ULTM8Z

So I'm swapping over to a 4L80E after my 700R4 bit the dust a few months back.

Question is, what do I do about the VSS? Has anyone had any experience with a 4L80E into a 90-92 TPI car?

RBob

iTrader: (1)

The TOSS (transmission output speed sensor) is a 40 tooth ring with a mag pickup. Need to get that to a 2 - 4 K PPM mag or optical/digital signal. If you are using any of the ECMs pulse stream outputs will need the magnetic input to the ECM.

For an optical/digital signal a stock GM DRAC will work (strap programmable).

For either optical or magnetic a Dakota Digital SGI-5 box works (user push button programmable).

Depending upon which controller you use it may have an output you can use.

RBob.

MrWillys

Give me your tire size and rear gear and I can tell you what value to reassign your VSS to. The 4L80E measures the rotations of the shaft vs the simple 4 PPM of the 700R4. I've done this for others and it works.

ULTM8Z

Ok, that when over my head at about SR-71 crusing altitude!

Basically what I'm looking for is how to take the purple and yellow wires on the EFI harness (that used to plug into the TH700R4 VSS) and "plumb" them into the 4L80E.

I know there is an output shaft speed sensor... can I tie them into that sensor?

ULTM8Z

I have a 285/40-17 tire, which works out to just about 26" tall with a 3.42 axle ratio.

MrWillys

The stock AUJP BCC is set at 4007 PPM. Change that value to 95360. The hex will most likely round it off but it will be close enough. Give me your bin if you need help.
Scott


One of my friends is a CEO of an Aerospace company and he built me a spread sheet just for this calculation. It was for this Truck.

ULTM8Z

Thanks. Programing the bin is the easy part. Figuring out how to hook up the ECM to the 4L80E seems it could be the challenge.

ULTM8Z

I'm still confused on what to do with the purple and yellow wires (VSS Low and High, respectively) on the EFI harness once the 4L80E is in the car.

The transmission TCU harness is self contained and has the input and output shaft speed sensor hook ups for the transmission.

But the thing is, I need a signal to replace the signal from the 700R4 VSS in order to go to the 7730 ECM.

MrWillys

Polarity does not matter and it is still an AC wave. The only thing that changes is the value in the bin.

ULTM8Z

Ok, so just splice the purple and yellow wires into the two wires on the 4L80E output shaft speed sensor. Then simply adjust the bin to compensate.

MrWillys

You're on it.

ULTM8Z

Schweet! Almost too simple!

Street Lethal

iTrader: (16)

Post your results ULTM8Z, k...

ULTM8Z

Yep. One thing about this 4L80... it's been converted into a six speed.