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97 4L80E dropping out of TC lock up

for clatter to go away after a restart I have no idea. but just guessing some kind of electrical issue. or ECM going south? maybe temp related within the engine compartment. how does it act when everything is cold? not trying to point at the ECM but if it's in the engine compartment and heating up were the circuits within are breaking down. it's rare but not impossible.
 
i think it was some sort of knocking, came mostly from bank 2.

i think i need to go though my ground points. make sure they are good.

i also need to get some needles and alligator clips to back probe the PCM.

ive been musing about the health of the PCM too.

but then, its up above the radiator, so its in cool air all the time. only while idling, it gets a backflow of hot air that circulate the engine bay
 
after todays issue with the MAF i probably order a new one too. i tried 2 from O'Reilly, both over reported by 15-20%, not acdelco though. i probably order one through rockauto. and i add that harness and a filter, and while i change that i check for that broken spring. going to be next week. ill report back.

any hints for a shop before or after the Seattle/Vancouver border?
 
Be careful what you order from RA! there are lots of counterfeit chineesium knock-off delco parts. always replace with GM or AC Delco, but get them from authorized retailers. you can look them up on the AC Delco website. and never trust the jungle site ether. some parts made in china are "OK" to use, but when it comes to things like sensors or major components that could leave you stranded or worse, destroy your engine/trans always go with reputable quality parts.

ask me how I know LOL I learned the hard way as did others here!
 
If your transmission is reaching operating temperature and drops out of overdrive it could be that your Torque converter clutch (hydraulic system) from the TCC solenoid valve (leaking) all the way through the actuator feed limit valve (side loading) ect.. When the fluid gets thinner you will see this. But remember this is a very common possibility and the achilles heel of the 4l80-E.
There are a few things that you can do electrically to ensure a good shifting transmission.
Remove, clean and reinstall the battery negative lead. Battery to body electrical lead, the engine to body ground lead, PCM ground lead if you can find it. What happens is that corrosion can build up at these leads causing resistance and this interferes with the electrical circuits for the transmission.
You can troubleshoot the TCC solenoid using a multimeter set on resistance. I can't remember what the resistance is on the TCC solenoid but you can find it on the internet. It would be ideal if you could check it while the transmission is at operating temp. If the resistance is excessive then replacing the TCC solenoid can fix your problem. Even so this is a slim chance. The passthrough connector that you had removed has the pins to check the TCC solenoid so you wouldn't have to drop the pan to check for resistance. Passthrough.pngSolenoid Resistance.pngSolenoid Resistance.pngComponent resistance homework.JPG
 
For the hydraulic side of things. The transmission is told what to do by the TCM and in your case this begins with the torque converter solenoid receiving an electrical signal of pulse width modulation. Think of it as a way to increase the length of throw to the TCC valve.
When the transmission is not staying in OD when its commanded to.
A couple of common problems. Frequently the valve, valve seal and or bore could be worn. This is very common because of transmission fluid particles wearing away those components. The AFL valve (Actuator Feed Limit) could be worn as well.
When these components are worn and as the transmission gets to operating temperature the fluid thins causing the transmission to not follow up and remain in torque converter lockup.
Find a reputable transmission rebuild shop to have the transmission torn down and gone over. They can repair and replace the TCC solenoid, the valve and repair the actuator feed limit valve. Better yet to rebuild the transmission.

I will tell you that this electrical and hydraulic issues are not exhaustive but an idea of what you might be up against.
 
adding a bottle of lucas trans fix will thicken up the fluid some and can tell you if things are worn inside. if the trans shifts better and stays in 4th for longer with the lucas added, that is a good give away that its time for a full rebuild.
 
while its almost 30 years old now, my trans is just past 60k miles young, mostly driving by on old guy treating his new RV with soft paws...

from what i see, i dont feel that this trans is dead.

i do also own a burned Ford AOD, burned by the rip off a tourist trap in Atlantic City that was tasked with fixing the TV cable to TB linkage and my stupidity of not feeling it slip on my very first drive in the 88 Town Car. so I'm burned, pun intended. and this one feels totally different than a burned OD or gear clutch.

my money is on that broken spring, cause that does perfectly explain its behavior....

I'll check, but don't hold your horses, don't know how much time I have on my hands while in Canada.

edit, and i also own a 722.4 in a W201 Merc, thats coming up to 40 years now. with way way past 1 million miles, and I own that particular one since its 100,000 old and i haven't even changed transmission oil since i owne it or checked on the transmission fluid level in the past 250k miles, and its a towing rig.... its just working. that rig inst worth the new oil, but as long as i can weekly haul my car carrier through half Europe with it, ill do it. until the day she dies. but that probably will come in the form of another (3rd now) differential replacement. and besides that i own a 722.112 in a W123 and a 722 in a W111, all working since decades with out even touching them.
 
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mannebk said:
while its almost 30 years old now, my trans is just past 60k miles young, mostly driving by on old guy treating his new RV with soft paws...

from what i see, i dont feel that this trans is dead.
Click to expand...
Your transmission is telling you that the handwriting is on the wall. If you are lucky you can repair the electro-hydraulic portion and come out ahead. If you drop the oil pan and see a lot of "sparkly".. this will add onto your OD problems and issue.
What you are going through with your 4L80-E is what untold thousands of others have already experienced. A lifecycle if you will. A 4L80-E goes through its 4th gear OD throes very different than a 700R4 or a Dodge 48RE. That 4L80-E of yours was one of the strongest light duty transmissions put into production at the time with no bands to adjust like a turbo 350. That dependability came with its own cost later down the road. The overdrive 4th gear will start to fail. The tiny particles within the fluid caused the wear. The lack of cooling the transmission because of its being in OD sure didn't help matters. The 4L80-E and its concept is well over thirty years now and cycling out. If you want to keep it then my recommendation is that you get it completely rebuilt by a reputable transmission shop.
 
if you comment on a thread, pls, first read it. thats all stuff discussed 2 pages earlier.

ive done transmission rebuilds, i own a very special shop, where folks come to when other shops can't fix it by plentiful throwing parts at it... but im 5000 miles away from my tools and have a transmission that does not behave like a failed band.

I dropped that pan, and out came 55k old fluids but no metal or clutch material, pics are in here, i pulled the harness plug, its dry. pics dito

that tells me, i have a good transmission, not a bad one.

that also tells me, i need to find the real reason, cause a rebuild is probably not going to fix it.

i know, with US automatic transmissions, because they are what they are, first step in fixing a funny behavior is, rebuild it for upwards of 4k.... might. ot fix it, but introducing a lot more reasons for more funny behavior...

all the good transmission people ive been talking too have been trying to sell me a full rebuild. and non was willing to explain to me why that would fix my issue. cause if you don't know whats wrong, do a full rebuild.

its like the traveling mechanic that tried fixing the funky idle (caused by stuck valves) for my previous owner by selling him new batteries, then a fresh fill of fuel, then a fuel pump (both times he siphoned the "old" fuel into his rig, no its not hear say, i saw that on cctv footage PO showed me after we became friends), then new distributor, wires and plugs, then new injectors (while at it, dropping a self tapping screw in the only cylinder that had no bend pushrods.) after that my PO had it towed to a good shop. who actually found whats wrong and quoted him way over 20 grand for 2 new heads and a redo of all the stuff the other guy did. so he put up this unused basically brand new 27 years old MH for sale, to give away for almost f-ing free. i came in, swooped it up, pulled the heads, polished the valve stems and brushed out the guides, grinded the one with the screw in it, put a set of new lifters and pushrods and a gasket on, now i own a 25k MH at costs below 2k. (that i ignored the cheap parts of the traveling guy came to haunt me. 1000 bucks for a tow for a worn down distributor gear that made the distributor spin freely, and a set of new injectors, cause when hot one of em was getting stuck wide open and an other one was stuck shut, funny hu?, that all in was another 2k. but back to topic)

let me tell you, a worn out band slips, it does not shift hard and then go soft. that's a sign of missing oil pressure at the servo after the shift is completed, and that's nothing that comes of a worn band or a stuck valve, broken cable, dead coil.

ther are many possibilities here, but a worn band is absolutely out of question.

in the end it comes down to anything that could starve the servo off oil pressure in 4th only. like a PCM that goes bonkers, a valve thats supposed to be in one place while it wanders due to broken spring, blown out seals that only affect the 4th gear.

i never worked with a 4L80E, hence why im here, to pick your knowledge and brains, selling me a full rebuild is not what I'm here fore. thats beend done to me already, no need to have it a second time.

and the 1-2 valve spring is one of these possibilities and easy enough to verify its good.

what i would like to do as a test is hook a manual shift box to it. and go hard 4th, see if it does the same funny things. But then, pulling TPS seams to make my PCM go into some sort of fault mode where it locks TC up and just shifts hard by rpm/speed

in the meantime im happy driving in 3rd gear. its where that engine transmission differential and tire combo wants to sit mostly anyway with pushing a 10 ton class a MH down the interstate.

oh, and we also ascertained that i have a PCM, not a TCCM or a TCM or ECM

and since it does actually store faults, its likely this PCM is a good one.

I'm certainly not going to push my multimeter probes into any plugs, thereby ruining the pins in there.... but i go get some alligator clips and im going to get me some needles to very carefully back probe my PCM plugs and put some measuring devices on them.
 
and a friendly sould came forward with a test schematic.

so my next thing is get a external pig tail and make sure my problem is inside the trans vs outside the trans...

then we can do qualified assumptions on what's actually wrong... we basically will make qualified asses out of u and mptions. ROFL
 
GenBiltstein said:
As you well know you can drive in third gear back to your shop and take care of matters there.
Click to expand...
i know that Americans are notoriously bad in geography...

the US isn't big enough to drive 5000 miles in a straight line.

from Seattle to Miami is 5500 kilometers, not miles.

and my MH fore sure doesn't float.

so no, i cant drive it in 3rd home and do it im my shop

besides, even if i ship it on a ro-ro the first officer who put a tape measure on my MH would put me right into jail. no way of driving a more than 2,55m wide ting in Europe without special permission, and that's only granted for loads, or farm equipment. both is not what a MH is.
 
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