So Saturday I drove my 2008 LS460 all over town doing some thrift shopping. Saturday night it rains HARD where I live. I get in my car on Sunday ready to go grab some breakfast and I'm met by two messages on my dash saying "Check VCS system" and "Check Parking Brake system". I use a scanner to get the codes from my car which are; C13AF, U0073, U0100, U0128.

Now, my car had no issues whatsoever on Saturday aside from a TPMS message from a tire in the spare area in the trunk having a screw in it from the previous week. So, I look in my trunk and behind the driver's rear wheel well to see that a fair bit of water has accumulated and there's some water pooling up to the Parking Brake Control Module. I remove the module and let it sit in the sun for a day to dry. Plugged in back in and messages are still there so I grab erase the codes, and grab the new ones. Now I've got; U0073, U0100, U0128.

So my question is, why did code C13AF go away but the other 3 remained? Does it pretty much mean that a new parking module is necessary?

 

I'm not sure why your c13af went away. I'd guess the water evaporated off the parking brake module circuit board. Perhaps it is still functioning a little?
You still have communication error codes for the parking brake module. If it were mine I'd replace it and hope for the best.

I added some rtv around my new module to divert any rain water away from the circuit board.

My parking brake module also blew the 30 amp fuse when it went bad. My code C13af was not intermittent.

 

Alright, I figured I would have to go ahead and replace the module. The 30 amp fuse appears to be fine to me, but I may just buy another before the module just to check.
Did you have to use techstream to reset the module when you got your replacement?

 

Changing the fuse first is a good idea. Sometimes they can appear OK but are not making a connection. I had this happen recently on one of my cars. It uses these tiny mini fuses where you need a magnifying glass.