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Electrical guides and mods

Starter Button

Add a push button starter the cheap and easy way.

Modification Details




Important

Adding a starter button does decrease your security a little but as you still have to insert
the key in the ignition and turn to position 1 before it will work, the risk is minimal.

It is of paramount importance that the smart is locked in reverse and the doors locked
using the remote fob every time you exit the vehicle. This activates the immobiliser.


Background Info

The engine starter button was made popular by cars such as the Honda S2000 and, as it is
with coveted items, they're soon copied and added to other cars. The smart is no different.


Typing 'starter button' into Ebay will bring up a host of universal kits,
all of which are perfectly usable in a smart and are very easy to fit.


Smart Starter Button History

Brabus

Apart from DIY retro-fitted third party versions, the first proper start button was released
in one of the Brabus Roadster models. The button sat in the top of the gearknob.

The key still had to be inserted into the the ignition and turned to position 1 for it to work.

It is possible to retro-fit the Brabus starter button into a lower spec Roadster and the
Fortwo/City Coupe. The SE Drive (electronic gear change box) contained all the necessary
electrics so you just have to swap them over and add the appropriate gear knob.


The drawback to this design is it's a bit poncy and the total price is astounding

MDC (Misterdotcom)

MDC soon came along with a
full ignition replacement starter button. Made from aluminium, the quality and style was good plus the two colour LED indicates what the starter unit is doing at the time. Retailing at 149 Euros, it's half the price of the Brabus system but looks better and has more to it than a switch and a relay.

I cannot recommend this system due to the severe security risk that it creates.
You don't need a key, you just disarm the immobiliser with the fob, get in and press the starter button.
Imagine if you forgot to lock your car or you accidentally pressed the unlock button as you put the keys away, anyone could get in your car and drive away.

Also this unit removes the gear stick locking device meaning you increase the chance
that your car can be rolled away or even rolled off down a hill by some idiots.

700cc And 999cc Ignition Info

The original ignition uses 3 wires to turn the car on and to turn the engine over.

All 3 of these wires come from the SAM unit which controls all of the electronic functions.
  • Red/Black from SAM plug 7, connection 3.
  • Red/Black to SAM plug 4, connection 1.
  • Grey/Blue to SAM plug 8, connection 38.

    The first wire listed is the permanent power from the battery.
    Second takes the power back to the SAM when the key is turned to position 2, this turns on all the electrical systems required to start the car plus anything left turned on previously.
    The final wire sends a voltage to the SAM unit to tell it to activate the starting procedure.



    Unlike most cars, the smart has a digital starter. On a standard car, the key has to be held in the 2 position to apply power to the starter motor. On a smart it only takes a quick turn and release. This is because the SAM/ZEE unit takes care of the starter motor switching.

    Because it is digital, there are no huge currents passing through the third wire.
    Not only does this mean the wire can be very thin, it means we don't need to use a relay.

    A relay is a method to switch high power loads with a low power switch, because the smart start up is low power, we only need to use a standard 12 volt switch.

    Fitting Our DIY Starter Button

    700cc Smart

    Let's make our own for less than £20. Firstly, get on Ebay and get a starter button.
    The hardest part of this How2 is deciding where to put the button.
    Many of the Honda S2000 style starter buttons are desiged to fit where the cigarette lighter goes, it is an option although removing the lighter socket isn't at all easy.

    One way to access the wires we need is to remove the SE Drive, although quite easy, it does involve removing the seats and using a special 5 spline security torx bit.
    If you have seat airbags or don't have the security torx bit this can be problematic.

    My solution is to access the wires elsewhere, somewhere easier.

    Essentially what we will be doing is adding a switch between a permanent live and the Grey/Blue wire going to SAM plug 8, connection 38. You don't have to take the power from the original ignition wires, you can take a fused feed from one of the aux outlets on the SAM unit.



    600cc Ignition Info

    The original ignition uses 3 wires to turn the car on and to turn the engine over.

  • Red from the battery.
  • Red/Black to an electrical distributer connection.

Grey/Blue to ZEE plug A, connection 3.

The first wire listed is the permanent power from the battery.
Second takes the power to a multi connector when the key is turned to position 2, this turns on all the electrical systems required to start the car.
The final wire sends a voltage to the ZEE unit to tell it to activate the starting procedure.



Fitting Our DIY Starter Button

600cc Smart

The idea is the same although instead of dealing with a SAM unit, we now have a ZEE unit.

What we will be doing is adding a switch between a permanent live and the Grey/Blue wire going to ZEE plug A, connection 3. You don't have to take the power from the original ignition wires, there are many permanent live wires around the car including one to the stereo.



Warning

I haven't yet tested this theory so if your car bursts into flames, it's not my fault.
It will have died in the name of science. I won't ever fit a start button so I am going 

to have to leave it up to you to let me know how you got on. I'll add info if I get it.


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