross wiring is a good idea.... just not a lot of room behind the headlamp units. Also when on main beam only the innermost lens was lit. Not sure on the X250 if the outermost lens has both dip and head. If so, it wasn't working either!

    Thanks again.
     
  7. pappajohn

    pappajohn Funster Life Member

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    agreed Dave, and i could have worded it better.

    i should have said overloaded the canbus processor circuit.
     
  8. TheCaller

    TheCaller Funster

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    According to my manual, I should be able to do that too. But like meanders, I can't find it in the menu in the van. At the risk of pirating this thread, any hints on how to turn off the daylight running lights in an X250 would be gratefully received.

    As to the main topic, earthing faults do cause some very peculiar symptoms, even on pre-CanBus systems. I think that's were I'd start looking too. Never had to work on a CanBus system (yet! - only had mine a month), so can't offer any specific advice I'm afraid.
     
  9. trophychap

    trophychap Funster

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    We wold be well and truly stuck if that happened to us. We only have lights on or off on our column stalk on our new this year Pilote. Seems a bit odd really that the sidelights only operate when the ignition is switched off.

    Hope its an easy fix for you. I sometimes wonder how much technology we really need in our vehicles.
     
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  10. jhorsf

    jhorsf Read Only Funster

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  11. billkce

    billkce Funster

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    I'm not a techie by any means, but we had a similar light issue with our Merc Autotrail.

    When we indicated left, power dropped off.

    We discovered condensation inside the left indicator housing on the left wing. We dried it, put in a small silica pack and its been fine since.

    Might work.:BigGrin:
     
  12. SIFTA SAM

    SIFTA SAM Read Only Funster

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  13. rainbow chasers

    rainbow chasers Read Only Funster

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    Bad Earth - you just now need to find where that earth is. Not uncommon for battery terminal earths to get loose - some are not tightened enough due to limited space in these vehicles - pay particular attention to 'extras' that are added on, as these could cause a loose connection. Also check other earth points for fusebox, engine etc.

    BSI units are prone to issues, though usually it can be a earth point, relay or the BSI fuse that is faulty or dirty. The Voltage of your engine battery can cause issues with BSI units on HDI engined vehicles as they must be a minimum of 12v. If it is a BSI related issue, I would look at connections, and fuses/relays first before reflashing software. Most BSI issues are fairly simple.

    Check the Headlamp relay connections also, as there may be an issue of overheating caused by a dodgy relay which can give this issue,even if the relay appears to be working ok - may not be all the time.

    If you have recently, or have fitted immobilisers/tracking devices etc, do check the ignition wiring loom as well for short circuits
     
  14. tonka

    tonka Funster Life Member

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    Ref the daytime lights on/off switching... It is in the menu but it does not show if you have the engine running.. It confused me at first.. Try with ignition key in and turned but engine not started...
    Something like that anyway....
     
  15. aba

    aba

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    just a quicky have you had a headlight bulb changed recently ???

    i ask this as i had a tail light bulb fail and when i replaced it it just flashed on then went off so i swapped it to the other side and it did the same (the fault moved) i then sourced a more expensive bulb and that worked ok.

    the only thing i could put it down to was the canbus system wasnt happy with the reading of the bulb an as such decided it was faulty so shut it down.

    what happened to a switch and a big wire to the lights it either worked or didn't it was a simple battery-fuse-switch-light and as such easy to find.
    these things are getting far too intelligent and if the bulb is 48 watts instead of 50 the system says thats faulty so im not turning it on.
     
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  16. jaygee

    jaygee Funster

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    We has a similar problem a few weeks after we bought our Fiat motorhome and on our first trip out in it to Val Thorens we ended up having to tailgate Haganaps along the motorway as we lost headlights when the engine warmed up:Eeek::Eeek::Eeek: We had to ensure that our home journey was carried out in daylight.
    Anyway when we got home we found that one of our customers had bought his motorhome into our garage with the same fault. After extensive investigation an auto electrician traced the fault to the the BSI unit which controls all the light switching behind the fog light switches in the dash. This was replaced and cured his fault.
    So we took our van to the same auto electrician and he confirmed it was the same unit on our van that was faulty so we had it replaced and we haven't had a problem since then (2 years ago).
    I think the whole job cost about £295 but that was not done at a main dealer it was an independent electrician.
    I'm not saying that this is your fault but just that it may be worth investigating this unit?
    Jacky
     
    Last edited: Nov 23, 2013
  17. laneside

    laneside Funster

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    Just had a thought----I had better check mine we have done 13, 000 miles now and believe it or not we have never been out on the road in the dark yet
     
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  18. jhorsf

    jhorsf Read Only Funster

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  19. meanders

    meanders Funster - Life Member Life Member

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    RESOLVED.:Smile:

    After 8 days at the Fiat dealer and with support from the Fiat motorhome support line in Italy, it was finally fixed.

    It was the 'BODY COMPUTER'. After a hard reset and both keys recoded, its absolutely fine.

    They tried changing the stalk, but that made no difference. All earth straps were checked and all fine. Italy suggested the hard reboot. If that hadn't worked it would have been a new computer. :-(

    I've found four other people who have had the same problem on various forums, but no-one posted the fix, so hopefully this will help others. Not something you can fix yourselves, but at least you can push them in the right direction.

    The good news is that despite spending many hours, i was only charged the hours labour for the reprogramming. :thumb:
     
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  20. jhorsf

    jhorsf Read Only Funster

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    in the info I posted above it tells you how to reset the body computer
     
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