BMW 1-Series Forum (F20) 135i - > Second Generation 1 Series Forum > DIY Guides and Instructions > M Buttons Sports Eco Mode Mod
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      12-31-2020, 11:07 PM   #1
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Drives: 2009 135i Low Mount ST
Join Date: May 2017
Location: ACT

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I changed my blank buttons to M buttons and made them function as the Sport and Eco mode buttons. This is not a step by step DIY but will give you a good idea how to attempt it if you want to at your own risk. This took me about a day to work out from start to finish and only cost me $30 for the genuine M buttons which I got off someone with an M2 who changed to the coloured versions. The rest of the parts I had lying around so were not at an additional cost to me.

This was done by running a harness from the switch in the centre console to the steering wheel through the clockspring. My car has a single stage airbag so only had two wires through the clockspring this means there are 4 pins not used for that particular connector.

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The blank buttons have these tabs that stops the button from being pressed in on the M buttons these are flush.

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If the airbag connector only has two wires then you can do this mod. If you have a two stage airbag this will probably have 4 wires so there will only be two spare pins you will need 3. You may be able to find another spare pin on another connector which you will need to work out what the corresponding pin/wire is on the other side of the clockspring with the use of a multimeter.

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On the connector on the back of the clockspring I used pins 1-3 the corresponding numbers on the airbag connector are 4-6. I ran a harness around the steering wheel shaft and back down and on the side of the center console up to the Sport - Eco switch.

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I had an old spare N54 wiring harness I have been hacking up for my various projects this is where I got my pin connectors and wires. If you have removed the the mobile phone unit in your car you may be able to use this connector but I can not confirm if this will actually work as I have not checked the size. So you will need to check for yourself or you will need to purchase some connectors.

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Remove the Sport and Eco switch from the centre console and pulled it apart I then soldered 2 wires B & C onto the circuit board and ran the wires out the bottom where there were already two small holes and joined to the harness I ran from the steering wheel.

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I then tapped the last wire from the harness into the brown and white wire on the connector which is A for the circuit and the common wire for the Sport and Eco switch.

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Pull the steering wheel switch apart as you can see it is missing LEDs for the M buttons you will need to solder some in and resistors for both of them.

For my M1 and M2 buttons I utilized the original switches on the circuit board this is a bit difficult and requires modifying the circuit board traces etc and unfortunate I did not take any pictures of my final version as I was too focused on getting it to work. I would not recommend this route for most people unless you know what you are doing as you can easily damage your board. Essentially you will need to isolate the M1 and M2 switches from the rest of the circuit as it will interfere with the LIN signals and make functions like speed limit go off when you don't want them too.

What I would recommend is getting some switched similar to these and just have then placed on top of the original switch with some thin wires. I drilled a hole out the back of the switch to run the 3 wires to the airbag connector.

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Ray J

Last edited by RJ019; 01-01-2021 at 12:17 AM..
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      02-03-2021, 06:24 PM   #2

Drives: BMW M135i 2014
Join Date: Nov 2020
Location: NE

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This is awesome, fair play. Do you know what the resistor and LED sizes are? Also do you know the exact colour of the original orange LEDs?
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