[Nashvegas34]

I'm adding this mainly so it shows up in a search for someone else down the road, as it had me stumped for a good couple if days until I realized I was the idiot.

A year or so ago I managed to trigger error code P0751 - Shift Solenoid "A" Performance or Stuck Off - because of how I performed a basic transmission fluid drain and refill. In order to get the container I had on hand under the drain plug, I drove my truck up on some ramps to elevate the front end a little. After draining, I refilled to what appeared to be the right level on the dipstick and went on my way. A day or so later my check engine light came on, caused by P0751. For some reason it didn't occur to me to recheck the fluid level because all of my research turned up people approaching the problem by replacing the solenoid inside the transmission pan. When the light bulb finally came on in my head I checked the fluid on level ground and it was low. I added to the correct mark, then disconnected the negative cable on the battery to reset the ECU, and the error never came back.

There are a bunch of codes related to shift solenoids that may or may not pop up as a result of a low fluid level. I happened to get P0751. Here are others:
P0750 Shift Solenoid "A"
P0751 Shift Solenoid "A" Performance or Stuck Off
P0752 Shift Solenoid "A" Stuck On
P0753 Shift Solenoid "A" Electrical
P0754 Shift Solenoid "A" Intermittent
P0755 Shift Solenoid "B"
P0756 Shift Solenoid "B" Performance or Stuck Off
P0757 Shift Solenoid "B" Stuck On
P0758 Shift Solenoid "B" Electrical
P0759 Shift Solenoid "B" Intermittent
P0760 Shift Solenoid "C"
P0761 Shift Solenoid "C" Performance or Stuck Off
P0762 Shift Solenoid "C" Stuck On
P0763 Shift Solenoid "C" Electrical
P0764 Shift Solenoid "C" Intermittent

[earthrealm]

Great tip

[phattyduck]

The final step is always to check the transmission fluid level when warm on a level surface - the cold marks are only for reference.

-Charlie