Turn The ESP Off
OK, not exactly turn it off because it just ignores the wheel rotation sensors. The ABS and lateral moment sensor still works so it's a lot safer than using a trust plug.
Limitations To This Modification
This will only work on a 700cc manufactured before May 2005 as it seems as though smart
updated the ESP controller. Originally it was just used as it was from the Roadster. With the
Roadster cancelled it made more sense to have a cheaper cut down unit for the fortwo only.
This doesn't mean that there is not an ESP off pin, it is just not known yet.
If you do fit this mod it is only for getting out of snow and spinning the wheels etc.
Going over about 20mph makes the ESP automatically turn back on.
Applying the brake can also turn the ESP back on.
How Does This Mod Work?
This diagram shows how the circuit works.
The ESP module monitors pin 27, when the momentary switch is pressed, pin 27 is earthed.
This negative pulldown latches a transistor inside the module turning off the ESP.
Pressing the button again latches the transistor once more turning the ESP back on.
The ESP unit actually has the option to be disabled in the Roadster
but the single wire needed to do that just isn't available in the For2.
This single wire can easily be added to retro-fit the ESP off switch to the Pre-May 2005 700cc
For2 and even the 800cc CDi but geographical location and year varies for the diesel.
Most CDi's got ESP in 2004 but some areas didn't have them shipped there until 2005.
If you have a SAM unit for a fuse box instead of a ZEE unit, you have ESP.
What Is A Momentary Switch?
Imagine the switch that the horn uses, it only connects when you push it.
As soon as you let go, the connection is broken. Any momentary switch will work.
Why Do This Mod?
Because there are times when the ESP doesn't know best.
Apart from clowning around in empty snow filled car parks, there are sensible
reasons as to why turning the ESP off would help. Here is the one that I discovered.
My drive is only on a slight slope but it took 10 minutes to get up it into the garage.
As soon as the wheels slipped, the ESP cut the power, you need the wheel spin to eat
through the snow and ice to reach the road below it.
Where Does The Wire Go?
The wire goes from the ESP unit connection 27 to a momentary switch,
the other side of the switch is earthed.
Where Is The ESP Unit?
It's located under the car, hidden by the undertray. On a RHD smart it is located just
behind the battery box as can be seen by the pic below, this shows the mounting bracket.
Theory Is One Thing, Will It Work?
Yeah it certainly does, in late November 2006 I did temporarily earth out connection
27 on the ESP after jacking the car up and prodding the ESP unit with an off cut of wire.
Not scientific but it showed it worked. Wiring into the cabin is
very simple and there are a multitude of earth points to join to.
Fitting And Wiring The ESP Switch
Lower the front under tray, jack up the car and secure with chogs and axle stands.
Locate the ESP module, it is at the back on the nearside of the car.
The module is bolted directly to the ABS pump.
You need to crawl under the car get a good look at the wiring connection,
it plugs into the top of the module. To unhook this connection you need to
grasp the slide near you (circled in red) and pull. It will move a bit, now feel
over the top of the connection and you will feel a lever (circled in blue),
pull this back and the connector will be free of the ESP module.
To open the plug, you need to insert a knife into the back of each side and unclip it.
With that done on boths sides, the top hinges open and comes off.
You now have to locate hole 27 (circled in red).
Hole 27 should have no terminal or wire in it but it will have a rubber bung in it
Take a cocktail stick and push it into the plug so it pushes the rubber bung out.
Keep the bung.
Adding The Missing Wire
You will need a wire of at least 0.35 in size, aproximately 2 meters long with
a micro terminal on the end. If in doubt I can make and sell this wire to you.
Take the small rubber bung that was removed earlier and,
using the cocktail stick, make a hole all the way through it.
Thread the bung onto the wire so it is about 2 inches from the micro terminal.
Pay close attention to which way the terminal should be inserted,
it will only clip in one way, don't force it, you will eventually hear a light click.
Push the bung as much as you can into the hole.
Replace the plug cover, swing it over and clip it in place.
Push the connector back onto the ESP module, press down and swing the lever
back towards you while pushing the slide all the way in.
Use a few zip ties to bundle the new wire with the existing ones.
Run the new cable into the battery box through one of the three rubber bungs.
Remove the passenger footwell block and pull the new wire into the cabin.
Replace the polystyrene block and put the carpet back down.
Use a flat screwdriver to lever out the cover underneath the handbrake lever.
This is the plug that is removed.
Undo the torx screw underneath it, remove the gear knob by pulling it off
(don't push the auto button if you have one) and lift the entire cover out.
Use the flat blade screwdriver to remove the cover disc on the appropriate side.
Run the wire under the carpet and along side the gear stick.
You now also need to run a wire from an earth to the same place.
There are plenty of earth points around the car.
Replace the surround and fix down, thread the wire through the available hole.
If you want the switch to be lit up you also need to run a lighting live wire to the same
place, the easiest place to pick this up is the lighting input on the back of the stereo.
This is the switch that I will be adding, it is standard fitment in a Roadster.
You can probably get them separately from smart if you ask them.
Firstly I needed to work out a suitable place to put the switch. It came to me in the end.
Smart do a special surround for the cabrio roof button which attaches to the gear selector
housing. The surround takes a small amount of modifying to make the switch fit.
To remove the original switch you press the black tabs in each side...
And pull the switch out.
The switch carrier should be removed by pressing in the tabs either side and sliding out.
Here we have the 3 components, we only need the surround for this mod.
You may just be able to see that the ESP switch is slightly larger than the roof switch
that we are replacing. Although the roof switch is angled, the ESP switch will look ok.
You need to use a file to open the hole up slightly.
The wiring on the two switches is totally different although the switch could be used.
As you can see with the original switch in, the hole needs to be 1mm wider at each side and 2mm longer top and bottom. Keep offering up the ESP switch to judge how much to remove.
When the switch sits in nicely, glue it in place with something strong.
Try not to get glue on the rocker part of the switch.
My one is glued in for a right hand drive smart, if you have a left hand drive, make sure you
have the switch in the other way up. The surround can only be fixed to the passenger side
of the gear stick surround due to the seat base on the drivers side being in the way.
Here is is, the glue has set and the switch is in place. I have to admit I got a bit of glue
on the rocker part of the switch which has made it harder to press, but thinking about it,
that might be a good thing as it won't be accidentally pressed.
Wiring The Switch
This shows the connector used on the Roadster, it pushes into the back of the switch.
This connector isn't necessary, you can use spade connections or wire to the switch.
The connections are as follows.
1- Lighting live
2- Wire from ESP module
4- Not connected
5- Not connected
Connect up all the necessary wires to the switch and twist the switch housing into place.
Reassemble the car and get ready to test.
Turn the car ignition to the on position, ensure the dash lights go out except for
the handbrake light. Start the car. Press the ESP button and a triangle should
illuminate on the dashboard, press the switch again and the triangle should turn off.
As long as the light comes and goes when the switch is pressed, the job is done.
What Do I Do If I Have A Cabrio?
Very simple, you just attach the switch into a cabrio roof switch surround
but the other way around so it can be used on the other side of the SE drive.
James Rand completed this How2 and sent me a picture of the finished result.
You will probably find that the switch surround will need trimming
otherwise it may foul the seat runners and not have room to fit properly.
All in all, it is a very easy mod, it just looks complicated.
I will add extra pictures in due course that I believe will make it easier to understand.