4L80e to 208 or 241 questions.

[ZooMad75]

The guy I was trying to help sell his 6.2 diesel stuff is proceeding with his L29 vortec swap. We did a trade of transmissions so I ended up with a Nv4500 and he got the extra 4l80e I ended up with.

His burb had a 208 backing up the stock 700r4 so at minimum it needs a 32 spline input to run behind the 4l80e. A switch on the shifter would handle the 4lo input to the pcm, but the mechanical speedo of the truck will be the issue. We are trying to stay away from changing clusters and the trans is late enough (98) that I bet it's missing the reluctor gear for the rear oss position on the trans since it was out of a 4wd truck.

So in doing some research I found a couple of inline adapters that create a digital output off of the cable. I don't know if this would work because I keep reading about different values for the pulse per mile. What does a stock gm controller need to see? 1000 ppm or 8000ppm

We've talked about going 241 but to stay with the cable speedo we are in the same boat as the 208 his has now. If he went with a electric speedo 241 he'd have to to a 90-91 cluster and drac module which isn't easy to find either.

Any ideas on the adapters? Anybody use one for the vss signal to a 4l80e?

 

[Capt Ron]

 

[Bent77]

I thought @mrk5 did something weird

 

[imiceman44]

The guy I was trying to help sell his 6.2 diesel stuff is proceeding with his L29 vortec swap. We did a trade of transmissions so I ended up with a Nv4500 and he got the extra 4l80e I ended up with.

His burb had a 208 backing up the stock 700r4 so at minimum it needs a 32 spline input to run behind the 4l80e. A switch on the shifter would handle the 4lo input to the pcm, but the mechanical speedo of the truck will be the issue. We are trying to stay away from changing clusters and the trans is late enough (98) that I bet it's missing the reluctor gear for the rear oss position on the trans since it was out of a 4wd truck.

So in doing some research I found a couple of inline adapters that create a digital output off of the cable. I don't know if this would work because I keep reading about different values for the pulse per mile. What does a stock gm controller need to see? 1000 ppm or 8000ppm

We've talked about going 241 but to stay with the cable speedo we are in the same boat as the 208 his has now. If he went with a electric speedo 241 he'd have to to a 90-91 cluster and drac module which isn't easy to find either.

Any ideas on the adapters? Anybody use one for the vss signal to a 4l80e?

The smurfmobile had a doubler with a 205 and to put Dakota digital gauges Aaron did use one of those modules hooked up to the 205 speedometer cable output.
It works well

 

[ZooMad75]

The smurfmobile had a doubler with a 205 and to put Dakota digital gauges Aaron did use one of those modules hooked up to the 205 speedometer cable output.
It works well

I think it should work and from what I've read they are pretty good quality. I just don't know if they generate the correct pulse per mile that the stock pcm needs to see.

I'm still surfing the web for details but if anybody that has been through the same thing let me know.

 

[6872xtc]

I think it should work and from what I've read they are pretty good quality. I just don't know if they generate the correct pulse per mile that the stock pcm needs to see.

I'm still surfing the web for details but if anybody that has been through the same thing let me know.

I don't know if they have changed the PPM, but I am fairly certain that the Dakota digital unit doesn't have the proper number for the ECM. I know that @500$k5 looked into them years ago when doing a couple of EFI swaps. Maybe he will remember what he found out.

 

[ZooMad75]

I don't know if they have changed the PPM, but I am fairly certain that the Dakota digital unit doesn't have the proper number for the ECM. I know that @500$k5 looked into them years ago when doing a couple of EFI swaps. Maybe he will remember what he found out.

After doing more digging today at work and at home I've come across some options. The main being a signal interface from Dakota Digital. The reason being is most of the digital adapters that pull a signal off of the speedo cable generates a value different than what the GM PCM is looking for. From what I'm finding it's 128,000 ppm is the target number for the GM pcm.

Interface from Dakota

Here's the thread that mentioned it

This would be the actual adapter for the speedo cable.

VSS signal generator

So if what I've found is correct, then using the signal generator and interface from Dakota Digital should satisfy the GM PCM. Does anybody see something different? Is the 128k ppm right?

 

[Capt Ron]

I bet it's missing the reluctor gear for the rear oss position on the trans since it was out of a 4wd truck.

Watching for a possible future project. Would it be an option to add a reluctor gear back to the transmission?

 

[ZooMad75]

Watching for a possible future project. Would it be an option to add a reluctor gear back to the transmission?

That is a possibility, but I had my trans guy rebuild this one and I'm not really excited about tearing it down again to install it. The other issue is when you use that output the value won't be right when in 4Lo.

 

[mrk5]

My crew cab had a speedo cable. When I swapped the 4l80e in I added an electric output sensor to the NP205 rear housing. Some people do it themselves, or you can have ORD set it up for you. I ended up using a GPS spedometer since I'm not using the factory dash.

In my research before doing the swap, I read that some people have found a reluctor gear in the rear spot of a 4wd 4l80e. I think it was the earlier years that tended to have them. A lot of people use a 2wd 4l80e so they have the speed sensor, but as @ZooMad75 said it won't account for 4lo. With the standalone controller I use, you have to tell it when you are in 4lo. Some people felt like it was fine running the transmission without it knowing you were in 4lo, but I can definitely tell a difference when I forget to tell the controller I'm in 4lo. I don't think it hurts anything, it'll just rev way the hell up before upshifting - if it ever does.

I know it's an extra expense, but I really like having the standalone controller. It gives me a lot of options I wouldn't have otherwise, for instance dealing with 3 different low ranges. Plus it will display speed and trans temperature. It also has an output speed signal for an electric speedo. You can change the signal output type as well.

 

[ZooMad75]

Thanks for the input @mrk5 . Since this isn't my build I'm not the one calling the shots. He wants to keep the cable speedo. He's admitted to me yesterday that he is over his head on what the swap is needing for technical knowledge. He's been leaning on me, Larry and our buddy Bill pretty hard with questions of what to do. I'm just trying to get him to the most simple solution that will satisfy the stock cluster and the stock pcm for the trans control.

So the plan is using his existing 208, get a 32 spline input gear. Use both Dakota digital devices and dial it in to work with the stock pcm. Any other way forces using a 241 or 205 with the electric vss sender, a 90/91 electric speedo cluster and drac module. By going this way he's reusing the t-case and cluster and saving cost on getting more stuff.

 

[john in south tx]

Hey @ZooMad75
How’d that project go? We’re almost done with about the same thing:
‘88 k5 w/ np208, 4L80E, 5.3
Dakota Digital SEN-01-4160 Pulse Generator and SGI -100BT Signal Interface
You remember which output you used (ppm)? Any other advice for us?

 

[john in south tx]

Oh, the SPD+ and SPD- aren’t used, right?

 

[centexk5]

I've got some mechanical questions for a 4l80e to 208. Other than the 32 spline input for the 208, is there another adapter I need? Does the transmission mount need to be moved or modified? Not worried about the control, I've got that taken care of with the holley terminator.

 

[obijuank5]

The np208 physically mounts up like OEM if the 4l80e had a 241 or the borg warner on it. Probably many more but thats getting too new for me to know.
Its an excellent fit.

 

[john in south tx]

Yeah, and everything lined up after moving the motor mounts a bit.

 

[ZooMad75]

Hey @ZooMad75
How’d that project go? We’re almost done with about the same thing:
‘88 k5 w/ np208, 4L80E, 5.3
Dakota Digital SEN-01-4160 Pulse Generator and SGI -100BT Signal Interface
You remember which output you used (ppm)? Any other advice for us?

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Honestly, that setup has turned into a giant pain in the ass. We got it working but dialing it in has taken hours of fiddling while driving it.

Here's the main issue. Calibrating the Dakota box to the point where the reading on the ecm for speed is accurate to actual speed the trans shifts late and lazy. Going the other way to get the trans shifting at the right time and feel right has the ECM 20 mph fast to actual speed.

While that may not sound like a big deal, when the ECM speed limiter kicks in at 90mph, the truck was essentially stuck going no faster than 70mph.

It's at that point my patience hit a brick wall. I could have gone over stuff with the Dakota folks. We haven't had the time to pull that off.

We have talked to Howell that built the harness and did the tune. They advised with a change in the tune we could use the vss signal generator direct to the ECM with an update to the ECM calibration for what the Dakota device puts out without the box.

Option B is installing a tone ring and stock gm vss sensor to the 208 with a kit from Walters performance. From there we would clone a 90/91 stock setup with a drac module and electric speedo cluster since the cable would be eliminated.

Option C is similar but ditching the 208 completely for a 241 with vss output. We would still add the 90/91 electric speedo cluster and drac module.

I haven't talked to my buddy for a while on which way he wants to go. I'm leaning to just running the Dakota adapter straight to the ECM and getting it tuned to use it.

 

[Tnsejed]

Lol, nevermind. I didn't read all the posts and timeframe.

 

[john in south tx]

That sux @ZooMad75. Thanks for taking the time to send all that info. I guess after coming this far, gonna have to try it as dakota suggested this am and hope for the best. This is what they told me to do (hopefully this helps you, too):
IGN - ignition power
GROUND - to chassis
SPD+ - nothing
INPUT - white from pulse generator
SPD- - black from pulse generator
OUT 1 - nothing
OUT 2 - nothing
OUT 3 - to High speed wire from ECM
The rest of the terminals stay empty.
Notes:
Needs to be set to L-H
Also said to cap off the Low speed wire from ECM
For calibration, they make it sound like the Bluetooth method is easy.
Wish us luck!

 

[john in south tx]

Took a bit to get to it, but I wanted to report back that we did recently get it to shift properly. If I can be of any assistance to anyone, do let me know. I’ll try my best from what I learned.