Trying to burn some music to CD-roms to play in the truck. I tested my recently burned Running Scared soundtrack to get error code 1.
Other CD's function, however my computer cannot read them. Even weirder discs I burned incorrectly many years ago work. Despite the messed up audio.
Any help is much appreciated.

A few of tips:
I don't think the 2003 supported reading MP3 disks so you are likely audio CD only.

Don't use the stick on labels. They can get warm and come off or gum up the works on your headunit.

Not sure what burning program you are using. If you are on Windows I've been using these lately:
cdrtfe Portable (cd, dvd, vcd burner) | PortableApps.com
InfraRecorder Portable (CD/DVD/ISO burner) | PortableApps.com
Though I generally have better luck with my Linux laptop (newest hardware I have with a CD drive so may be related to my windows drives being older.)

Have your burning program limit the burn speed to 1x and see if you get more reliable playback. If you get a few good burns at 1x try 2 or 4x and see if the results remain. Stay below the stated recording speed of the discs, Especially if they are older stock.

Enable buffer underrun protection in your burning program. Also when running the burn have the source data on your local harddrive (not NAS or other remote storage) and don't do anything else on the computer while the burn is running.

If you are using the "white label"/generic bulk spindles of blanks (the ones office stores, Best buy, etc used to giveaway "free with coupon" to get you in the door back when your 4Runner was new.) Try Verbatim CD-R (NOT CD-RW). If it's a mix you'll keep for a while the ones that look like old 45 single records have worked well for me.

Best Of luck getting clean burns.
Boort

Thank you, I'll try those programs when I get back. I've been using the windows media player CD burning. It's pretty out of date on win10.

From some experimenting the 03' Can read MP3 files, just super inconstantly. It's downright bizarre. some times it will return an Error 1. Other times it reads them fine, albeit very quiet. Sometimes it just spits the disc back out.

Upon even more experimenting, the 2003 can read MP3 and WAV. However it may return Error code 1.
It depends not on the disc, but how the vehicle started. If it sounds like the starter is struggling to start the car, or it's far too cold out, the CD player will return an Error 1. Unless there is already a CD in the CD deck. Then no matter what It will read the files properly.
Sometimes it may just spit the disc back out with no error code at all. I have no idea what causes this.
Lastly, officially burned CD's seem to work without flaw. Things like a bought album CD.
If it returns an Error 1 and does not want to read CD's that day, try again later. (and leave a CD in the CD port)