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Thread: Smart 450 window switch overhaul

  1. #1
    Join Date
    Nov 2007

    Smart 450 window switch overhaul

    The contacts on these switches tend to become poor over time due to build up of carbide deposits.
    There is a very easy fix which takes less than 10 minutes per switch.

    Save time by pulling on switch rocker at top and bottom using a special tool as shown (made from 1.6 mm solid wire). Gently release top and bottom catches when switch is fitted in the door. Disconnect switch from its plug.

    Rocker is removed by pushing to one side whilst prying off on opposite side. Then pry off front cover using a small flat bladed screw driver.

    Circuit board is held on by bent brass tabs and solder. Desolder to remove circuit board. There is normally no need to straighten the bent brass tabs.

    The switch contacts may be in a similar condition to these:

    Remove the two black plastic links and movable part of switch contacts. Clean contacts using a small flat bladed screw driver by gently scraping off any carbide deposit. Clean contacts and surrounding area in methylated spirit.

    Contacts have been cleaned and switch is ready for assembly.

    Apply proper non silicon based contact grease to the contacts. Silicon products should not be used in switches and switch contacts. When silicone is present between moving or vibrating contacts, they react under arcing conditions to form silicon carbide. These crystals abrade the contact surface and cause electrical breakdown.
    I recommend traditional battery pole grease since it is acid free. Special switch contact grease can be bought but will cost more than buying a new switch. Alternatively use standard lithium bearing grease - must be the clear type. Vaseline can also be used.

    The movable part of switch (upper contact leaves) are fitted by inserting at the back first, then slightly bending the leaf and inserting at front.

    Add grease semi liberally to contacts.

    Complete assembly, bend brass tabs as required and solder circuit board to one brass tab. Fit in Smart and enjoy years of trouble free motoring.
    Last edited by tolsen; 22-03-2013 at 08:31 AM.
    Drives a Smart Cdi - 65 to 85 MPG

  2. #2
    Join Date
    May 2009
    Prevention is always better than cure. Thanks for this. I'm sure many will find it useful.
    Smart car lover.

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