get an 8' hose made up and a 300 psi gauge from a hydraulic hose supply shop.

 

Interesting update. Still trying to find a pressure gauge, but I talked to a reputable trans shop today. He claims that with the stall converter the Tcc solenoid will do nothing and is normally tuned out because there should be no lockup in a high stall converter. He also said the since it shifts fine once engaged, the pump and pressures are almost 100% fine. I explained all of my symptoms and he said that it sounds electrical. As far as the rattle is concerned, the said even a broken pump wouldn't rattle and it's more likely a converter ratlling. I borrowed a really good scanner so I'll try to see what the computer is doing this evening once some of this ridiculous GA heat dissipates (no AC in the truck). I plan on taking it to the trans shop for diagnostic next week. Opinions?

 

First opinion is don't take it to this guy, as he does not have a clue. A 4L80e with a high stall converter most certainty does use the lock up feature. Some very fast drag cars even use it when making a pass down the track. Clowns like that guy are what gives the auto repair business the bad reputation it has.

 

So are his thoughts on the pump and pressures correct, that the pump won't rattle and pressures are almost certainly good if it drives and shifts fine once it decides to accept a R or D selection?
Is it possible that the lockup clutch in the TC is jacked up causing the rattling and/or the tcc solenoid is bad? I have a new tcc solenoid I can throw in there if necessary. No rattle cold in park, once it placed in gear the rattle starts and continues regardless of P, R, N, D selection.

Also noticed a humming noise while driving (hard to hear over the exhaust) but now that I hear it it seems I can feel it too. Could possibly be the "true trac 4.10 locker" in the rear.

 

put a gauge on it, stop guessing/hoping.

 

Not really guessing and hoping, just going through some of the issues and testing theories while I try to find a gauge...it's not like I can hop over to the parts store and grab one, tried that, it has to be ordered. I'm taking it to a shop Monday for diagnosis...now on 3 transmission shops that say it's electrical and not pressure related, but the one I'm going to is going to do full diagnostic. He said he will check and log line pressures for me.

Changed out the neutral safety switch because it was cheap and the one bolted on was in terrible condition.

Finally pulled codes and had p1810 stored in memory. Did some checking and driving while I had the good scanner and noticed that my minor slip in first problem is that it's not in first, it's in second from a stop. I can command it into first on the scanner and it's absolutely there. If I put the trans in 1 it still takes off in second and downshifts just like D (so my slip isn't really a slip, it's a downshift). Most of the time it will stay in 1 like it should, but one time it shifted through the gears while the selector was in 1... that was odd. Also I never fell lockup...in 4th at a constant 55mph taking it easy it's just stays at 2200rpm, if I let off it doesn't coast it rides the gear down like a manual transmission.

Like I initially said, once it's in gear (2nd apparently then downshift to first) it pulls through all gears flawlessly upshifts and downshifts.

Outside of get line pressure (it's going to happen) does anyone have any other suggestions? P1810 calls for the TFP valve replacement...seems easy enough but taking the pan off can't happen until this weekend.

 

Took the truck to the shop. He ran codes and got 1870, torque converter slippage. All issues still existed on the drive out...I didn't feel lockup and it screamed at 2800 rpm at 65mph most of the way there. Based on that and the whine, torque converter seems like it's done. The shop is going to tear into it to see what damage has been done.