More stuff on swapping a 4L60e for a 4L80e

[Shannen Durphey]

<Content reduced>

Hello. I guess my first post didn't make it through.

Doug Bazarnic wrote:
> 
> >>The main electrical connector that interconnects the engine wiring harness
> >>to the transmission is not the same and there are different numbers of wires
> >>used (I don't know what they are all used for).
> 
> After reading the service manual, the main electrical connector on both
> trannys is the same.  

Your manual isn't telling you all you need if it doesn't say that
there have been 2 design connectors on the 4L80E, and while a unit for
a 1994 + pickup will have the newest design connector, there are still
transmissions in junkyards and overhaul shops with the old style part.

>However, the 4L60E has 2 more wires than the 4L80E.
> (The connector has lots of empty pin holes)   The 4L80E also has a
> secondary speed sensor unit, which would require running two wires up to
> the computer, that my wiring harness doesn't have.
> 
> >>There are two different PCM's that control the 4L80E. One comes on the
> >>diesel engines and the other for the gas engines.
> >
> >Yes, and there is a third PCM for turbo diesels, too! Each is (totally)
> >different and not interchangable. As well, there are two (at least) 4L80E
> >transmissions, the early and the late models. The TCM/PCM is different for
> >each, so that makes about five different TCM/PCM combinations!
> 
Forget the TCMs and the diesel PCM.

In GM's listing of calibrations for a 1995 1/2 ton 2wd GM pickup, 5.7l
and 4l60E, it shows a part number 16156395 computer.  Then it says
that part no is superceded by part no. 16197427.  Looking up a 3/4 ton
GM 2wd pickup w/5.7l and 4l60E, finds the computer part no is
16156930, superceded by part no 16197427.  And looking up 1995 3/4 ton
GM 2wd pickup, 5.7l and 4l80E, shows the PCM part no 16197427, and
notes that number replaces part no 16156395 and 16156930 computers. 
When looking up your calibration, BJYM/0102, I again find the
remanufactured ECM# is 16197427, which replace part no 16156930 and
16156395.  So to be absolutely certain, beyond any doubt, that you
have a pcm which will work with both transmissions, get the #16197427
part.

> That was my next question.   After comparing pinouts on the 4L80E equipped
> computer vs my 4L60E equppied computer,  the 4L80E has perhaps 2 wires
> different, and the addition of 2 more, where my harness has "empty" spots
> on the connector.  So, are the computers really different, or do they just
> not hook up the wires that would go to it?   I know the calpak would be
> different, 

Can you use the 2 "extra" wires to connect the "extra" trans speed
sensor?

>and perhaps that's the only difference?!?   Would they really
> make different computers for such a slight change and not enable/disable
> via sw?

Sometimes GM does things we mere mortals find stupefying.  Doesn't
look that way this time, though.

> 
> >>The 4L80E uses a different flywheel and torque converter. I'm not sure
> 
> >>whether the crankshaft end would need to be reworked to mate to the 4L80E.
> 
> The 4L80E would require a different torque converter from my 4L60E, but
> that's not a problem, as I don't use the stock converter anyway and would
> buy a higher stall after market unit.

Is there one available?  This trans originally comes with a twin
stator converter, plus TCC.  The THM400 converter is not a direct
replacement for this transmission.

> The flexplate is engine dependent
> and not tranny dependent.   I'm not running the one piece real seal
> crank/block anyway, but a gorgeous Cola Crank with a 4 bolt splayed cap block.
> 

Well, there are 3 additional converter mounting bolts.  If you are
comfortable leaving them out, or have enough material on your flywheel
to drill 3 more holes, you're set.  Of course an aftermarket converter
may not use all six.

> >>The transmissions are different lengths which would necessitate a change of
> >>your drive shaft.
> >
> >And probably rear mounting bracket, too.
> 
> The hardware to mount the tranny is of little concern as I consider that
> the easy part.   I'm just worried about the computer crap.   Mainly because
> I've gone thru about 150 eprom burns to get my engine dialed in to my liking.
> 
Even if the calibration would operate both transmissions, I'd bet
you'd be burning more Eproms.  In addition to the added inertia of the
larger trans, the gear ratios are not the same.  

	4L60E		4L80E
1st	3.06		2.42
2nd	1.63		1.42
3rd	1.00		1.00
4th	 .70		 .75
rev	2.08		2.29


> >I'm sure a swap is a good idea. I'd contact JET and see what they have for
> >kits--they sell a complete kit, TCM, 4L80E, harness, etc. Might be just the
> >trick to get you going.
> 
> I'm not sure how I could fool my stock computer into thinking there's no
> tranny hooked up if I were to use an aftermarket kit.

This would be a step backwars IMHO, but could be done by using an ECM
from a 1986-92 pickup with auto trans.  Then you're back to the chip
burning issue.

> 
> If I have to buy a new computer, I'd assume I'd want one for a '95 with a
> 350 and a 4L80e.  

See above.
>
> Some people have asked my for my BJYM code, and I'd be more than happy to
> share it.  I can also post my current code that I'm running with my engine
> setup.  
Yes, please do.  I have a base calibration for a 350/4L80E trans that
I will trade/post.  It will take me a few days, maybe couple of weeks,
to get it up there.  I have to pick up the PCM and build an adapter
for my burner.  

> Finding the original BJYM code will be a task, but I can upload my current
> config asap -- just tell me where.
ftp://efi332.eng.ohio-state.edu/incoming/

>  Also, not sure if I should post the
> MasterTune sw or not?  (good/bad?) 

Not a good idea to post copyrighted software here.  Been bad
experiences in the past.

> 
> 
> Thanks for all your help,
Not a problem.  With two calibrations, 4L60E and 4L80E, we may be able
to find some easy answers.
Shannen
> 
> Doug Bazarnic
>