If you need a new radio because "this isn't the 50's anymore grandma" then this 'ible is for you!
Step 1: Tools and What You'll Need
The tools and other stuff you're going to need are:
-Phillips head screwdriver
-Flat head screwdriver
-2002 Toyota Corolla
-Heat shrink or electrical tape
-Aftermarket radio wiring harness adapter for 2002 Toyota Corolla (I suggest Scosche...they're customer support rocks!)
-Heat source if using heat shrink (lighter, hair dryer set on hot)
-solder and soldering iron
*YOU DO NOT NEED THE RADIO INSTALL KIT IF IT IS THE BASIC RADIO WITH CASSETTE PLAYER. YOU JUST NEED THE WIRING HARNESS.
*KEEP YOUR RECEIPTS AS THEY WILL BE NEEDED FOR ANY RETURNS.
*+*DISCONNECT THE NEGATIVE BATTERY TERMINAL JUST TO BE SAFE*+*
Step 2: Removing Trim
So, right away, these next few pictures have watermarks because I got them from online as I didn't think to do an instructable until about halfway through. (the site in the watermark is a good resource if I wasn't clear enough or you have more questions or whatever the case may be)
*+*THE TRIM PIECE I AM REFERRING TO IS THE OUTER (square-ish/circle-ish) LINE AROUND THE SECTION CONTAINING THE RADIO, VENTS, CLOCK, HAZARD BUTTON, AND EMPTY SPOT IN THE PICTURE*+*
There are approximately 6-8 clips holding the trim piece in place so work the flat tip screwdriver all the way around the edge of the trim gently pushing in the clips and prying away the trim piece.
*Be careful! The last thing you want to do is leave a hefty battle scar in the dash, it hurts resale value and just looks ugly. (there's an 'ible on here about fixing dashboard scars using bondo, I think)
Step 3: Remove Screws
Great, you've made it this far! Move the trim piece out of the way like in the picture or you can completely remove it by disconnecting the cables that are connected to the back of the clock and hazard button.
There are four Phillips head screws in holding the radio in place, remove them with the Phillips head screwdriver and set them aside.
Once unmounted, unclip the OEM stock wire harness from the radio. Disconnect the antenna cable as well. (If an aftermarket radio is what you're removing, there will be another wire harness adapter attached to the OEM stock wire harness. You need to disconnect those in order to continue.)
Step 4: Remove More Screws (and Mounting Bracket)
With the disconnected radio you can now see that there are two screws on each side of the radio holding the mounting bracket in place, remove both the screws and bracket then set them aside. Do the same for the other side. You are now free to do as you wish with the old stock radio, it is no longer needed.
(Take note that the brackets are labeled 'LEFT' and 'RIGHT' or 'L' and 'R' as you will be remounting them on the new aftermarket radio later)
Mount the brackets the same way that they were on the OEM radio only this time on the aftermarket radio, on most radios the brackets (which have a small nub on one side) fall right into place on the sides they should be on and come to rest directly over the correct holes for the screws. Screw the screws in, connecting the brackets to the radio in a sturdy manner.
Step 5: Connect the Wire Harness
Take the aftermarket wire harness adapter and strip away approximately half an inch of wire coating on each wire (typically they're pre-cut so you may not have to do this part which is pretty user friendly...don't be afraid to call the customer support line)
Take the wire harness from your new radio (not the adapter...this is attached to the back of your radio and is clipped in with a bunch of wires sticking off the back) and strip away half an inch of wire coating on each wire.
Cut some of your heat shrink tubing and place it over one of the wires.
*+*When wiring the connections, make sure all wires are connected to their twin (yellow to yellow, grey with stripe to grey with stripe, purple without stripe to purple without stripe, etc.) If there are any wires that aren't used, don't panic, that just means that if it was a different car like a Ford or Geo you would have to use the extra wires but because it isn't a different car, you don't need those other wires.*+*
Twist your wires together tightly so that they do not pull apart, fold the connection parallel to one of the wires you just twisted.
Slide your heat shrink tubing over the connection completely covering it, heat and let shrink but don't burn or melt it.
OPTIONAL: If you have the skills you may choose to solder the connection, I don't because the connections wont be under too much strain from being securely mounted behind the dash.
OPTIONAL: You may choose to wrap in a lot of electrical tape as opposed to heat shrink tubing or on top of heat shrink tubing to further insulate your connections.
Step 6: Check Connections
Check your wire connections making sure all wires are connected to their twin (yellow to yellow, grey with stripe to grey with stripe, purple without stripe to purple without stripe, etc.)
If there are any wires that aren't used, don't panic, that just means that if it was a different car like a Ford or Geo you would have to use the extra wires but because it isn't a different car, you don't need those other wires. All you have to do in this case is cap them off by either cutting the wire flush with the wire coating, or using some heat shrink tubing over the end leaving it some extra tubing at the end, or wrapping it in electrical tape.
Step 7: Test Connections and Radio
This is the fun part, seeing all that hard monotonous work of wiring finally paying off!
Plug in the wire harness to the back of the aftermarket radio and connect the antenna into the back as well.
*+*Reconnect negative battery terminal*+*
Turn the car to ACC. mode (don't start the engine, no need to waste gas).
Turn on the radio, does it work?
-If yes, hurray!
-If no, check connections to antenna (make sure it's all the way in) and the wiring harness including the pairing of the wires that you should have just checked.
Try the CD player, does it work?
-If yes, rejoice at the sound of music!
-If no, check pairing connections. (You could also, if your radio has one and it wasn't the connections fault, press the reset button as per the radio's instruction manual when the car is turned to OFF)
If equipped, try the AUX-IN, does it work?
-If yes, good for you conqueror of sound waves!
-If no, check pairing connections. (If it isn't the connections then try the reset button, if that doesn't work then I have no idea, try contacting the manufacturer of both the aftermarket wire harness adapter and the aftermarket radio.)
Step 8: Install Aftermarket Radio and Trim Piece
The aftermarket radio I was originally installing had a broken board for the AUX-IN so when the radio and CD player worked but the AUX-IN didn't, I had to return it and get a different aftermarket radio and redo the entire process. (A real hassle but this is why we hang onto receipts)
Now that it's all working correctly, you can go ahead and place the aftermarket radio in the correct spot and align the mounting brackets so that the radio sits where it should. Screw the four Phillips head screws that you took out and set aside earlier back in where they go.
Reconnect the clock and hazard button wires if you chose to disconnect them earlier.
Slide the trim piece back into place and push, the clips should reclip (and make a clicking sound without too much effort.
Step 9: One Last Thing...
Do one last test and if it all works, drive off into the sunset like the BAMF you now are!