DIY Retrofit O.E. Audio Steering Wheel Controls
Since I got prodded by another member here, I thought I’d do my bit and post up some info on how I added audio control buttons to my ’14 ST. The install was relatively easy and should be simple for anyone who can read a basic wiring diagram. The most difficult part is removing the airbag. Although this is described in detail in the ESM, and I’m sure a lot of us know how to do it, I’ll add that in for the sake of completeness.
My car have cruise control standard. The audio switch came from a breakers yard from a car that had only audio controls and no cruise. There might be some wiring differences on the steering wheel, depending on what was factory fitted on the car but it seems like the so-called “clock spring” (the thing on the steering column that allows you to rotate the wheel without screwing up the wiring), is pretty much the same for all GU’s, at least Series IV onwards.
Step1 – Prep the switch: The pic below shows the switch.
1.
![01-Audio SW.jpg]()
On my setup, I removed the red wire completely as this was not required. The reason will become clear a little later. There are a number of ways you can do this wiring. Depending on how anal you are (I wrote the book), you need to remove ALL the terminals inside the connector with the red wire WITHOUT DAMAGING THEM. If you can’t figure out how to do this, ask an auto electrician or someone who installs In-Car Entertainment systems. They’ll pop them out in a few seconds.
Step2 – Prep the car: Disconnect the battery and leave the car sit for at least 5 mins. As you will be working with the airbag, rather be safe than sorry.
Step3 – Disconnecting the airbag: Using a small flat blade screw driver, carefully pop the two little plastic covers either side of the steering wheel. This will expose the two tamper proof T30 Torx screws which you need to remove. Word of advice; if you don’t have a tamper proof T30 Torx bit, GO BUY ONE. Don’t try using something else. You’ll just end up damaging the screws which are critical for correct airbag operation. I bought a set of bits from Bunnings for ~$20. Well worth it.
2.
![02-T30 Torx.jpg]()
Once you’ve removed the screws, carefully lift the airbag off the steering wheel. There are two connectors you need to disconnect. The one is for the switches (white), the other (small yellow and black one) is the airbag. Using a small flat blade screw driver, carefully raise the black clip ~2mm off the yellow connector, then pull the connector off the airbag. The black plastic clip is a retainer. You’ll break the connector if you do not lift the clip first.
In the pic below you can see the black clip in its raised position.
3.
![03-ABag Before.jpg]()
Also, the blue wire in the white connector is the 12V supply for the horn. The red wire that I removed from the switch, performs the same function, which is why it’s not required.
Step4 - Wiring: Remove the 2 Phillips head screws holding the switch blank in place on the LHS of the steering wheel. You can use the same screws to attach the audio switches to the steering wheel. I got the screws with the switch, so I had extras.
Following the same process, remove the Cruise Control switch on the RHS from the steering wheel, unclip the white connector from its retainer on the airbag and disconnect the blue wire for the horn. This will make wiring it up easier as you won’t have to work on the airbag unit.
The next pic shows the end result of what I did.
4.
![04-ABag After.jpg]()
Comparing this to the previous “before” pic, you can see:
1. Splice the two green wires together (one from the audio switch and the other from the cruise control switch).
2. Add the blue and orange wires from the audio switch to the connector from the cruise control. (Make sure you get the order correct.) The cruise control connector is identical to the one that came with the audio switches, so the terminals will simply click into place IF you didn’t damage them during the removal process. The order should be:
Orange (AUDIO SW)
BLUE (AUDIO SW)
YELLOW (CRUISE SW)
GREEN (AUDIO & CRUISE)
BLUE (HORN)
Step5 – Installation: Using the Original screws, reinstall the Cruise Control and Audio Switches, reconnect the blue horn wire and clip the white connector into its retainer.
Reconnect the airbag to the steering wheel by connecting the white connector and the yellow airbag connector. Make sure you push the black clip back onto the yellow connector once attached to the airbag. The black clip is what actually makes or breaks the electrical connections, so if this is not pushed down, you WILL have an airbag light come on.
Refit the airbag and install the T30 Torx screws. Torque them up to 10Nm. The ESM says to replace these. I didn’t. If they’re not damaged during removal, you don’t really need to replace them. Finally, pop the two plastic covers back in and you’re done on the wheel.
5.
![05-End-Result.jpg]()
Step6 – Audio Unit: The aftermarket unit I installed has a “learning” function for steering wheel controls and uses 3 wires. I suspect this configuration is fairly common for aftermarket audio units with this capability. The wires are marked “Steering Wheel Control 1”, “Steering Wheel Control 2” and “Steering Wheel Ground”.
The OE audio connector on the car (M192) is shown in the two pics below. This connector has the three wires. STRG SW A (Purple Pin6), STRG SW B (Light Green Pin16) and STRG SW GND (Black Pin15). I connected 1 to A, 2 to B and Ground to Ground.
6.
![06-M192-Top w-Labels.jpg]()
7.
![07-M192-Btm w-Labels.jpg]()
Finally, reconnect the battery.
And that, in a nutshell, is it. I couldn’t have done this without the wiring diagrams in the ESM and spent a fair bit of time studying these before I attempted this mod, so I’d suggest anyone who wants to tackle this to do the same. It will help, especially if your car does not have cruise control as the airbag wiring might be different.
Since I got prodded by another member here, I thought I’d do my bit and post up some info on how I added audio control buttons to my ’14 ST. The install was relatively easy and should be simple for anyone who can read a basic wiring diagram. The most difficult part is removing the airbag. Although this is described in detail in the ESM, and I’m sure a lot of us know how to do it, I’ll add that in for the sake of completeness.
My car have cruise control standard. The audio switch came from a breakers yard from a car that had only audio controls and no cruise. There might be some wiring differences on the steering wheel, depending on what was factory fitted on the car but it seems like the so-called “clock spring” (the thing on the steering column that allows you to rotate the wheel without screwing up the wiring), is pretty much the same for all GU’s, at least Series IV onwards.
Step1 – Prep the switch: The pic below shows the switch.
1.
On my setup, I removed the red wire completely as this was not required. The reason will become clear a little later. There are a number of ways you can do this wiring. Depending on how anal you are (I wrote the book), you need to remove ALL the terminals inside the connector with the red wire WITHOUT DAMAGING THEM. If you can’t figure out how to do this, ask an auto electrician or someone who installs In-Car Entertainment systems. They’ll pop them out in a few seconds.
Step2 – Prep the car: Disconnect the battery and leave the car sit for at least 5 mins. As you will be working with the airbag, rather be safe than sorry.
Step3 – Disconnecting the airbag: Using a small flat blade screw driver, carefully pop the two little plastic covers either side of the steering wheel. This will expose the two tamper proof T30 Torx screws which you need to remove. Word of advice; if you don’t have a tamper proof T30 Torx bit, GO BUY ONE. Don’t try using something else. You’ll just end up damaging the screws which are critical for correct airbag operation. I bought a set of bits from Bunnings for ~$20. Well worth it.
2.
Once you’ve removed the screws, carefully lift the airbag off the steering wheel. There are two connectors you need to disconnect. The one is for the switches (white), the other (small yellow and black one) is the airbag. Using a small flat blade screw driver, carefully raise the black clip ~2mm off the yellow connector, then pull the connector off the airbag. The black plastic clip is a retainer. You’ll break the connector if you do not lift the clip first.
In the pic below you can see the black clip in its raised position.
3.
Also, the blue wire in the white connector is the 12V supply for the horn. The red wire that I removed from the switch, performs the same function, which is why it’s not required.
Step4 - Wiring: Remove the 2 Phillips head screws holding the switch blank in place on the LHS of the steering wheel. You can use the same screws to attach the audio switches to the steering wheel. I got the screws with the switch, so I had extras.
Following the same process, remove the Cruise Control switch on the RHS from the steering wheel, unclip the white connector from its retainer on the airbag and disconnect the blue wire for the horn. This will make wiring it up easier as you won’t have to work on the airbag unit.
The next pic shows the end result of what I did.
4.
Comparing this to the previous “before” pic, you can see:
1. Splice the two green wires together (one from the audio switch and the other from the cruise control switch).
2. Add the blue and orange wires from the audio switch to the connector from the cruise control. (Make sure you get the order correct.) The cruise control connector is identical to the one that came with the audio switches, so the terminals will simply click into place IF you didn’t damage them during the removal process. The order should be:
Orange (AUDIO SW)
BLUE (AUDIO SW)
YELLOW (CRUISE SW)
GREEN (AUDIO & CRUISE)
BLUE (HORN)
Step5 – Installation: Using the Original screws, reinstall the Cruise Control and Audio Switches, reconnect the blue horn wire and clip the white connector into its retainer.
Reconnect the airbag to the steering wheel by connecting the white connector and the yellow airbag connector. Make sure you push the black clip back onto the yellow connector once attached to the airbag. The black clip is what actually makes or breaks the electrical connections, so if this is not pushed down, you WILL have an airbag light come on.
Refit the airbag and install the T30 Torx screws. Torque them up to 10Nm. The ESM says to replace these. I didn’t. If they’re not damaged during removal, you don’t really need to replace them. Finally, pop the two plastic covers back in and you’re done on the wheel.
5.
Step6 – Audio Unit: The aftermarket unit I installed has a “learning” function for steering wheel controls and uses 3 wires. I suspect this configuration is fairly common for aftermarket audio units with this capability. The wires are marked “Steering Wheel Control 1”, “Steering Wheel Control 2” and “Steering Wheel Ground”.
The OE audio connector on the car (M192) is shown in the two pics below. This connector has the three wires. STRG SW A (Purple Pin6), STRG SW B (Light Green Pin16) and STRG SW GND (Black Pin15). I connected 1 to A, 2 to B and Ground to Ground.
6.
7.
Finally, reconnect the battery.
And that, in a nutshell, is it. I couldn’t have done this without the wiring diagrams in the ESM and spent a fair bit of time studying these before I attempted this mod, so I’d suggest anyone who wants to tackle this to do the same. It will help, especially if your car does not have cruise control as the airbag wiring might be different.
