Tell me if you heard this one before (And yes I have searched this till I'm blue in the face)? So I bought an old 98' Burb from a not too reputable couple. It had been in an accident but the guy had thrown a new A-arm on it. Trans was toast he said and sure enough he was spot on. I barely made it home in 1st gear after 2nd went on the freeway. I would up rebuilding trans (old one had a reverse piston crunching 1000 pieces through everything. Didn't want to use it but, didn't have a vehicle and couldn't get my hands on a decent core. I had done 3 4L60e's beforehand never had a problem. Anyway, I put all new frictions and seals, a few bushings, New reverse piston and fired it up. Not too good! Trans was in limp mode or something cause it wouldn't shift to 3rd. So I put a pressure gauge on it and it was maxed out 220psi in what gears I had all the time except when when I would put it in reverse it would drop down to 75psi for a brief second and then jump right back up. I was getting codes like P0758 EPC solenoid 'a' Electrical & P0711 Trans Fluid Temperature Circuit A Range / Performance. Those along with a misfire code. Oxygen sensor Bank 2 codes & a stop switch code (note sure actual code this one). So I checked the harness connector to trans and it looked like this

(Show pic). When I saw that I just decided to replace the harness.

Let me preface what I'm about to say next with even more confusing details of my FrankenBurb project. I had noticed that somebody must have rebuilt this trans before because I noticed that the valve body was an 02' Reman with Annular lockup. I ran with it thinking that whoever had put it in must have had a reason and my research suggested it was not totally out of the question?? I also assumed that whoever had put the Reman had switched wiring harness. Although now in hindsight he must not have because it still had the early style EPC?

So given my low budget and figuring that the internal Harness was cooked I switched it out for the newer style on from a 2001 a long with newer EPC.

Interestingly, this fixed my "limp mode" high pressure but, now I'm only showing 50psi at idle in all gears and I still don't have 3rd.

It was either the new harness or the 1-2 accumulator and housing I changed (also to the newer style).

Anywhoo, if somebody could throw my a rope… I might not drown on this project.

Oh and I did buy one of those foxwell scan tools with trans diagnostic capabilities and there were some questionable reference #'s I'm not sure I'm reading right.

Last thing I can think of is the harness that had the staining inside the plug (See below)… the one that was in it. When I checked the scan tool on it I'm fairly certain that the EPC had 0 Volts to it. My thinking was then maybe it wasn't limp mode then if I was reading it right. The new harness seems to have voltage to EPC at .20 constant but, it has low pressure in the trans.

P.S. when I blip the throttle in any gear I do have now it goes from 50 to 100-120psi easy???T

Thanks to any ghouls…. Guys out there for a treat as this is a real trick sitch for me.

Bob

 

Not sure where to start so at the end seems good. You solved what appears to have been limp mode.
You now have presure variance with a 50 psi at idle number little low but not terrible, you tip in it jumps to 125 also good. probably much higher at WOT based in previous limp mode reading base on 90 percent in tune should jump to about 200 ish.
But what I am not clear on is what is it not doing now? Does it change gears? how do they feel if it does ?

 

Thanks Frank .. been reading your posts for some time on here. I posted because I never had a problem that I couldn't figure out where I screwed up before but, those were stock never rebuilt trans and this one has been smothered, covered, chopped and diced.

My scan tool which I'm a newbie at using is showing it going from 2nd to 4th sometimes and sometimes it feels like it's just slipping the 3-4. I probably burnt the new 3-4 clutches even though I have only driven it 5 miles total and it's barely been in 3rd or 4th but, when I did change the harness fluid did seem to be semi black but not smell bad. I was just hoping to get some ideas of if /what I could try without rebuilding it again and having this problem burn up another attempt.

I noticed on my scan tool the there is a -6.6 reference for 2-3 shift error with a value of -1.63. What is that?

Also I forgot to mention I have a Transgo 96-03 Separator Plate (not drilled) and a LB-1 boost valve installed along with a Corvette Servo and GM's longest servo pin. I had some serious (7/16ths) play on my servo cover and when I installed the torque converter there was a much larger than normal space (3/8") between flex and TQ that I shimmed.

I seem to be getting a bunch of new but, different fault codes with new internal Harness but, not the original ones.

Bob

 

Sounds like you still have electrical issues, All electrical codes should be resolved first in all cases before anything else is done. Check grounds, power , plugs everything. I even had a customer call for a trans yesterday and I always ask what was wrong with old one, Sure enough he gave me several codes . I told him while I will be happy to sell him a trans he should first deal with the codes as they are all electrical open/short codes.
While it would not be my fault, Nothing more depressing for a customer than to get a new trans and still have same issues .

 

Yeah I am just now going through all the new codes it threw me after I reset the PCM (unhooked battery for the night) & changing the internal harness to the newer epc style one. I was leaning towards it being electrical too but, I checked for power at Pin E and while it is off by .15 V with the old harness compared to battery voltage, I was getting nothing to the epc hence the max pressure. When I changed to this alternate internal harness I am getting .2V to the epc but still have low line pressure. I know it could be a myriad of things in combination on this one. Just trying to narrow it down. I will make some more tests over the weekend and post results.

I was thinking that it might be the PCM from the accident but I have know idea how to check anything with that. That's why I kept wondering about the weird reference voltage my scanner was showing me.

One question I was wondering too is, I tested the input drum to shaft (not hot) before installation but, it did not seem to engage the 3-4 clutch pack as firmly as I remember on the other 3 I did. I checked the input drum for the small check ball in the drum and it was there. I then checked all the other 1/8"? check ***** I could think of and everyone was there but, perhaps I missed one. Reason being was when I opened the trans originally there was a tiny check ball the size of the one in the input drum fell out of the case side after removing valve body. It is not a normal size 1/4" check ball. It is not one from the molded piston. If it is not one of those I'm not sure where this came from. If it's not one of those and another one I missed could it cause a pressure loss of 3rd gear circuit?

Bob

 

This probably isnt your problem (but it could be), but my advice to you is, when you build a 4l60e make damn sure you press the input shaft out of the drum (aluminum drum) and press it back in with loctite sleeve retainer. Thats a huge leak potential area that causes 3-4 clutches to smoke. skip this step and you are playing russian roullette with your 3-4 clutches.

 

Thanks Kfxguy.. I'm going to be trying some more tests if this rain ever lets up...I live in Seattle area. I was wondering if when hot the input shaft to drum could be part of the problem. I did air test it at room temp but didn't try the dishwasher method. I also blew air through the shaft but, my POs pancake compressor is weak and I wonder if there was some large chunk of aluminum from the destroyed reverse piston that got lodged in there.

I will eventually have to tear it down but, I'm holding out a sliver of hope that it's only an electrical issue and my clutch pack isn't totally smoked. I just don't know some things I can try without a bi-dirdctional scan tool

 

If you have pinless accumulators it could be from the 1-2 accumulator and or the forward clutch could also be from one in the pump and of course the input drum. fwd piston. Reverse input and several other places I may be missing, If that tiny ball was in there is goes someplace and is necessary .

 

+1000 on this!
I recall a thread where the OP was a pro build who tested all the input drums from 4L60E that came in for a rebuild and determined that 50% of them had a leak in that area. IIRC he was testing them after heating in boiling water.

@Kfxguy - are you suggesting just loctite, the Sonnax reinforcement ring or something else? The Sonnax ring has been my choice, but they you have to use their supplied Overrun piston which is a bit more difficult to install. I've heard that plenty of building find just the remove and re-install with loctite to be sufficient.

EDIT: @Kfxguy explained to me that while the original Sonnax reinforcement ring required a special aluminum piston creating difficult assembly, the current (newer) version is improved and easier to install.

 

if it’s just a stock rebuild, I just use the loctite. If it’s a hi po build or a young kid driving it, I install the sonnax reinforcement ring. I don’t find it any more difficult to install? Maybe more difficult to get the snap ring back off on disassembly, but I feel like the piston goes in easier because the inner seal is an oring instead of a lip seal, which I make a seal protector for that anyways.

I’ll never forget. I had a trans come to me that another builder in town kept fixing. It kept burning up. I think he tried three times. Then they brought it to me, I wanted to start from the beginning so I did my own complete rebuild. When I pressed the shaft out, I touched the shaft with my press anvil, then started to pump on it, and I didn’t get a full pump and the shaft fell out of it. Yep. There’s the problem. So far it’s lasted longer than the three times he was in it. I wonder why. Plus not to mention, beforehand it would never shift when commanded. It would constantly hit the limiter unless you commanded a far earlier shift.


I feel like the shaft thing is a major thing overlooked and I’m guilty of it. I’ve had a few failures through the years and no apparent cause, but I wasn’t checking this shaft. I always assumed it was good unless it was disconnected from the drum or the drum was cracked. I’d be willing to bet that most builders don’t even check it. Much less press every one out and loctite it.

honestly, whomever is reading this thread, how many of you press every one out and loctite it back in. Not check it, just loctite it anyways? I don’t bother checking them, I just do it. Every time. It’s more work. But so is pulling the unit back out and tearing it back down, cleaning and fixing. Plus the embarrassment of failure. That’s one thing that I cannot chance. If something goes wrong, I don’t want it to be because of my laziness or negligence.

 

yea, aluminum expands more than the steal shaft, so it’s possible it could not leak at room temp and leak at 150+ degrees. Honestly, I’ve heated stuff up that was a press fit to 150 degrees and it slipped right in place with the receiving end being heated up.

 

Well the rain let up a little today but, I didn't figure much out. It's still doing exactly the same thing it was doing after I put the different internal harness in. What has me stumped is my scan tool is showing that the solenoids are turning off/on as they should but when I go from 2nd to 3rd it just revs the rpms even in manual unless I mash the gas hard then it bucks a couple times and seems to jump 3rd and go to fourth. When in 4th the rpms are really up there between 3500-4500 @35-40mph. I'm not 💯% sure but it appeared to me that my scan tool (again which I am new to using) shows something called the OSS (is this the speed sensor?). It's is about a 1000 rpms different than what my gauge reads when I the higher gears. Will double check that tomorrow.

Also, when I built this one I noticed that one of the Accumulator pin bores had suffered some damage from the reverse piston chunks going through it I'm assuming. I posted a picture of it here.

Does anybody think that the damage to the pin bore could be causing this "bucking" when going to 3rd.

I thought about the SONNAX pinless accumulator setup but, I had already ordered the aluminum ones and have gone over budget pretty bad already.

Feels like something to do with the Torque converter. 1st and 2nd shift great but, the rpms skyrocket when getting into 3-4. Actually it doesn't even really hold 3rd when punching it. It goes almost straight to 4th after it kicks.

Thanks for everyone's suggestions and help.
I will do some more stuff after I get off work Wed.

 

No the 4th acum pin bore would not cause your issue . But if you are skipping over second and hitting 3rd that would indicate some issues with the band or 2-4 servo assembly

 

Well guys I will not lie to ya I f'd up. And, while I'm not sure if this is the root cause of my problem, it definitely is a hard lesson learned if it is. In my haste to get this back together and having had other problems the night I put the 2-4 servo in. Which I did under the truck instead of on the bench. I hindsightedly grabbed the wrong spring from a parts lot I had and threw it in the servo bore. In my defense I was more worried about using GM's longest servo pin and was also wondering why my servo cover had so much play. Also, why my cheap Recon TC too had so much play when bolting it up. Also done that same night. Live and learn I guess. Anyway, although nothing has changed with the driving conditions except a little less bucking when flooring it to get it into 3rd gear. It is still doing exactly the same thing.

​​​​​​At this point, given my blunder, I will understand if anyone doesn't want to speculate on what this could be.

You probably nailed it Frank 😂.

Bob

 

What is your servo end play now?
Not to ask insulting questions, but have you double checked the trans fluid level? The correct dip stick is installed? And you know to check it when hot with engine running? (Although I find it reads almost an inch high when cold and engine off.)
We like a good challenge.
And look forward to hearing the solution.

 

The wrong spring unless it bound up but looking at photo I do not think it would, In fact I prefer a stronger spring and when I can get them use the 400 int band servo spring instead of the stock one as its a good bit stiffer.
I still think your issue is the band is delaminated - off the peg or the pin went beside it rather than hitting it.. I would probably pull unit myself but if it's the band peg in the case that can be determined pulling the pan and possibly corrected with VB off.

 

mrvedit I had almost 5/16-3/8 servo cover play until I added the GM longest pin. Now I have about 1/8".

I did buy the new 2-4 band (stock Borg Warner HE) from an online eBay store and when it arrived it was not symmetrical. It seemed to be out of round (if that makes sense. There were no crease or folds so I figured the heat would mold it to the shape of the drum. One other side note I did use the reverse drum of my parts shelf from a V6 but it looked identical.

Frank I think you make a great point as the pin and band "hole" were off a few mm and the band seemed to have a lot more play then usual. My second gear works great though? It's only 3rd that it is not engaging well. Are you saying that the band is cocked / angled from mis-alignment and is not releasing during the 2-3 upshift correctly?
I plan on dropping the pan again Thurs or Fri. weather permitting. and see if I see anything like that.

Will keep ya'll posted.

Bob

 

Do me a favor cause I am feeling a little dumb. Please recite in a single post again exactly what is happening ,
Thanks
Frank

 

I'll try to summarize a little better Frank but, it's still a lot I know.

I bought this 98' 5.7 Suburban. Guy said the transmission was shot. He was right, Reverse Piston was in tiny pieces. Rebuilt anyway using spare parts of the shelf (sprags, rear planet w/oil slinger, pump, hyper blu pistons). New seals and gaskets, a few bushings, Transgo Separator, LB-1 boost valve, Corvette Servo, GM longest pin & torque converter (Recon)

Before I put the new harness it was at max line pressure always every gear (215 psi). It would buck and rev the rpm and not shift to 3rd unless you floor it and the it would go to 4th and almost red line and the drop back down to about 4000 rpm

After different harness it is at 50 psi in all gears but will shoot to 100 psi with the pedal halfway down. It still is doing the same thing in 3rd and 4th.

It was throwing a lot of codes

Before internal harness & EPC swap

O2 Sensor Bank 2 codes
Random Misfire
P0748 EPC Circuit
ABS
and some Stop Switch (That I have not had time to check out what it is.

After Internal Harness & EPC swap it threw way more codes but did seem to fix the EPC code and the pressure normalized somewhat. I think this is due to the burn?? Stain looking spots in the harness plug I posted.

It now throws

​​​​​​Random Misfire Code
ABS
Stop Swiitch
Now I'm getting
Shift Solenoid Codes A & B Stuck OFF
PCM ROM codes P0605
P0752
PCM is seeing less than a 200 RPM difference between the rotational speed of the Torque Converter and the Transmission Input Shaft
P01870
Transmission Component Slippage
& More

The P0605 scares me.

I'm just getting done with my shift this week going to see what I can find out this weekend and then reThink things.

Bob