P0700

Just after crossing the border today, I put the truck in 3rd instead of drive realized my mistake, dropped into drive while doing about 15mph... Felt like the transmission was slipping and sliding around a little... Then the truck seemed to go into limp mode (that could have been more slipping).

I pulled over.

Checked the code:
* P0700 - MIL Illumination Requested

Cleared it, restarted.

Code came back (or never go cleared).

Waited a minute, cleared the code... waited a minute... Restarted.

All good, not a hint of an issue.

Last time I looked at the transmission fluid it was like new. (about 2 weeks ago)

I'm assuming it was a one time thing and not much to be concerned about, anything I ought to check out?

There was a hell of a rainstorm today so I didn't check all my fluids like I really ought to have, i'll be doing that tomorrow.

G

P0700 is only a request, by the TCM, to illuminate the MIL (SES lamp). It is also an indicator there are transmission related fault codes present, or in history not yet cleared. Most tranny codes are transient, meaning they are one-time incidents and never repeat, or very infrequent. I'm not sure what happened with yours. At 15 MPH, it's hard to say, other than you threw it a curve it wasn't anticipating. Changing the range at low speed shouldn't cause an issue, but alas. Most tranny codes will clear on their own after a few restarts or warm-up cycles, if the condition doesn't repeat.

Yah, that's what I was able to gather googling around.

Any (easy) way to pull the codes from the TCM?

g

We're better than Google, and we won't sell your email and browsing habits.

No "easy" way to read TCM codes. You'll need a capable reader (not cheap), or a Tech II (or compatible) scan tool (also not cheap). If operation has returned to normal with nothing weird going on, I wouldn't worry about it. If you can't repeat it, it was likely just a one-off state of TCM confusion. It could have been a sticky solenoid/valve, program glitch, or something, but if it isn't doing it now, don't lose sleep over it.

While descending winding mountain grades at low speeds with a trailer (25-35mph), or descending mountain logging roads at low speed (10-15mph), I frequently keep the shift selector in 3rd and activate tow/haul. Then, I rarely have to use the truck's brakes.

In all those times, I'll shift into drive and de-select T/H when the grade is behind me and the road flattens. I've never seen any odd trans behavior or any MIL.

Jim