Select the replacement audio. You can obtain CD player with mp3 and WMA from Walmart for $89. The most important features are the ability to play mp3 and WMA format files burnt on a CD but also from a USB drive (thumb drive or removable hard drive). Also has an aux port for mp3 players like the iPOD. This was way better in price features than anything else out there.
These instructions were originally posted by me on http://www.wikihow.com/Update-a-Toyota-Corolla-Car-Radio.
Step 1: Preparing the wiring harness
Have shown the back of the new radio - the black set of pins is where the included black plug will go to. The free wires on the black plug provided with the new audio system will be connected to an adapter that will plug into the car wiring.
For the Toyota Corolla 1995 wagon, the wiring diagram is as shown below. Your car may differ substantially from this.
Step 2: Connecting the wires
Step 3: Removing the old radio
Use a thin blade (metal spatula) to probe approximately 2/3rd of the way up and try to pry the sides out. The metal blade will disengage the clip on each side. Took a bit of gentle effort but it did pop out. The location of these clips is just below the vents.
Lift the panel up, reach under it to carefully remove the plugs on the right hand side that connect the defroster, the clock and the hazard flasher. The plugs can be removed by squeezing a release tab on the plug and then gently pulling them apart.
Remove the radio - two pairs of screws on each side of the radio hold it in place. Remove these (and hold onto them because you will need them later on) and then slide the radio out.
Step 4: Pull out and disconnect the old radio
Step 5: Transfer the side brackets from the old radio to the new.
The walmart radio comes with multiple holes on it's side - some of which aligned with the mounting bracket. If you try to attach these, tiny metal studs on the brackets will interfere with the attachment, so grind them down with a dremel tool or file. Screw in the left bracket on the left side of the radio and the right bracket on the right.
In the images below, the black bezel has not been taken from the radio.
Step 6: Connecting the wiring harnesses
Test the plugged in radio to make sure it works and you can hear sound through the speakers. See if the radio lights (LED's come on - that is power is getting to the radio, see if you can hear sound from all 4 speakers by playing with the balance and fade knobs (that is all 4 speakers are connected correctly) and see if you can tune to FM and AM stations (confirming that the antenna is connected).