[Gmecm] Now 4L80E Questions.

[davesnothereman at netscape.net]

Hi, Don.

GM literature specifies some of the changes in solenoids.

1) Internally, solenoids vary greatly
    a) Size of spool valve has been increased
    b)spring was added to eliminate need for 10 second cleaning pulse
2) "balance" oil removed from end of solenoid
3) New solenoid resistance is slightly higher, 3-8 Ohms
     a) average duty cycle readings will be slightly higher due to 
greater resistance

4) Older design Bosch part, silver in color, cannot replace newer 
Holley unit, Black in color.

My recollection is, and service bulletins seem to support, that one 
reason for the change in frequency was to eliminate unwanted RFI.  The 
older vehicles would "hum" if certain AM frequencies were tuned in.

There is a note in GM service bulletin # 477118 regarding changeover 
model transmissions.
"1994 4L80-E/4L80-EHD Goodwrench transmissions cannot be used to 
service any 1993 or prior applications."
However a service bulletin detailing mixing and matching 1st and 2nd 
design trans parts (bulletin no 266) indicates that any failed pressure 
control solenoid should be replaced with the second design solenoid, 
part no 8677314.

Some questions:
If you go to www.gmpartsdirect.com and look up the solenoid part 
numbers for pre 94 trans and for 94+ models, does GM indicate the new 
solenoid should be retrofitted into the old trans?

Is there a 94 PCM with the same part number and application as your 
pre-94 PCM, allowing the older calibration to be replaced with a newer 
one?  Positive answers to these question can help ease your mind.

Zaphod

-----Original Message-----
From: Don Sauman <donsauman at cythera.net>
To: gmecm at diy-efi.org
Sent: Mon, 06 Mar 2006 12:01:49 +0800
Subject: [Gmecm] Was: Geting rid of electronic transmission.

  I have been following all of this with some interest.

  In the spirit of efi and I guess PCMs, I will probably need to 
reprogram an OBD-I PCM (Don't really want to deal with OBD-II if I can 
avoid it) to deal with the changed force motor in the 4L80-E autotrans. 
Previously it operated at 292.5 Hz level but in 1994 was changed to 614 
Hz level.

 I have a 1996 trans, and a pre-1994 PCM is being sent to me.

  Can someone who is knowledgeable explain how the force motor works 
(perhaps it is solenoid PWM?) and how the PCM may need to be altered to 
suit the upgraded force motor. Going back to an earlier force motor is 
not an option is not an option as the torque signal feed passage is no 
longer drilled.

  Also, according to the ATSG Manual, with the new design force motor, 
the need for the cleaning cycle is eliminated, so the force motor is no 
longer pulsed every 10 seconds by the PCM/TCM.

  The new force motor (8684216) is applicable to 1994- up 4L80-E, 
4L60-E, and 4T80-E transmissions.

 Cheers
 Don

 -- Don Sauman
 35 Asteroid Way
 Carlisle 6101
 Western Australia

 P: 08 9361 0337
 F: 08 9361 0581
 M: 0427 389 547 CDMA
 M: 0413 746 695 GSM


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