1996 4l80e, fresh rebuild, no reverse - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
Home Forum Market Place Garage Tuning Library DTC Tool Register Vendors
Go Back   Diesel Place : Chevrolet and GMC Diesel Truck Forums > GM Transmissions > 4L80/85E Transmissions. 6L90 Transmission
Register FAQ Forum Rules My Replies My Threads Mark Forums Read Advertise

4L80/85E Transmissions. 6L90 Transmission Discuss the 4L80/85E transmissions found in the 6.2/6.5L equipped vehicles and Duramax equipped vans. 6L90 discussion.

DieselPlace.com is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 04-23-2017, 11:43 AM   #1 (permalink)
Heathmzwahlen
Low Boost
 
Join Date: Apr 2017
Posts: 5
iTrader Score: 0 reviews

1996 4l80e, fresh rebuild, no reverse

Hey all, I'm new to the forum so bear with my stupid if I come across that way.
Currently I'm having some 4l80e issues on a 96 Burban 2500. So let me lay out the issue and what I've currently done.

The current problem I'm having is the truck will not move in reverse. I've searched thru the forum and have found great info, just nothing I wanna hear...

So: I just had a rebuild done and put it back in and it moves and shifts great in all forward gears including 1st - 3rd and engine brakes appropriately, but no reverse. Trans pressures are at 75psi at idle in all forward gears and 175ish at 1500 rpms . Reverse is at 100psi at idle and 280ish when I "blip" the gas...so maybe 1100 rpms or so. I am also getting about 1-2 gallons per minute of fluid flow. Just before I put this back in the truck, I replaced the radiator and the add on Transcoolers along with the cooler lines.
I've also replaced the rear servo and pin, epc selonoid, new torque converter.

I did notice that the rear servo looks to be out of a late model 4l80 and I thought that a1996 model would still be using the early model version.(flat cover vs rounded cover) . Could that be my issue?

Offline  
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-23-2017, 03:02 PM   #2 (permalink)
davester
Diesel Prodigy
 
Join Date: May 2015
Location: Canada
Posts: 4,441
iTrader Score: 0 reviews

Did you do the rebuild or did you get some shop to do it?

If some shop, why not drag it back to them to get reverse working?

If you did it yourself, did you get the right length reverse pin (the pin that clamps the reverse band)?

Did you test all the electrical stuff (that the solenoid works, and that the internal harness has continuity and the right pins are getting powered on the plug to the transmission for reverse? Any codes?

__________________
2004 GMC Sierra 3500 C&C, added 4WD, 6.0L gas, Extended Cab, SLE, Transgo 4L80e-HD2 kit installed
Whee! Dually Club Member #1109
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 11:18 AM   #3 (permalink)
Heathmzwahlen
Low Boost
 
Join Date: Apr 2017
Posts: 5
iTrader Score: 0 reviews

Rebuilt 1996 4l80e - No reverse

Davester, Thanks for the reply...in response to your questions:

I had a shop rebuild it but they are 100 miles away, so before I yank this pig back out I want to make sure I'm covering any issues I can resolve without pulling it.

I've checked all the electrical connections and harness's. I did get the correct reverse Servo pin, but the piston looks the same as what comes out of the newer model 4l80E...I had thought the 96 model had a different servo casing and the piston was flat instead of rounded. If the rebuilder had put in a newer version of the servo, the pin would be shorter than the older, right?

I had also heard that if the PCM/TCM was getting input from the Vss incorrectly (over 8mph) that it would not allow the reverse to engage. But I'm getting the correct pressures when I move the selector to reverse(290psi) and when I unplug the harness to bypass the PCM/TCM, all line pressures go high (380psi) and I still get no engagement. So, short of maybe a Center bolt being bad or a Reverse band incorrectly installed, I don't know what else to look for??? Maybe a Torque converter not seated properly?? But wouldn't that show by having a low fluid flow or low pressure??
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-24-2017, 11:26 AM   #4 (permalink)
Heathmzwahlen
Low Boost
 
Join Date: Apr 2017
Posts: 5
iTrader Score: 0 reviews

Oh, I also probably need to mention that there is nothing electronic involved when you are in reverse(solenoid wise) on this year 4L80E. Reverse actuation is mechanical which is why when you unplug the Trans Harness the system defaults to high pressure and reverse and 1st should work...or maybe it's reverse and 3rd?
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 02:51 PM   #5 (permalink)
davester
Diesel Prodigy
 
Join Date: May 2015
Location: Canada
Posts: 4,441
iTrader Score: 0 reviews

From what I understand, after rebuilding my 4l80e and reading several pdf's on rebuilding it (mine is an '06, so there are some internal bits slightly different from yours), that the pin that presses against the reverse band needs to be just the right length (it comes in multiple lengths). There is a special tool for measuring what length it should be, and there is at least one other way to at least ballpark the measurement if you don't have the tool. My reverse band wasn't particularly worn and reverse was working fine, so I reused both the band and the pin.

Having only worked on the one transmission, I haven't seen the bits for older transmissions like yours to compare.

Short of the torque converter outright failing, it's unlikely to be the problem. If it's not inserted correctly into the transmission, you generally have to bust things to install it into the vehicle, as the converter winds up sticking out too far, and presses against the flex plate before the transmission touches the engine.
__________________
2004 GMC Sierra 3500 C&C, added 4WD, 6.0L gas, Extended Cab, SLE, Transgo 4L80e-HD2 kit installed
Whee! Dually Club Member #1109
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 02:57 PM   #6 (permalink)
Heathmzwahlen
Low Boost
 
Join Date: Apr 2017
Posts: 5
iTrader Score: 0 reviews

K...I'm pretty sure the torque converter was installed properly as I had about a 3/16 gap between it and the flexplate. One more question: I've noticed the gear shift selector(in the cab) will not move down to 1st or even 2nd...it seems to bottom out at 3rd. I'll be replacing that, but I assume that since the tranny is actuating right as I select P-R-D-3 that this is probably not the actual issue...Just one more thing to get fixed.
__________________
There's no cure for Stupid...save Death.
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 08:14 PM   #7 (permalink)
davester
Diesel Prodigy
 
Join Date: May 2015
Location: Canada
Posts: 4,441
iTrader Score: 0 reviews

Depends on where the problem is. If you take off the shift cable from the lever on the transmission, can you move the lever between all the positions (PRND321)?

Because it's possible to install at least one of the rods in the valve body incorrectly, so the shift lever doesn't have the full range of motion, as well as also preventing it from shifting properly.
__________________
2004 GMC Sierra 3500 C&C, added 4WD, 6.0L gas, Extended Cab, SLE, Transgo 4L80e-HD2 kit installed
Whee! Dually Club Member #1109
Offline   Reply With Quote Quick reply to this message
Old 05-05-2019, 03:53 PM   #8 (permalink)
Art4med
Glow Plug
 
Art4med's Avatar
 
Join Date: Jan 2016
Location: Near FtBenning
Posts: 220
iTrader Score: 0 reviews

Quote:
Originally Posted by Heathmzwahlen View Post
Oh, I also probably need to mention that there is nothing electronic involved when you are in reverse(solenoid wise) on this year 4L80E. Reverse actuation is mechanical which is why when you unplug the Trans Harness the system defaults to high pressure and reverse and 1st should work...or maybe it's reverse and 3rd?
So if a 1996 and no reverse, its either the pin’s too short or I *must rebuild the direct pack?
__________________
1996 Chevrolet K3500 6.5L turbodiesel, VIN"F", DS4, dually 4x4, standard cab/chassis on 31403 frame with Wheeled Coach TypeI Ambulance module; 4L80-E trans on 3.73:1 rear, widetrack; 53K mi; GVWR:12k, HD front suspension. Work and replaced: Serpentine belt and idler, PMD @9ohms relocated to grille, oil cooler/lines and fittings, 2x 105A alternators, fusibles, starter, CDV (washed), coolant flush, ignition relay, rear shoes and front discs, pintle seal, added grounds (cleaned all AGAIN); WSS, VSS, TISS, TOSS, OPS, xover ECTS, dual 180° thermo’s, TOYO tires, Lower ball joints, shocks, stabilizer links front/rear, 93 lift pump, batteries, rebuilt 4L80E; AmbuModule is a WIP (lots to go!)
Proven: “You can only afford this vehicle if its worked-on yourself”, a labor of love that is best-attended with the help gratefully-found only here at DP!
Whoever mixed peanut oil into wiring insulation? Hmmnnn?
3500 Dually Club member #1100
Offline   Reply With Quote Quick reply to this message
Old 05-05-2019, 10:24 PM   #9 (permalink)
johnH123
Diesel Apprentice
 
Join Date: Jun 2018
Location: IN
Posts: 349
iTrader Score: 0 reviews

Does it engine brake in manual first? do you have 3rd gear?

also, limp mode is 2nd gear, and 2nd is activated by both solenoids being off. In order to get forward 2nd gear, you need forward clutch and 2nd clutch engagement.

Reverse is different. IIRC solenoid A is off and solenoid B is on, which applies only the 3rd clutch. in order to get reverse, you also have to have band engagement, and since there is no reverse solenoid, i assume that band engagement is done with the manual valve. Just throwing this all out there in case someone needs it.

so to answer your question @Art4med, if you have 3rd gear in forward, and a no reverse condition, you have a rear band issue. either it's too worn or the pin is too short. HOWEVER, if you have no 3rd gear, and no reverse, the direct is screwy. Do you have any codes? start there because codes will really help narrow this down as well. If you do have codes, please report them back here.
__________________
1993 K3500- 4x4, single cab/long bed, single rear wheels, 4.10 rear end, F vin, GM3 turbo, Nv4500 manual with Luk clutch and single mass conversion, 3" front lift/level, factory red interior.

A few mods: 3" straight pipe, Bosch boost gauge, Bosch glow plugs, Draw-tite class 5 hitch. Hi-flow water pump, 94+ radiator and coolant tank conversion, kept the original single thermostat setup (at least for now).


Gone but not forgotten: 2001 silverado 2500hd CC/SB, 4x4, 6.0 vortec, 229k miles when I traded it.
Offline   Reply With Quote Quick reply to this message
Old 05-10-2019, 11:31 AM   #10 (permalink)
Art4med
Glow Plug
 
Art4med's Avatar
 
Join Date: Jan 2016
Location: Near FtBenning
Posts: 220
iTrader Score: 0 reviews

@johnH123 @davester : I have no codes stored. I have no reverse nor third in D, tho checking MANUAL3 this morning. There is noise and oil in the thru connection. Only 53K. Have not checked pressures.
The tranny shop [in high regard but 40 miles away] sez “must rebuild” by phone. Of course.
While I was *considering doing this rebuild myself (despite my low competence), I need dependability here. So I’m leaving it to the shop while I’m away for ten days. ??

__________________
1996 Chevrolet K3500 6.5L turbodiesel, VIN"F", DS4, dually 4x4, standard cab/chassis on 31403 frame with Wheeled Coach TypeI Ambulance module; 4L80-E trans on 3.73:1 rear, widetrack; 53K mi; GVWR:12k, HD front suspension. Work and replaced: Serpentine belt and idler, PMD @9ohms relocated to grille, oil cooler/lines and fittings, 2x 105A alternators, fusibles, starter, CDV (washed), coolant flush, ignition relay, rear shoes and front discs, pintle seal, added grounds (cleaned all AGAIN); WSS, VSS, TISS, TOSS, OPS, xover ECTS, dual 180° thermo’s, TOYO tires, Lower ball joints, shocks, stabilizer links front/rear, 93 lift pump, batteries, rebuilt 4L80E; AmbuModule is a WIP (lots to go!)
Proven: “You can only afford this vehicle if its worked-on yourself”, a labor of love that is best-attended with the help gratefully-found only here at DP!
Whoever mixed peanut oil into wiring insulation? Hmmnnn?
3500 Dually Club member #1100
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Diesel Place : Chevrolet and GMC Diesel Truck Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

PLEASE READ! You must check your email inbox for the confirmation link to complete registration. Please check your spam box if you do not see the email in your inbox.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in


Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
4L80E Rebuild and Improvement paleyjim 4L80/85E Transmissions. 6L90 Transmission 70 12-12-2019 12:28 PM
4L80E Slipping Reverse DieselBurban99 4L80/85E Transmissions. 6L90 Transmission 3 10-28-2016 10:13 PM
Rebuild kit for 4l80e davester 4L80/85E Transmissions. 6L90 Transmission 3 10-25-2016 10:59 AM
Question: 1996 6.5 diesel 4l80E to 4l60E conversion racerx944 6.5L Diesel Engine 18 10-03-2016 08:14 PM
TPMS Rebuild Kits | What You Need to Know Discount Tire Discount Tire 7 12-16-2015 10:31 AM


All times are GMT -4. The time now is 12:28 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Shoutbox provided by vBShout v6.2.1 (Lite) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
© AutoGuide