now what good is checking your engine when the transmission is the problem? there is no check transmission light persay but if the problem gets bad enough to effect overheat things the od light will come on...
and yes you get transmission codes as well as pending engine codes without a "check engine" light...

the TCC clutches almost never fail btw... gov soleniods do all the time....I recently just had my tc fail and needed a rebuild when they go they leave aluminum shavings as well as steel ones in the valve body passages which make it rebuild time...... I noticed right before the converter totally failed you will get unusual rpm readings in od like its stuck between drive and od.... and band adjustments wont help at this point... go ahead and ask a transmission shop... its they are at the point where they are slipping they are shot... sorry...I feel your ..or rather felt, your pain..

 

or if you have a pc or andriod phone get an "ELM327" on ebay for 15 to 20 bucks.... I never use my scanner anymore this thing does so much more...and works with all sorts of software like "torque" on the market... even gives you things like hp and quarter mile times...

 

I am unsure how long you have owned this truck, but beware car dealerships. The check engine light is supposed to come on for a second or two on anything made in the last 20 years when you first crank it up, then it goes out if there is nothing wrong registering. If you test drive a vehicle & the check engine light NEVER comes on, even for a second at start up, that means someone removed the bulb for it to disguise a larger problem. Several dealerships in my town were sued out of businesses for such practices. Beware

 

I'll say it again, I know from experience the check engine is for engine issues and doesnt come on for transmission problems...I know this from experience and multiple transmission problems and codes that do not cause the light to come on... and then I read and found its not supposed to for transmission problems...

 

Well, im back where I started. The governor solenoid and pressure sensor, TCC solenoid and harness were replaced. The harness and attached sensors were replaced without removing the VB. I had a heck of a time understanding that the o-rings were holding the accumulator and connector so tightly. I had to use some leverage to overcome it but it did drop down. I held the spring in place with a putty knife so it stayed in the hole. Buttoned everything back up and took her for a test drive.

I drove it for about 15 minutes yesterday and she drove perfectly on upshifts and down shifts. After a 3 mile run I came to a stop sign and felt a big clunk which I assume was the TC engaging. From there on I had the original issues which started this thread along with the ocasional whirring noise like the TC was running low on fluid. I get the same noise after warm up moviing the gear shifter from park to neutral. If I reved the RPM's up in park then move it to neutral the noise will sometimes go away.

Now, this morning with the fluid cold I took her for a test drive and never felt it leave second gear even after warm-up. I am planning to replace the external Transmission Speed sensor and if that dont work I will replace the inline check valve or just do the "check valve delete" procedure.

And if either of those dont fix it I'll open the tranny again and adjust the bands, fluid line pressure and throttle plate adjusments. Take it for a test drive again and if that dont fix it I think I will replace the Torque Converter and flush the lines. I wish I had cleared the P0740 code after the parts replacement but before I had taken it for a drive this morning. I deleted it after my test drive and dont want to risk any more damage on another test drive.

Also when I last dropped the pan I noticed a crack in the valve body which appears to only be alonside the screw. I am hoping that this crack doesnt extend into the VB any further than the edge where the arrow points to.

 

Recheck fluid level. Might still be a bit low. Gotta check it in neutral. Park will give inaccurate reading.

 

I'll do that. I have put 6 quarts in it so far but I think it leaked bone dry sitting two days without the pan. I added the picture after you posted that so if you change your mind i'll understand.

 

Maybe the VB has been over-torqued at some point? That would certainly add to your shifting woes...... If you go in there again, it probably wouldn't hurt to just break 'em all loose, and then re-torque the bolts.

 

from everything you describe it sounds like your torque converter is failing... the clunk at the stop sign could not be from worn slipping bands... when the converter starts to go it leaves shavings which get recirculated usually plugging the governor pressure solenoid screen first but also intermittently plugging other passages causing issues... when it fails fully it will stall the engine right out at stop signs...
Adjusting the bands on these transmissions never seems to anything... If they are that far gone that its slipping they need to be replaced... the clutch material on the bands looks almost like a piece of sandpaper...its very thin.
what color was your fliud bright red or a brown burgandy color? if its the latter its burned up.
BTW you can tell what gear your in by just watching the rpms unless you dont have a tach? I just went through all this and had the limp home issue where it wouldnt go past second gear... replaced the soleniods and such only to find it was the converter and it needed a rebuilt...

 

It still sounds like the piston seals on the front clutch are shot, which will cause it to drop out of 3rd gear and back to second. The whirring noise is probably just the pump gears. The clunk you hear at a stop is the rear band engageing and dropping the trans into first gear. What actually makes the clunk is the engagement between the front clutch drum and the sun shell case which houses the rear clutch that is engaged in 1st and 2nd gear. The clunk comes in when the front band goes loose for 1st gear.

As long as the only crack in the valvebody is where you see it in the picture,you should be ok. The problems arise when it cracks between pasages or on either front or rear of the body where the passages to the trans body are located. I would suggest removing the valvebody and doing an air test on the body to identify where the leaks are. The clutch ports will create a light thump( clutch piston engageing ) and there should be no air leaks heard. The passages for the servos should activate the servos with no air leaks heard. The servos apply band pressure.

Here's the best way I can explain which passages operate what. With the valvebody removed. Looking up at the trans body. The first passage to test will be located between the servos on the passenger side towards the rear of the trans.This will operate the rear servo.

The next one will be towards the front servo in the same recess where the rear passage is located. Both ports favor the outside of the trans body and there are bolt holes located just to the outside of each port. This will operate the front servo.

The front clutch apply is located at the front of the trans. Passeger side to driver side there will be a bolt hole, to rectangular holes(the first one is pump suction, the second pump pressure) then a bolt hole. The first passage after that is the front clutch apply. The next port is the rear clutch apply. The next to ports are for the converter, then a bolt hole. the very last port is for the cooler.

At the rear of the trans,are two more ports,one is for the OD clutch apply and one is the cooler line.

Hope this helps. This will tell you if there are fluid leaks that are causing weak or no clutch apply.