What does a 4L80E need to function?

[SimpleGreen]

So, my buddy has a 1994 GMC 1500 (single cab, short bed) with a 468BBC in it, a mild cam, and a very small 600CFM carb on it. It just gets him back and forth to town when his girlfriends Mustang GT isn't available, It currently has a TH400 trans behind it. He has a later model 4L80E, a complete wiring harness, and a PCM to it as well. He wants to put it behind the BBC so he'll have an over drive gear.

What I need to know, it what does the PCM need to operate the trans? I want to say its the VSS signal, TPS signal, and MAP signal for engine load? Is there any reason why I couldn't setup the MAP and TPS on the big block and the PCM shift the trans properly? I think it also just needs a TQ lock signal like my 4L60E did in my step side did.

Thanks.

[94Stroker]

You are going to need an aftermarket controller. Like TCI or Compushift.
I don't know how an oem computer could control it without controlling the engine as well.. They are
interlinked as far as I know

[oldred95]

It should work just the same as a 4L60E does with a carburetor. Engine speed, vehicle speed, map sensor, TPS, and coolant temp should be all you need. Honestly I don't think the PCM will know the difference because physically there is an engine there and if the proper sensors are hooked up as far as the PCM concerned its there and running. You might get a few DTCs for stuff like EGR and evap purge and this and that, piddle stuff, but it should still control the transmission just fine.

[SimpleGreen]

It should work just the same as a 4L60E does with a carburetor. Engine speed, vehicle speed, map sensor, TPS, and coolant temp should be all you need. Honestly I don't think the PCM will know the difference because physically there is an engine there and if the proper sensors are hooked up as far as the PCM concerned its there and running. You might get a few DTCs for stuff like EGR and evap purge and this and that, piddle stuff, but it should still control the transmission just fine.

See, that's what I was thinking. The PCM could care less if the engine is there so long as it gets the info it needs for the trans. We're going to slim this harness down and try it out. I see no need to line TCIs bank account for their overpriced BS when an electrician and a mechanic can put their heads together and re-use GM stuff laying around for our purpose. Only other thing I can think of, are there any issues to be run into with trying to bolt a 2004 4L80E to a run-of-the-mill big block Chevrolet?

[whitelightnin92]

yeah you need a DRP to the computer for the trans to function. tps, map, vehicle speed thats about it

[oldred95]

The bolt patterns are all the same except for the bolt at high noon probably isn't used on the old big block like it is on the LSX stuff.

No offense but some of the worst automotive related electrical work I've seen done was done by electricians. They think break out boxes, solid core wire and wire nuts is the way to go for everything.

[SimpleGreen]

The bolt patterns are all the same except for the bolt at high noon probably isn't used on the old big block like it is on the LSX stuff.

No offense but some of the worst automotive related electrical work I've seen done was done by electricians. They think break out boxes, solid core wire and wire nuts is the way to go for everything.

Cool.

Well it turns out, I do 12V electrical work on emergency vehicles (about 3 years now)...and even on our 110V stuff we would be beat with a hose if we used wire nuts :lol:

[gregs78cam]

Everything you need to know should be here:

http://mattw.dyndns.org/4L80E/

[Jeff6.0]

No offense but some of the worst automotive related electrical work I've seen done was done by electricians. They think break out boxes, solid core wire and wire nuts is the way to go for everything.

I'm an electrician and I agree with you. I admit there are a few wire nuts on my truck... three years ago they were gonna be a temporary connection but...

[GreaseDog]

yeah you need a DRP to the computer for the trans to function. tps, map, vehicle speed thats about it

What is a drp?

[whitelightnin92]

Distributor reference pulse