I recently purchased a 2005 Camry LE with the 2.4L 2AZ-FE with had a few issues that needed to be addressed. The most pressing issue was the speedometer not working, which was directly related to the ABS light, brake light, rough idle, and P0500 engine code. It idled so low and rough it actually died on me while I was going slow in reverse. I searched on various forums for hours and my research indicated it was likely something with the ABS control module, ABS wheel sensors, or the speed sensor located on the transmission under the air filter box.

Early on in my research, I went ahead and purchased a cheap speed sensor to see if it would be an easy fix. When this did not solve the issue, as it often does from what I've read online, I decided to work harder on diagnosing the issue instead of throwing parts at it. I learned that ABS codes cannot be read by your typical $20 OBDII reader but require a specialized reader. To read the codes without one of these readers, you can jump pins 13 and 4 on the OBDII port and the ABS light on the dash will blink out a code. You can jump the pins with a bit of wire or an unpainted paperclip(what I used). I've attached images of the OBDII pin layout and what the various ABS blink codes mean.



When I jumped the pins, the ABS light stayed on, continuously solid. No blink code. I surmised and later confirmed online this meant my ABS model was likely not functioning correctly. At the very least, the ABS control module was dead or malfunctioning, and possibly more. The modules can be found on eBay but are kind of expensive. I went to a local car junkyard and purchased two for $20 each(in case one was dead). The ABS module is located in the front passenger side of the engine bay. It is secured with four 4mm bolts and has one connector that must be disconnected before removal. It took me less than five minutes to remove it. I haven't found torque specs for the bolts, but since it appears the module is secured to plastic, avoid overtightening but make sure it's snug and secure. This instantly solved my problem. The speedometer began working, the ABS and Brake light turned off, and the check engine light didn't return(after I cleared the code). Surprisingly enough, it also solved my rough idle issue which I had assumed was unrelated.

Hopefully, someone else finds this information useful. I learned all of this through research on this forum and others, as well as my own trial and error. I've attached pictures of the ABS module and where it's located in the engine bay.

 

Interesting post!

Did you have any issues bleeding the brakes?