Clicking sound when ignition turned on

Discussion in 'Electronics' started by clivem, Sep 5, 2012.

  1. clivem

    clivem New Member

    Sep 25, 2011
    Hi there,

    I've got a clicking sounds coming from the rear right hand side of the car when I turn on the ignition. Lasts for about ten seconds.

    Garage says it's likely to be the power supply control unit, which determines which battery to charge.

    Problem is - it's 557 plus VAT to replace!!

    Anyone know if this part can be repaired or where I could source a used part? The breakers have not been much help so far :(

    Part number 230 540 1045
  2. DSM10000

    DSM10000 MB Club Veteran

    Jul 12, 2011
    Near Salisbury
    E32O CDi Sport, MX5 1.8 Sport, RR 4.2 SC
    Rather than guessing why not go a specialist witn the MB Star computer and get a proper diagnosis?
  3. Pontoneer

    Pontoneer MB Club Veteran

    Aug 19, 2002
    '99 S320 W140 ; '93 300SL-24 R129
    It should be easy enough to track the source of the noise by getting an assistant to turn the ignition on and off while you listen in the boot ( or wherever it is coming from ) .

    If the unit contains relays ( hence the clicking sound ) which control battery charging , then there will be high-ish current involved , enough to heat up solder joints and cause them to go 'dry' .

    If you have any knowledge of working on circuit boards , this will be an easy fix ( five minutes with your soldering iron ) , otherwise find a mate who can solder competently .

    There may be another fault ( such as a failed diode or voltage regulator ) , but the above is a good place to start since it costs virtually nothing .

    If not a visible dry solder joint , then get a proper diagnostic test run .

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