Lexus IS 300 CD Changer Error 1 and AUX In Mod

After years of having difficulty reading burnt CDs, my OEM CD changer finally succumbed to the infamous "ERROR 1" and simply refused to play anything at all. I used to be able to get it to play by turning it on and off but this time that didn't work either (I tried, very pissed off, for about half an hour). The car's 11 years old as of this writing (2013), so I guess it's about time.

I mainly use it as my daily driver/commuter (not calling it a beater just yet ;) these days, so I wasn't about to drop major $$$ on a new head unit. Luckily, I found this post and this post on my.is so I figured why not, it's not like I'm gonna break it any more than it already is. Glad I did, because after rougly $25 in parts and an afternoon of work, I can now play MP3s off my phone through the OEM head unit. The volume from the AUX in is a little quieter than stock but other than that, I didn't notice any difference in quality.

• 4PDT 12V DC Relay - Part number 4PRLY-12, $4.25 from All Electronics. The link in the original post on my.is is dead so here's the link if anyone needs it.
  
• Relay Socket - Not really needed but it makes connecting the wires to the relay much easier because you can just plug the relay in to the terminal and screw the wires in instead of soldering the wires directly to the relay. Part number MT14-PC, $5.50 from All Electronics.
  
• SPST Rocker Switch - Part number RS-198, $0.60 from All Electronics. No link for this one because it broke on me. So if anything, avoid this switch and get a different one.
  
• 2 RCA Y Cables - I just happened to have 2 I bought a while ago sitting around. Don't remember how much they cost but probably $2 or so. These are RCA female to 2 RCA male Y cables.
  

1. Remove the OEM head unit

   Pretty straightforward and plenty of pics in this post at my.is.

2. Locate the head unit harness
   

   
3. Cut the white, red, green and black wires
   
4. Connect the head unit harness wires to the relay socket

   I connected the head unit side to the bottom row of the relay socket (sorry, forgot the pin numbers) because I wanted the AUX-IN to be the default input. i.e., it'll use AUX-IN when there's no power to the relay.

   
5. Connect the RCA Y cables to the relay socket

   Cut both male connectors of the RCA Y cable:

   

   There's 2 wires inside the insulation of the RCA cable:

   

   The center is positive (+) and outter is negative (-). Connect them to the relay socket:

   

   F* you ERROR 1, I win!! ;)