Article on: Auxilary Input on OEM Radio 

This mod adds a stereo input for to your stock WRX head unit via a cassette adapter. Some have argued that it's better to use a RF transmitter, but I felt the cassette adapter is the preferable way to go. The only problem is that the cord hanging out is ugly. This mod solves that by hiding the cable behind the face of the radio.

First, take out the cup holder by removing the two screws. Then pop off the silver molding surrounding the radio. It's held on by four clips. The plastic seems sort of flimsy though, so maybe be careful.

Then remove the six screws that are holding the head unit in place. Remove all cables from the back and side.

There is a bracket attached to each side of the radio, held on by four gold screws. Take both brackets off.

Next remove the plastic face from the metal body. Locate the line where it splits. Also locate the 8 clips around the sides, two on each side.

Remove the clips in the order shown here. You may need several screwdrivers or a stack of two dimes or whatever's needed to get it started, but once you get the first four off, the remaining should be a breeze.

Insert your cassette adapter, and locate where you'll run the wire. Cut the wire cleanly at a point where a splice will be hidden.

(at this point, you may be tempted to try to remove the rest of the metal shell. It's probably not worth it. The panels have to be taken off in a specific order, the front may be the last, and there are many many screws that need to be put back in the correct place. It's just a lot easier to simply thread the wire through from the front.)

If your cassette adapter's wire is sticking out of the side to the left like this (mine is a Sony CPA9C), you can run your wire like this.

Here, the green wire is a stiff wire (a strand of telephone wire actually) that I bent into a hook and pulled the audio cable up through this hole so I had a loop that I could use to secure the audio cable in place.

I left enough room in my cable to let the tape slide out if someone accidently presses the eject button. You need to be careful and make sure to place the cable in a spot where it won't let the mechanism jam. For this reason I didn't leave enough cable to allow the tape to come completely out and be replaced by a normal cassette, but if you're adventurous, go ahead and try it.

Since the mechanism is moving, you'll want to tie down the cable with a cable tie. I ended up leaving a lot of slack in the cable because once the plastic face is put on, a lot of the slack is taken up. Just play with the tape in all positions before tying it down.

Just to test how much room behind the face there is, I put a stack of three pennies behind the plastic face, and the face still snapped down tightly, so there is no problem with putting a small cable tie here.

The cable then emerges right behind one of the clips on the plastic face. The metal bracket needs to be filed down some to give the cable a minimal amount of room and prevent the cable from being pinched / cut by the bracket.

And here's the final result. I then put some heat shrink tube around the cable where it exits the radio to prevent the cable from being cut by any sharp metal and to ease some of the pressure there from being at a tight bend.

The cable is completely hidden behind the plastic molding, so from there you can run the cable to somewhere in the dash, inside the glove box, down the center hump and beneath the carpet, or whatever.

And other than the minor filing which won't be noticed by anyone, this mod is completely reversible in case you decide to sell your car.


(The ISDC cannot be held responsible for any modifications that adversely effect the warranty of your car.)