This Instructable will show you how to add an AUX In for your 1999 Lexus RX300. I'm not sure of the compatibility to other models or years but for the RX and the IS the instructions are very similar the only difference is the color of the wires. This Instructable can also get you in the right direction if you want to put an AUX input into your vehicle.
DISCLAIMER: I am not responsible for any damage to persons or property attempt this Instructable at your own risk!!!!
So now that that is clear lets get started.
Here is a link for a video of the final outcome of all the steps its hard to see because of the camera but it is much brighter in person. The white looks like lightning in the car at night!
Step 1: Tools and Supplies
1. Wire cutters
2. Needle Nose pliers (optional)
3. Wire Strippers
5. 10mm and 12mm wrench
6. Phillips Screwdriver
7. Small regular screwdriver.
8. Heat shrink / Electrical tape
9. Soldering Iron
10. Heat gun (if using heat shrink)
11. 3.5mm audio plug to dual RCA Cord.
Step 2: Starting the Work
First off your going to need to prepare your vehicle for service, you will want to set your parking brake and disconnect the negative of your battery.
Now that your vehicle is safe you can start to work on it, on the Lexus RX300 the CD player is located behind the glove box, to remove the glove box you need to open it and on the top corners there are 2 screws, remove these and shut the box then on the bottom there is a black plastic cover from the bottom of the box to the firewall it is attached by clips pull on it where it meets the glove box until it comes off then pull it away from the firewall to remove it, then there are 2 10mm bolts on the bottom corners of the box remove them and open the box up again, it is also held in by clips pull on the plastic around the top that forms a cover around the CD opening. The box should now be free gently lower it and remove the wire connector from it's holder on top of the box, I think it is for the airbag or seat belt light so I would not unplug it. Set the box somewhere safe as it scratches very easy.
Step 3: Remove the CD Player
Now that the glove box is removed you can get to the CD player, if you look at the picture you will see it has 2 bolts on the right side it is the same on the left there just wasn't enough room for a photo. You will want to use a 12mm wrench to remove these while removing the last bolt hold the CD Player up with your other hand, it is misleading in its appearance it is quite heavy. Gently lower it to the floor and disconnect the plug by pushing in the clip on the top of the connector and pulling, it is a pretty tight fit so it takes some pulling, then use a screwdriver to push the retainer clip from the bottom out of its holder on the back of the player. Now you can set aside the CD player.
Step 4: Wiring in the AUX
To prepare your cord you will want to cut off the RCA plugs and separate the wires a little, then strip about and inch or two off of each end where the plugs were, then it should have an insulated wire and strands wrapping around the insulated wire twist all the strands together and then strip some insulation off the inner wire and twist those strands together so now you should have 2 sets of wire coming from where the RCA Plug was for a total of 4 separate strands from the cord as seen in the picture. Now take the connector for the CD player and locate the red, black, green, and yellow wire<(white on some models). Then you have 2 options,
Option 1: Make a bare section on the wires and then make a hole in the strands to pass another wire through, the order of the wires needs to be as follows black, green, red, yellow. The bare wires of the audio cord should go to the black and red wires and the insulated wire should go to the green and yellow like the picture. Just make sure they alternate like the picture. Attach the wires by pushing them through the hole in the strands and then wrap them around the stock wires and solder connections. (WARNING: SOLDERING IN AN ENCLOSED SPACE IS VERY DANGEROUS AND THERE CAN BE FLAMMABLE MATERIALS NEARBY IN THE CAR BE CAREFUL) Then insulate them with tape or heat shrink as shown.
Option 2: Cut the wires and then twist all the wires back together in the order described above and put some solder on the connections to hold them together. Then either tape up the connections or put heat shrink over them and shrink. Then your done.
Step 5: Final Steps
Now you are almost finished take the CD player connector and reconnect it to the CD player and re-attach the retainer clip then put the CD Player back onto the bolts and tighten the nuts. Then reconnect your battery and check there are no problems, and remove the CD Magazine and remove the discs from it and re-insert it into the player it should flash Err2 on the screen this means there are no discs in the player and it will prevent the motor from spinning all the time, now connect an audio source like an Ipod and turn up the volume it should now play through the stereo. The only problem is the audio will play through the radio, CD, and tape so you just need to pause the audio to listen to the original source like the radio. If there is a disk in the player it will play the disk and the audio as well. Then I ran the audio wire though the piece of metal on the left of the glove box area. Then just put the glove box back into place with the wire held by the glove box plastic frame (against the center thing where the radio is) and push the clips into their connectors, then put the screws in and then the bolts and that's it, also don't forget the black plastic cover, insert it by pushing the extensions on the front into the holes on the firewall then push the clips into the bottom of the glove box.
You are now finished unless you want to move onto the next part which begins on the next step.
Step 6: Lights
If you are an owner of an RX300 you will know there are no floor lights or front lights for exiting or entering the vehicle, this will now confront that problem by putting LED lighting under the dash for the floor. This part will require cutting and possibly soldering so the same disclaimer still applies.
Step 7: Supplies
1. LED lights of your choice
2. Cat-5 or other multi-strand wire.
3. Multi-position switch (I used a rotary switch)
4. wire cutters and strippers
6. soldering iron
7.butt connectors. (red, blue, and yellow)
8. heat shrink and heat gun.
9. drill and drill bit.
10. hot glue and glue gun.
11. a coin.
12. 10mm socket wrench.
Step 8: Getting Power
The easiest way to do this is it pull the key cover off by tilting the wheel down and putting you finger behind the key cover and pull until it pops off only the cover and the black piece should come off, then remove the driver side under dash by pulling the top out where the key is and then work it out over to the door the remove the two bolts on the bottom corners they are 10mm the right is behind a cover remove it with a small regular screw driver, then on the key there is a screw on the bottom of the clear-ish piece remove that and that piece should come off, there are two wires going to it unplug the one going to the black piece and then remove the bulb from the clear piece. Now you want to cut the wires going to the bulb ONLY, leave some excess on the socket because you may need to reconnect them if you want to leave the stock light in place. Then I used speaker wire to make an extension from that to run under the dash, take the ends and strip back some insulation then twist the speaker wire onto the stock light wire, then there are 2 options...
Option 1: twist the stock light leads back onto the other wire and solder them all together and then insulate with tape or heat shrink. Then reassemble key fixture and run new wire to the bottom of the dash.
Option 2: Get an LED in your favorite color and a 470-Ohm resistor solder the resistor to the positive lead of the LED. Then you need to find which stock key ring light wire is the positive and solder the leads on accordingly then use hot glue to hold the LED in place on the plastic piece.
Step 9: Floor LEDs
Now take your LEDs and connect them to the new wire out of the dash and hot glue them into place, I glued them to the firewall and then held them so they shine in the right place then if you want you will need 3 more lights so you can put one for each seat. To do this remove the side panels on the center dash by removing the clips on the front of the panel near the dash you will see them next to the gas pedal you put a coin into the center slot and turn it so it pops out then simply pull it out and remove the panel. You will see a path between the air ducts, you can run the wires through here. Then repeat the steps for the driver side led only wire up the passenger side, then attach another wire to run to the back of the car for the rear, if you pull up on the running boards they are held in by clips and they will pull up. I then ran the wires through there and put the lights under the front seats pointing backwards. And that's it you should now have entry and exit LEDs. The switch is for if you want to add different colors to the lights you simply wire it up accordingly.
Step 10: Music
This is simply more of a fun thing rather than necessary, hooking up the lights to music. This is done with a TIP31 transistor and some simple connectors. Be sure the battery is disconnected before doing anything.
Step 11: Wiring
You will need to remove the CD player again for this, first take the TIP31 Transistor and put some leads on it that are about 6 inches long. The wiring is as follows in the picture, or here is a description, the left leg goes to either the green or yellow wire on the CD plug or the insulated wire on the audio cord, then the right leg goes to a spot on the chassis that will act as a ground, it can also be wired to the bare wires on the audio cord to make it more sensitive to audio, then the middle goes to the negative of the LEDs or the switch if using one. Then you are finished and they will thump to your music.