I have scanned it, it comes up solenoid a. But I replaced both solenoids a and b last fall. That's why I'm at a loss, someone told me even of a code like that flashes, it may not be the true problem. Truck comp may just think it is. That's why I'm stumped don't know where to start anymore.

 

Check the ground on the PCM if the ground is loose or a bit dirty it can cause this, had this problem on a diesel swap forgot to hook up the ground and it was in limp mode till we hooked the ground up.(maybe) g/l

 

Did you ever get this resolved? I had a similar problem in my S10, went through all the same troubleshooting and suggestions you have. The local garage told me it was the transmission. I didn't believe him, so I "limped" home and pulled out the wiring diagrams. I eventually traced missing 12V to the transmission back to the ignition cylinder. When the key is turned to the "run" position it closes several electrical contacts, one of which is 12V to the transmission. A heavy set of keys had eventually worn out that 1 contact in the cylinder. Replacing the ignition cylinder fixed my "limp mode" problem, and I only have 2 keys on my keyring now.

 

Well I haven't exactly figured it out. I drove about 500 miles in limp mode and now it has gone away. Back to driving normal. I'm not sure why but it seems to be a 30mph thing. When I would start my truck first shift was fine, hit 30 and no more shifting. I figured it was the tranny, but before it went back to shifting correctly, I coasted, in neutral, down a hill at 35mph. Stopped at the bottom shifted back to drive and it was in limp withou mp engaging the tranny. The key thing has been suggested to me and I do have a heavy set of keys. Thanks for the tip.