READ THIS FIRST:
I do not assume any liability or responsibility for any unwanted results that occur from doing this modification. Precautions must be taken because you are dealing with one of your car’s safety features, the SRS / Airbag. If you do not feel that you can safely do this modification, then don’t do it. Read ALL directions before even attempting to start this project.
Here is how you install a 2004 USDM STi steering wheel on a 2002-2003 WRX.
This installation retains factory cruise control, horn, and SRS. It is also completely reversible if you do not cut the parts off of your WRX steering wheel.
Start by removing your old steering wheel.
Start by disconnecting the negative terminal on the battery. Wait about 5 minutes and then step on the brake a few times. Make sure the tires are facing forwards and the steering wheel is straight. Next, loosen the Torx bolts. There is one on each side of the steering wheel shroud. They are located at 3:00 and 9:00. The screws will back out, but remain in the shroud. Now you can wiggle out the air bag.
To remove the airbag, you must push down on the yellow tab and slide the green piece all of the way over. Once the airbag is removed, set it aside, and you will be looking at this.
After the airbag is off, take a 17mm socket and a breaker bar and break the steering nut loose. It is best if you have someone hold the steering wheel while you break the nut loose. Once the nut is loose, unscrew it a little bit, but leave it on. This will allow you to tug on the steering wheel and not worry about it flying off into your face. Once the wheel breaks loose, remove the nut and steering wheel.
Getting the necessary parts off of the WRX steering wheel
We need to start by getting the cruise control switch off of the WRX steering wheel. To do this, remove the two Torx screw on the bracket on the right side.
Unplug the plug for the cruise control at the bottom and the spade for the horn. Remove the switch and the bracket.
Here is the WRX cruise control switch out of the wheel. You will need to remove it from the bracket by removing the two phillips head screws.
Set all of this aside and get your STi steering wheel.