A little help with pinning VSS.

[Astro]

Hey all,

Converting my 96 k1500 4L60e to a 96 4L80e. I have most of the pinouts figured out, but I have one question. I discovered that the VSS for the 4L60e is actually on the transfer case. This kinda threw a wrench into what I thought I had to do with the pinouts on the 0411. It thought it was going to be easy because I expected a sensor to be on the tranny.

To my question,

Since the 4L80e has two VSS sensors, do I just re-wire the VSS from the transfer case into the 80 and leave it sitting there, unused on the transfer case? Based on the pinout spreadsheet I have from when I converted to the 0411, I have 4 wires to use on VSS for front and rear sensors. There WERE two other wires that were spliced together and inserted as a single signal for VSS as well, but there doesn't seem to be any instruction or explanation other than that. The spreadsheet calls out for one set of VSS wires to be 80 specific and the others to be 60 specific and then those two that are tied together.

Anyway, I may be over thinking it, but that's where I'm stuck. Do I leave the transfer case VSS out of the loop and tie those wires into the 80? Any input would be greatly appreciated! Attached pinout below.

Thanks guys!

 

[b454rat]

4L80 uses t-case VSS for a 4wd, or on a 2wd just in front of the tail housing. 4wd's have a plug there....

 

[Astro]

4L80 uses t-case VSS for a 4wd, or on a 2wd just in front of the tail housing. 4wd's have a plug there....

Hey B454, thanks for the reply. I'm not sure I understand.

So the 4l60e transfer case, which I'm trying to mate to the 80e, has a speed sensor on it. The 4l80e has two speed sensors on it as well, totaling three speed sensors after everything is installed.

So I'm not sure which two to use, since I only have wiring for two.

I should add that the 80 is a 4wd 80 and has the two sensors. Not sure if that helps

 

[NickTransmissions]

Hey all,

Converting my 96 k1500 4L60e to a 96 4L80e. I have most of the pinouts figured out, but I have one question. I discovered that the VSS for the 4L60e is actually on the transfer case. This kinda threw a wrench into what I thought I had to do with the pinouts on the 0411. It thought it was going to be easy because I expected a sensor to be on the tranny.

To my question,

Since the 4L80e has two VSS sensors, do I just re-wire the VSS from the transfer case into the 80 and leave it sitting there, unused on the transfer case? Based on the pinout spreadsheet I have from when I converted to the 0411, I have 4 wires to use on VSS for front and rear sensors. There WERE two other wires that were spliced together and inserted as a single signal for VSS as well, but there doesn't seem to be any instruction or explanation other than that. The spreadsheet calls out for one set of VSS wires to be 80 specific and the others to be 60 specific and then those two that are tied together.

Anyway, I may be over thinking it, but that's where I'm stuck. Do I leave the transfer case VSS out of the loop and tie those wires into the 80? Any input would be greatly appreciated! Attached pinout below.

Thanks guys!

I responded to your question on the GM square body forum but saw this and realized it was your question but your user name over there is different. Anyway, what year 4L80E do you actually have? The 1994+ 4L80E 4x4 units omitted the rear speed sensor from the transmission as it moved to the TCase as of that model year. If you have a 91-93 4x4 4L80E then it will have both speed sensors (some early 94 units also did have them supposedly but they were few and far between).

Post pictures of the speed sensor-side as well as the cooler line fitting side of your 4L80E here.

Regardless, follow your instructions for 4L80 4x4 swaps - for 96, I would think they would have you use the T-case speed sensor location and the 4L80E's input speed sensor.

Unrelated but how are you adapting your 4L80E's output shaft (32 spline) to work with your 4L60E's transfer case input which is 27 spline?

 

[Astro]

Hey Nick, yeah I posted it to several places to see if I could get a quick hit. Thanks for answering, lol.

Funny enough as it is, I JUST discovered the spline shafts are different and came on to the forum and found your post.

So, I wasn't expecting that and am not sure what to do about it. It definitely puts a wrench into everything. Now I have everything out and can't put it back in and I've all but exhausted the funding for this project .


About the 80, I bought it from Ebay from a supposed 1996 K2500. It came with two sensors on the driver's side It seems like the t-case one is essential so I can make sure to wire that one in. Is the front or rear sensor the input sensor?

Thanks for your help again, man.

 

[Astro]

I'm also running into another problem.

I can't seem to get the right flex-plate. I found a pioneer (FRA-161) one that seemed to have the right dimensions, but the ID of the hole where the crank fits in is like .005 too small. Otherwise it seemed good, 168 teeth and 14.125" OD.

So what's weird is it's listed as having a 2" ID hole, but it's actually between 2.055-2.060. Even the OEM one is ~2.067. Crank is ~2.065. That's a whole 1/16 of an inch.

Anyway, I'm toying with the idea of "modifying" it, but I really don't want to possibly mess with the balance of the plate, although I may be overestimating the difference .005 might make. Or I could heat it up to expand the hole a bit during install.

Do you happen to know the flex plate that mates to this 80 and an L31, if it's not the FRA-161? Or would it be ok to just open the whole a bit?

 

[NickTransmissions]

I'm also running into another problem.

I can't seem to get the right flex-plate. I found a pioneer (FRA-161) one that seemed to have the right dimensions, but the ID of the hole where the crank fits in is like .005 too small. Otherwise it seemed good, 168 teeth and 14.125" OD.

So what's weird is it's listed as having a 2" ID hole, but it's actually between 2.055-2.060. Even the OEM one is ~2.067. Crank is ~2.065. That's a whole 1/16 of an inch.

Anyway, I'm toying with the idea of "modifying" it, but I really don't want to possibly mess with the balance of the plate, although I may be overestimating the difference .005 might make. Or I could heat it up to expand the hole a bit during install.

Do you happen to know the flex plate that mates to this 80 and an L31, if it's not the FRA-161? Or would it be ok to just open the whole a bit?

Pull out the rear 'speed sensor' on the transmission (8mm socket on the bolt) - I bet it's just an o-ringed plug and not an actual speed sensor...If you do, shine a flash light into the hole - you should see just the rear planetary carrier without the silver-colored reluctor wheel that the 1994+ 2WD 4L80Es all have but the 4WD versions lack.

I'd prob go to the junk yard and find a good-used, compatible t-case = you will need to research what would have to be done to integrate it into the rest of your truck's drive train. PTAC and others make a specialized output shaft for the 4L80Es for swapping into a 4L60E-equipped 4x4 w/the NP246 or like-kind t-cases but you'd have to tear the entire 4L80E transmission down to install it so not your first option unless you're familiar with how to do that sort of swap (basically, you'd be rebuilding the transmission at that point). My video series does show you how step by step but you'd need some tooling and money for rebuild kit and other things.

Flex plate - again, junk yard is your friend. Just find one in a 2500 or 3500 series truck or van - chances are it came w/a 4L80E (you can check the glove box for the RPO 4L80E RPO code, MT1).

I'd take the pan off of that 4L80E to make sure there's nothing in it that would be worrisome (burnt clutch material, metal shavings, etc). Also consider replacing the wiring harness as those are notorious for going bad, putting the vehicle into limp mode. Physically inspect and ohm out the solenoids with a multimeter as well, just to be sure.

 

[Astro]

The one I pulled from the rear turn out to be a sensor as well. And it's little metal bracket is corroded exactly in the same way as the front one leading me to believe they have both been there from the beginning. I installed new ones two days ago.

I mean, it should be fine if I leave the rear one out of the loop right? Just do the front and the one on the tcase.

 

[NickTransmissions]

Yes, leave the rear sensor out...There were a handful of those 4x4 units w/two speed sensors through 96 but im not sure of all the models that had the sensor. Also, perhaps its more common that i thought.

 

[Astro]

Copy, I'll do that.

As far as the flex-plate, I think I'm going to make it work.

I've found a couple t-cases I can grab off E-Bay that have decent mileage. The only thing that sucks is I'm going from a known great condition one to an unknown. I guess I did that with the tranny too. I mean they were both tested and verified working, but you know what I mean. If it isn't new, there's always that risk. It is what it is.

While under the truck I wire loomed everything anew. Got all the harnesses together nicely. Also got new sets of bolts for lots of stuff.

By the way, my wife says thanks for your help as well =D It's rare you get someone the sticks with you through a process.