I'm going to call this a wrap. It was the actuator itself. After removing the unit, the gear spun freely so I was concerned it wouldn't be a fix. Drove around town and no lights. Upon reinspecting the old unit it does have a very slight gritty feel while it spins, which would explain why it only threw codes at highway speeds. I was able to get the car around town by keeping it under 60. To summarize this issue, always check 12v first. If it happens only while raining, it is an electrical connection; blue wire from the park lock circuit in the fusebox, green wire from the tcm to the unit, master white relay in the fusebox or the fuse circuit connection itself. If it happens at high speed it is mechanical, hence the unit itself. I replaced the tcm but I'm guessing that is the least likely to fail.
??? The park actuator doesn't do anything that's connected to how fast you're driving the car. It spins for a fraction of a second when you shift out of Park, and stops. It spins the other way for a fraction of a second when you shift into Park, and stops. That's all it ever does.
It doesn't matter to me why it is speed related. The codes would only trigger at speeds around 60+, as others have reported. The important thing is getting it fixed. Once again. Wet weather issue = electrical. High speed issue = mechanical. Just my experience and thanks for your input and feedback.
