4L80E screwed helping a friend

[Schwind]

I think my 4L80E transmission is screwed. A friend of mine needed to move some stuff and asked to barrow my truck and trailer. I was hesitant to do it but I did. I explained to him how the TCC lock up mod worked more than once. With the emphasis on that it needed to be turned off when he got below 45 MPH. He used it over the weekend and when he returned it, he commented that he thought the passenger’s front brake was going bad or out because it was dragging pretty bad. I didn’t think much about it, it was dark out and about 3*. Went out to day unhooked the trailer and started the truck. I let it warm up and proceeded to drive it. Sure enough it felt like the passenger’s front brake was dragging bad metal to metal drag. I drove it about 10 miles myself this way. He had put about 100 miles on it.

After driving it awhile I looked down and realized the TCC lock up was engaged, turned it off and no more drag. Truck shifted fine for awhile then it started dropping out of 3rd. RPM’s up to 2700 at 55 MPH. Parked the truck at the job site and when I was ready to leave got in the truck and left. Then it began going in to limp mode. It will shift from 1st to 2nd and then to 3rd and then drop back to 2nd . What do ya’ll think the damage is? Are the clutches/bands fried or is the torque converter shot? Once I got home I let the truck sit for awhile and went back out and drove it again. Shifted fine but early. Normally it shifts at 15 MPH then about 25 MPH then around 35 MPH and then somewhere between 45 and 50. First shift was about 12 then 23, 32 and then about 45.

Once I got through at the store, on the way home it fell into limp mode again. It tried to shift into 3rd but fell out again. I shut the truck off and started it again and it shifted but shifted early again.

I check the fluid and it is red and doesn’t smell burnt. It was about a pint low so I filled it to the full hot line. I took it around the block and the shift point seem to be better but it still dropped out of 3rd . It is not throwing and codes, well at least the SES light is not coming on.

What do ya’ll think I should do any advice? I really don’t have the money for a new transmission right now, being so close to Christmas and all. Any suggestion that might get me through the holidays? Has anyone else created their own problem this way that might have a solution?

Sorry for such along post.

 

[docdray]

to know for sure, most good tranny shops will have a computer to monitor the tranny while it is running. without codes possable guesses:
worn or burned friction plates
worn sun gear
piston or spring assembly jammed
reaction plates worn
quad driver module fail
pressure control solenoid-probably not
damaged or leaking seals
bad 2-3 solenoid
just because no ses light does not mean no codes-need checked

 

[dur0maxx]

This is my guess, burnt TCC, that has caused damage to the 3-4 clutch pack. I would say there is a rebuild in your future and your buddy needs to help out with that. Since he couldn't comprehend simple instructions that even my wife would understand, no seriously, I had the TCC mod on my 93 TA and she drove it around no problem switching the TCC on and off right when she was supposed to. JMHO

 

[Schwind]

So can I just jump the A and B pins in the diagnostic port or do I need a code reader to get the codes?

Man I hope I can get this thing to make it through to next year. just don't have the cash to put out right now. Not much business right now in the landscape business with everything frozen and looking dead.

How hard is it to rebuild a transmission? I am no mechanic but I do mostly all my own work on my vehicles. Never have had to get into a transmission before other than changing a clutch or two on manual transmissions.

 

[just a number]

I think 96 and up you needed the scanner so you should be good good to go. There is a link in the 4l80e id/ malfunction thread that'll give you all the codes and causes.

 

[JiFaire]

So can I just jump the A and B pins in the diagnostic port or do I need a code reader to get the codes?

Hey - you can jumper the OBD-I conector to read codes like this. To get the readings from the tranny though, you'll have to use a scanner and have the truck running/moving and up to operating temp.

Sounds like you're off to a tranny shop.

 

[Schwind]

Sounds like you're off to a tranny shop.

Thanks for the how to Jim, I have done it before Just didn't know if i could get the trans codes the same way. Nothing ever seems to happen at the Opportune time. Nothing like lending out the truck that feeds ya. I can say it won't happen again without me in it.

Yeah that’s what I am afraid of. Truck didn't do much better today. It's still dropping out of 3rd. I think the TC is ok but the clutches are shot. Called a couple of junk yards today found some 4l80E's for $750.00. I may have to go that way for the time being. The trans shops here want a minimum of $1500.00 to a max of $3500.00. If it wasn't so frigging cold here right now I might have tried to pull it and rebuild but being the first one I will have ever broken into I don't know how long it would take to do. I saw some rebuild kits and solenoid kits on the bay and can get them for around $350.00. Just don’t know what kinda hours are involved.

 

[JiFaire]

Phone a shop and ask them about a diagnostic. I bet it's reasonable...

 

[Schwind]

I may just do that. The closest one is over 25 miles away though and i would have to drive it there. May do more damage don't know? going to be along 30 mile an hour trip, but probably not to bad slowing down traffic in the snow LOL. Got about 6" today and more on thursday they say.

 

[docdray]

you might find a hole in the wall tranny shop to check it for next to/or nothing if they think they might get some work out of it-the big ones wont do anything w/o charging. Gm dealers are selling the factory rebuilts for 2350 + core, around the metroplex. There were not that many around the country sitting on dealer shelves last I checked. I believe it carries a 3 year, 50k mile warrenty.

 

[625fireman]

I would also look at e-bay for rebuilds. There is one I looked at pretty seriously with mine but I put a NV 45000 in instead. It was Pheonix(sp) trans. Everything I found out about them was good. They build them a little heavy than stock. Decitent warranty too. Again It is easier to spend other peoples money. They wern't cheap. But personally I havent had any luck with GM rebuilds on autos.

 

[Schwind]

Can anyone tell me what the difference is in the transmissions? Will any 4L80E work?

With the 94 6.5L S engine. I have found a couple of trans at a few junk yards but they want the code off the side to match up. One of the yards said that mine being a 94 had to be year specific and code specific.

The trans codes they gave me are:

HCP
KSP
LBP
LYP

I just need a little clarification why not just any 4L80E out of a diesel will work. Is it the electronic match up or gear ratio’s?

Any help would be appreciated.

 

[Sunshine]

Maybe going a bit off track here, but i had to ask

JiFaire(Jim) you say Never put a jumper with key on,,, what's the consequences,as i`ve read you would have too ,to delete the codes.. back & forth for 2 seconds from the ground pin?

 

[Schwind]

Got under the truck today slopping around in the snow and got my code off the trans. my truck is code LYP. Called the yard and they said that the 94 LYP is not interchangeable with any of the other codes for the 94’s. Also on a state search there isn’t one to be had. Guess I am in for a 1800.00 rebuild instead of a 750.00 swap.

Does anyone have conformation of this or can dispel what I have been told?

Any help would be appreciated.

 

[hereismylife]

I am wondering why you don't try and change the fluid? While you are doing that add a 2 bottles of lucas trans helper and see if your problem goes away for now until you can get money for a trans.

Old fluids can make the trans do odd things.

 

[Schwind]

I am going to change the trans fluid and filter and see how much gunk is in the pan. just have to deal with the holidays first. I was thinking of using the lube guard for the additive.

 

[Schwind]

I was able to get the DTC's off the truck today. The SES light didn't light up but I got these codes from the port.

16 - Vehicle speed buffer fault

72 - Vehicle speed sensor circuit loss / output speed sensor

83 - torque converter clutch

So from what knowledge I have of the codes. Code 16 is do to code 72 which inturn is do to code 83. In other words being the torque converter is slipping 83, the output speed sensor is not receiving the proper signal 72. Which in turn the VSSB is not getting the correct voltage pulse information for the PCM.

Can anyone confirm this for me? Is it possable that all that is needed is a new torque converter? Or is it possable that the bands are slipping giving me the code 72.

Any help would be greatly appreciated.

 

[docdray]

well, 83 is the tcc or QDM. first verify solenoids in tranny are ok by checking resistance, especially the tcc and vss(at least it doesn't cost anything). then verify voltage to tranny on wiring harness(battery voltage, pin e, red wire). if solenods ok, and voltage bad, check QDM-as well as the QDM could be damaged not grounding solenoids during operation...if everything so far checks ok, code 72 indicates slippage in side tranny-something worn, damaged or leaking. of course a scanner check would help a lot.

 

[tracy]

Code 83 is tripped by using the TCC switch, some trucks seem to throw the code and some don't, for example If I recall correctly Jfaire says his truck doesn't throw code 83 but mine does. I have experienced no ill effects from code 83. With codes 16 and 32 I would buy 1 new VSS (there are 2 in the trans there cheap around 20 to 30$) and check wiring and connectors to the VSS at the same time your changing the old one out. If that doesn't help then swap the new VSS into the other original VSS and put your old good VSS back in the same position you took it out of, there both the same and takes less than 2 mins to change. I really don't like throwing parts at something hoping it will work but in your case the codes tend to point towards one of the two VSS is bad, and thier fairly inexpensive.

 

[Schwind]

A follow up

Sorry it has taken so long to get back to this post.

I did as suggested and changed the fluid and filter in the transmission. I was suspecting to find quite a bit of band debris in the pan. But to my surprise there was very little. Mostly just around the pan magnet and very little there as well. I cleaned everything up and then sprayed the clean pan with carburetor cleaner to eliminate the lint from the rags.

I was unable to get the old o-ring flange out of the hole in the transmission. So I reused the one that was in there. If anyone has a suggestion in getting the old one out next time I would definitely appreciate it. The new filter snapped in without a problem. I cleaned up the surface of the transmission and the pan for the gasket and reinstalled the pan torqued the bolts to 18 ft lbs. As instructed.

I put a pint or the 10 oz bottle of lube guard in and then 13 pints of trans fluid. I was told that it would take 15 pints to fill the trans back up but it was full with just the 14.

Anyway the transmission quit slipping back to second. It seems to do better the longer it has been run. It has been about three weeks now and the only thing that I can still see that might be a problem is that it is a little slow shifting from 2nd to 3rd sometimes (possibly slipping a little). It seems to only do it without a load as well. I am thinking of putting a few thousand miles on it and changing the fluid and filter again. Any suggestions on how long I should wait would be great.

So far so good for the last few weeks hope it hangs in there for awhile. At least till I can get the money saved up for a rebuild.

Thanks for all the help and suggestions. If it wasn’t for ya’ll I probably would have been paying for a rebuild already and not known how bad I was being taken. THANKS AGAIN.