4L80E and NP241 speed sensor

[wheels87k5]

I am swapping in a Vortec 454 7.4L. I had the harness and PCM reworked by Team208Motorsports. The transmission is the 4L80E. It is a 2WD tranny but I made the changes to 4WD. It has two speed sensors on the side of the tranny. Is this going to provide the signal needed to the PCM? Or is there some other type of part needed to get this engine to start and run?

When I had the 350 TBI, I used a speed sensor that hooked up to the NP241 to provide the signal to the speedometer, that sent the signal to the ECM. Wasn't sure if there is anything else since it was a 4L80E.

I am still a ways out on starting this engine, just wanting to know if there is anything I am missing once I am ready to get it rolling.

The second speed sensor (rearmost mounted) typically isn't used in 4wd applications since it would normally use the T-case output speed sensor as the input needed to the PCM for output speed.

Since my NP241 doesn't have the output speed sensor, it sounds like I would need to use both sensors from the 4L80E.

With the 350 TBI, the speed sensor that mounted to the np241 enabled the electronic autometer speedometer to work because they worked together with the sensor revs. It would then send the required signal to the ECM. I wasn't sure how the signal got to the L29 PCM except through the speed sensors on the 4L80E. I'm just trying to make sure I have everything necessary when it's time to start this thing and that it has the signal needed.

Wouldn't that screw you up when/if in 4wdLow? The transmission output and transfercase output would be at different speeds - the ECM would be seeing the transmission speed signal but that would not match the actual speed.

This is what I'm needing to find out. If what I have now will not work like needed, what do I need to do to correct it?

Do I need to add something to the NP241 so that it will be in sync?

Since my NP241 is the mechanical speedometer, will I need to convert it to electrical?

 

[ZooMad75]

With the 350 TBI, the speed sensor that mounted to the np241 enabled the electronic autometer speedometer to work because they worked together with the sensor revs. It would then send the required signal to the ECM. I wasn't sure how the signal got to the L29 PCM except through the speed sensors on the 4L80E. I'm just trying to make sure I have everything necessary when it's time to start this thing and that it has the signal needed.

This is what I'm needing to find out. If what I have now will not work like needed, what do I need to do to correct it?

Do I need to add something to the NP241 so that it will be in sync?

Since my NP241 is the mechanical speedometer, will I need to convert it to electrical?

My thought would be you need the output on the t-case. This goes into the second question you pose, only reading output at the trans will not be accurate in low range. I'd go for converting the mechanical output to electric. From there it's a matter of pulling the signal off of the drac module (stock for a VSS equipped square) to provide the output speed to the ECM.

 

[wheels87k5]

Then I'm confused........just a little more than usual, but according to this article on Pirate, it says to run the 2WD 4L80E as is. And not to use the T-case as the speed sensor.

https://www.pirate4x4.com/forum/chevy/1952482-4l80-rear-vss-location.html

Or am I reading it wrong. How do you see it?

 

[ZooMad75]

They can be done either way. GM does it both ways. 4wd gets the output speed sensor in the t-case, 2wd obviously don't have a t-case so they need to use the rear output in the trans. However, using a 2wd trans coverted to a 4wd rear ouput shaft you could use the rear output on the trans, but normally you would need an input to the trans/pcm controller to indicate 4lo is on.

The guy that did your harness and tune should be telling you how they have it set up to run. I'd check with him.

 

[rksjd8420]

You can use the transmission output speed sensor. The only problem with that is your speedometer will be off in low range. The factory setup that uses the transfer case output, grounds out a wire when you shift to low range. That sends a signal back to your computer that recalibrates your shift points. Make sure that wire is not hooked up if you are using the transmission output. Your engine and transmission will just think it is a 2 wheel drive. Waynehartwig on pirate in your link does the same thing as Josh and they both really know what they are doing.

 

[AJs72K5]

On my TCI controller for my 4L80, I used the rearmost of the two outputs on the trans for the speed sensor signal. I tried to use the 241 signal, but the controller didn’t like it (signal wasn't in the format the controller expected). Doing it this way will mean that 4-low will confuse the controller. Expect to have to shift manually in that use case

 

[454Sub]

I was curious of this as well.

Now that my 80e has a doubler, I don't feel like making ground switches for all the shifters just for an accurate speedo

 

[wheels87k5]

From the link above......and after further research:

{Waynehartwig: Put it between the Tcase and Trans. That way regardless of your driveshaft/road speed, the trans will always shift correctly.
Best is to convert the trans (or buy) to 2wd. ie put the VSS inside the trans. Some 4wd transmissions will actually have the code wheel inside and you just need to a speed sensor. Some don't have anything. Take the plug off and look inside to figure it out...
Bad thing about adding a 4lo wire and VSS on the end of the Tcase, is if you have a 4:1 Atlas. Or anything NOT 2.72:1....}

AND:

(Is there such thing as a 2wd and a 4wd tune fore the ECM, is that something I need to consider?)

{Waynehartwig: Nope. Well there is, but it won't matter once you move the VSS into the trans.
If an accurate 4lo speedo is important to you, have the speedo run off the VSS on the output of the tcase. Then it will be accurate and independent of the trans shifting.}

So.....

It looks like I should be able to use both sensors from the 4L80E and have all shift points. The speedometer will be ran from the aftermarket speed sensor off the NP241.

Once I get to that point, I will update everyone with how it ran and shifted. I'm also going to copy and paste this in my build thread.

 

[wheels87k5]

The guy that did your harness and tune should be telling you how they have it set up to run. I'd check with him.

I did reach out to Josh to get his input on the tune. I'll let you know what he says.

 

[Magikal]

I did this very swap into my k5. Pcm and harness reworked by Josh at team 208. Donor was a 1997 c3500. I had no issues with operation but mines off road only so I don't run a speedo. Come to think of it, I remember having the scanner hooked up while running and it read 50+mph when I was really doing 15 or 20 probably. Other then that, great swap. Josh really knows his stuff for performance.

 

[6.2Blazer]

I know the original post is pretty old, but will add in my comments just for people who may search for this answer in the future.

Friend of mine just did a 5.3/4L60E swap into his '93 K1500. He originally tried using a speed signal right off the transmission output based off of his web research (this required custom fab work on the trans). It acted all types of crazy when in 4 low. Not only the speedo being off but the shift points were way off also. Finally talked him into just tying into the VSS on the NP241 and everything works perfect now.

 

[wheels87k5]

Thanks for the replies.
Josh did a great job on my PCM and harness. Last time I talked with him......I said I would find out where he was and would bring the K5 to him for final adjustments. He agreed and can't wait to see it.
My NP241 is mechanical so no VSS. But I have a speed sensor that attaches to the NP241 to send a signal to the speedometer that is adjustable and accurate.
I am way behind on getting my K5 running. I'm able to do some work on it but limited with shoulder therapy and all the work that has showed up at my job. I thought I was going to get an offer to retire but that will have to wait until after September and possibly as late as December.
I will only use the 4L80E sensors for the PCM signal and not speedometer.

 

[Magikal]

I can relate. My build came to a screeching halt when I got diagnosed with congestive heart failure 3 months ago at ripe age of 42. Not obese. Doesn't run in the family. Healthy in every other way. No one can figure out why. Regardless, headed to stanford, ca next week for open heart surgery....

 

[wheels87k5]

Wow....Sorry to hear that. Go get it fixed and keep us posted. Prayers for a quick and speedy recovery.

 

[Magikal]

Thanks. Need all the support and prayer I can muster. Not thrilled about open heart surgery. Scared shitless actually....

Praying they can do it robotically vs conventionally. It's the difference between a few day or a few month recovery time

 

[Capt Ron]

I can relate. My build came to a screeching halt when I got diagnosed with congestive heart failure 3 months ago at ripe age of 42. Not obese. Doesn't run in the family. Healthy in every other way. No one can figure out why. Regardless, headed to stanford, ca next week for open heart surgery....

Thought and prayers are with you. Keep fighting!

 

[Magikal]

Thanks.

 

[crzna442]

I know the original post is pretty old, but will add in my comments just for people who may search for this answer in the future.

Friend of mine just did a 5.3/4L60E swap into his '93 K1500. He originally tried using a speed signal right off the transmission output based off of his web research (this required custom fab work on the trans). It acted all types of crazy when in 4 low. Not only the speedo being off but the shift points were way off also. Finally talked him into just tying into the VSS on the NP241 and everything works perfect now.

I know the original post is pretty old, but will add in my comments just for people who may search for this answer in the future.

Friend of mine just did a 5.3/4L60E swap into his '93 K1500. He originally tried using a speed signal right off the transmission output based off of his web research (this required custom fab work on the trans). It acted all types of crazy when in 4 low. Not only the speedo being off but the shift points were way off also. Finally talked him into just tying into the VSS on the NP241 and everything works perfect now.

Hi there, I’ve been scouring the internet trying to get answers on this. I’m doing a 5.3 /4L60e/NP 241c swap into a 1979 4x4 and even though I am not to this point yet I’m trying to plan ahead. Do you know how your friend tied into the VSS on the NP 241c? If not that’s ok just thought I’d check.