Shifting issues

[bigfish95971]

Transmission shifting issues after rebuild sent to Dynamic.  Update. SNAFU still. Tried jumper wire. Ran a few days, no change. Put relay back in. Kept going with no first in morning after after 305 stoplights and Overdrive locking it self out in city traffic on warm days. Eventually started going into limp mode(third)regularly sometimes not going into first or OD at all. Replaced NSS and relay, did not help.
Disconnected BD pressure lock cylinder to make sure it was not hanging up throttle cable/valve. I think it was dirty and not returning all the way. After doing so it ran perfect for two days. Then back in full limp mode.

Drove to Sacramento to shop that did rebuild in limp mode at 2400 rpm and 53 mph. Got to Rocklin shop and temp was less than 160 with temp gun.
I had them put in new/rebuilt standard valve body with full electronics. They still had some trouble after installation and said they thought there was still problems with the relay, but when I left it ran and shifted perfect for 2 hours and 120 miles. Shut off for 6 hours and got back in it and SNAFU it was back in limp mode when cold. Drove through town for 30 min and several stops and restarts and it worked again for ride home an hour and half.
Let it sit for about another 10 hours, get in and start out again, back to SOS, in full 3rd limp,mode again. Drove back and forth around home again for 15 minutes and to full warmup and half dozen restarts, and wala starts shifting fine again with 4 and lockup all.
Hooked up a voltmeter before running an got full alt voltage to relay outlet pin the whole time, so I believe relay is fine.
I am betting it will do the same thing tomorrow am, start in limp mode and then start working after warmup and several starts like it was doing a couple of weeks ago, but from the first start, not after some stops.
I am guessing I have a PCM or wiring issue.
Any thoughts or can you tell me how to test the PCM.
Do you have good diagrams for the PCM plugs so I can monitor signals while driving? I do not have a real scan tool.
Can the right used PCM be installed without flashing in VIN?
Can mine be reflashed to repair a corruption?
Any other ideas appreciated.

Edited July 2, 2019 by bigfish95971
spelling correction

[JAG1]

Have you checked out W-T's Grounding Mods? Especially looking at the PCM factory ground to the passenger battery? Might be something there. Also test for excessive AC voltage noise from the alternator capable of confusing the PCM. You may also benefit from doing the complete W-T Grounding modes.

 

I'm very interested in how this comes out.... thank you for sharing and please keep us up to date.