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Engine will not crank over sometimes.... Not starter?

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by ian-g, Aug 9, 2018.

  1. ian-g

    ian-g New Member

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    Hi just re joined as could not reset password.. 09 cls 350 cdi. Occasionally when I turn the key to the start position it does not crank over or make any noise or click, but here is the strange thing... If I return the key to IGN ON and try again it still will NOT turn over, I can try countless times, but if I bring the key right back to off and try it will start as normal. This makes me think its not the starter motor or solenoid. Any thoughts?
     
  2. John Laidlaw

    John Laidlaw Senior Member

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    Checked battery and connections?
     
  3. mioba

    mioba Senior Member

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    Basics, get a voltmeter and check battery without load and with load to see if the battery is fit and the charging circuit works.
    Make sure connections are clean and tight and no oxidation.
    Beyond that could be a starter relay, faulty ing switch. May be worth and Indy for star.
    Cheers
     
  4. OP
    ian-g

    ian-g New Member

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    if i take the key back to off it starts fine so not battery....but if i take the key back to ignition on then it doesn't so i suspect its an electronic fault.
     
  5. brianbrian

    brianbrian Senior Member

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    Seems like ignition switch.
     
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  6. LostKiwi

    LostKiwi Senior Member

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    Is this not the protection mechanism? Once you've tried to start the car it won't allow another attempt without the key being turned off. Both the 210 andv230 do this (so does the 129 for that matter).
     
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  7. OP
    ian-g

    ian-g New Member

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    Ah thank you... that explains why I have to take it back to off.. What's your thought of it occasionally not turning over?
     
  8. LostKiwi

    LostKiwi Senior Member

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    My guess would be a bad starter relay
     
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  9. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    I wouldn't guess at anything.

    You need to check the drive authorisation path of the EIS. Doing lots of EIS switches at the moment for this kind of failure. The new EIS units still turn even with a foreign key unlike the old ones that used to lock.
     
  10. OP
    ian-g

    ian-g New Member

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    Thanks how do I go about checking it?
    I presume this needs some equipment or a specialist?
     
  11. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    An Indie or the dealer is the only route I would say, unless you find someone who has access to STAR
     
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  12. OP
    ian-g

    ian-g New Member

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    Thank you all for the help... Much appreciated.
     

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