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voltage problem

Discussion in 'A4/S4 forum(B5 Chassis)' started by olds_kool, May 31, 2008.

  1. olds_kool
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    olds_kool Active Member

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    got a strange problem with my tdi, when you get in and turn ign on all warning lights go out as normal, followed by glow plugs light, but voltmeter will show about 10v if i then try starting straight away motor will turn slowly, but if i wait a few more seconds i can hear a relay click and volts will go to 12+v and it will turn over normally
    anyone got any ideas ?
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  2. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Maybe a bad eatrh on the engine? Mine played silly buggers when it was loose.
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  3. olds_kool
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    olds_kool Active Member

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    i think it only happens when cold, and it seems too constant (same length of time for relay to click) to be a loose earth strap, but worth a look, cars been hard to start for a while but was turning over normally, batterys charging ok and engines turning over normally once relay clicks
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  4. Jimbo.King
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    Jimbo.King Member

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    Your battery could be getting tired, the click you can here will prob be the glow plug relay, the glow plugs take quite alot of current to make them glow, hence the slow cranking speed when the plugs are glowing then relay clicks off and the starter has more current to crank it over faster.
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  5. olds_kool
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    olds_kool Active Member

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    sounds reasonable, and why it only seems to be from cold, will remove batt. and give a good charge, if that helps ill invest in a new one
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  6. Jimbo.King
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    Jimbo.King Member

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    At a guess it would only do it from cold because the battery has been stood overnight and may have deteriorated and when it’s warm you have driven it and put some extra charge into the battery.

    Also it may have a temp sensor on the engine to tell the glow plugs it’s warm and there not needed, but don’t quote me on that.

    If you charge the battery up it might be okay for a few days till it starts to deteriorate again, the battery maybe holding a good charge but the state of health maybe poor.

    It might be worth charging it up and then going to a garage to get them to test it properly before shelling out for a new one.
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  7. jcb
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    jcb Active Member

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    dead battery, mine did this exactly....exept mine was more like 4 volts!
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  8. moschino
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    moschino Member

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    Just because the Glow Plug light goes out it does not mean that there is no current going to the Glow Plugs.

    It is normal for the glow plugs to remain on after the light goes out.
    On my old Shogun I could hear 2 relays click. One clicked after the GP light went out and then the other would click about 30 seconds after the engine was running. I noticed that the lights were slightly brighter after the second click.

    You could test it by using a volt meter?

    Jim.
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  9. olds_kool
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    olds_kool Active Member

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    will check with vagcom if when relay clicks plugs actually go out, suppose light goes out when engine is ready too start rather than the moment power is removed from plugs, so does suggest i need a new battery, its about twice the size of my 1.8t batt. and probably twice the price!
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  10. moschino
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    moschino Member

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    I am currently running my 1.9 TDi 110 on a battery from a Jaguar.
    Got it from a breakers yard for £10
    Has been fine for 2 years now!
    Worth thinking about if money is an issue.
    Jim.
    #10

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