2003 Suburban tranny/electrical issues

Hi,

I have a 2003 Chevy Suburban LT K1500, 5.3 L engine, 4L60E transmission, 127,000km.
Last week, after a five hour trip pulling our travel trailer, we parked the truck in the garage overnight, the next day on start-up I lost 1st and 4th gear, it worked fine the day before. The only thing I can think of that happened on our trip was hitting a large pothole about 3 hours into the trip(loose connector, but I think the problem should have occured right away)
After some research, here is what I done/found.
I dropped the pan to check the shift A & B solinoids and the oil. The solinoids checked out O.K. With an ohmmeter and applied 12V to them and the function. The oil was a little darker than new but due to the mileage I feel comfortable with that. I also checked the voltage to the solinoids(cct#1020)with my key in the 'ON' position and O.K.
I got hold of a code reader and these are the codes that were set: DTC PO740, DTS PO785, DTC PO 1860, DTCPO 740, DTC PO 753, DTC PO 785, and DTC PO1860. All of which have the 12V supply to the transmission in common. I checked the IGN0 fuse in the fuse panel and O.K, I also checked in the fuse block under the hood(not sure if that is just a junction point or what, lots of pink wires in there).
Gm suggests useing a inline 20-way connector at the transmission for troubleshooting, but I don't have access to one. The other thing in common with these trouble codes is the PCM module.
Here are my questions:
Where is the PCM module(in case it is a loose connector to it)?
Would there be other problems if the PCM module was no good?
Am I missing something?
Thanks in advance.