Thanks in advance for all replies. I have a 1997 k1500 4x4. Factory transmission went out and i bought a rebuilt one from a local transmission shop. It lasted for about 30,000 miles then lost overdrive and drive. I have a friend at a body shop and bought a transmission out of a wrecked 97 pickup and installed, transmission lost overdrive and drive after only a couple hundred miles. It's not my daily driver so I let it set for about a year and decided to rebuild it myself. All went well and after install I had no torque converter clutch lockup. Hooked it up to a scanner and cleared previous codes and tcc started working properly. Put about 600 miles on it and noticed no tcc lockup again and it was slipping especially when shifting from gear to gear. Hooked it up to scanner and am getting p1810 which is transmission fluid pressure switch assembly. I bought a new switch and installed but fixed nothing. If I clear the code the transmission shifts fine until it resets the code. I found that once the p1810 code is set and I unplug my mass air flow sensor the transmission shifts fine and runs noticeably better except for no tcc lockup. I took a mass air flow sensor off a friends truck of the same year and it made no difference. After installing rebuilt transmission i noticed my range sensor also called neutral safety switch was wore out and didn't fit on the transmission shifter properly and my indicator lights were always one gear behind on my dash so I bought a new one. After install truck would not start but indicator lights were all correct. Plugged my old one back in and it still would not start. I ended up bypassing the neutral safety switch by splicing into the wire that sends power down to it from the ignition crank position and running it directly to the starter relay. After all these issues I believe my PCM is at fault but want to be sure before purchasing. Any help or advice is greatly appreciated.