More stuff on swapping a 4L60e for a 4L80e

[Doug Bazarnic]

>> 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.

Ahh, I see.   My manual is for my '95 truck, so therefore, they wouldn't
mention the older part. :)


>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that part no is superceded by part no. 16197427.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16156930, superceded by part no 16197427.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.

Well I'll be dipped in sh*t!  :)  I replaced my ECM about two months ago
trying to track down an injector problem and the replacement part # that's
in my truck this very second is a 16197427!   Man you are good!   Where do
you find this info?   So, what is the proper calibration code for the 3/4
ton 5.7L w/4L80e & 3.73 rear gears?


>> 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?

Here are the differences that i see according to the pinout tables in my
service manual:

Pin		4l60e							4l80e
B10 	Cruise Signal					NOT USED      ** see note
E2  	3-2 cntrl solenoid				NOT USED
E10 	TCC solenoid cntrl				Idle speed actuator control (7.4 Liter only)
F2 	NOT USED						Input Speed High
F3 	NOT USED						Input Speed Low

Okay, here's some details:  the service manual lists, for these two
(actually 3, as one is diesel) computers, one is labeled 4.3L, 5.0L, 5.7L
(C/K) 4L60E and the other is listed as 4.3L, 5.7L 7.4L (C/K) 4L80E.    

** note:  In the table of pinouts of the PCM, the 4L80E table shows B10 as
not being used, however, the wiring diagram does indeed show it going to:
Cruise Control  Switch <- 396 Lt Blu / Blk

It looks like I could yank E2 and move it to F2, and move E10 to F3 and I
wont have to run any extra wires at all.

The connectors on the tranny are as follows:

Pin				4L60E								4L80E
A					1-2 Shift								1-2 Shift
B					2-3 Shift								2-3 Shift
C					Pressure Solen. High					Pressure Solen. High
D					Pressure Solen. Low					Pressure Solen. Low
E					Both Shift Slnd, TCC, and 3-2 high		+12 volt ( ign. crank on)
L					Fluid Temp High						Fluid Temp High
M					Fluid Temp Low						Fluid Temp Low
N					Range signal A						Range signal A
P					Range signal C						Range signal C
R					Range signal B						Range signal B
S					3-2 Cntrl Solenoid Low				TCC PWM Solenoid
T					TCC Solenoid (low)
U					TCC PWM Solenoid					


It looks like pin E is the same for both looking at the wiring diagram, as
it's the +12 side on all the solenoids in both cases.

It looks like U goes to S and the old S & T wires will become my Input
speed low & high wires.


>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.

Of course.   I'll check with Hughes transmissions and see what kind of
torque converters they have.  Generally Allison torque converters have the
6 lugs for mating to the flex plate.  


>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.

They usually don't use all 6 because they're cheap bastards :)


>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

Depending on what the 4L80e will cost me, I may purchase a lower gear set
for the tranny.    Then again, I don't know if it's really necessary, as I
can leave tracks from here to wazoo... :)   I have a video of me leaving
tracks over 85' long -- I can turn it into an .avi if you wanna see.

One other concern:  Where / how is the vehicle speed stored?   I have 3.73
rear gears and I don't know if they figure vehicle speed via the ECM or
gears in the tranny or what?

 Thanks for all your help,

>Not a problem.  With two calibrations, 4L60E and 4L80E, we may be able
>to find some easy answers.

If I knew the proper code, I'd be happy to go buy the calpak from the
dealer so you can see the differences.  For $30 or so, I could always use
the extra calpak :)

Doug Bazarnic