Adjustable Transmission Modulators - Page 4 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

General GM Chat When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made. Chat about all things GM (and related cars). Off-topic stuff should be in the Lounge, and all Model specific mechanical problems should be posted in the proper forum.

Thread Tools Search this Thread
Old 04-26-2012, 08:37 PM   #31
Posts like a V-Tak
LeSabre L27's Avatar
Join Date: Apr 2012
Location: SW PA
Posts: 44
Thanks: 0
Thanked 0 Times in 0 Posts
LeSabre L27 is on a distinguished road

Yet more good info above, thank you..
Not to sound stupid, but if I elect to experiment with a TCC toggle switch,
where do I locate the PCM'* command wire to the TCC..?
Where is it & what color(*) is it..?

Also, I know that on some transmissions, manual shifting can actually harm them.
Will manually up and/or down shifting the transaxles in our cars cause damage..?
Not just between 3rd and 4th (OD) as discussed above,
but also manually downshifting into 2nd for engine-braking on grades,
then upshifting back into 3rd and/or 4th..?
Is that harmful..?
I do not drive around constantly manually shifting the transaxle,
but I do hit some pretty long & steep grades on a daily basis,
and like to utilize engine-braking to help control speed on downgrades.
If it'* harmful in any way I won't do it - Brakes are cheaper to replace than a transaxle..
LeSabre L27 is offline   Reply With Quote
Old 04-26-2012, 09:18 PM   #32
Senior Member
Posts like a Northstar
RobertISaar's Avatar
Join Date: Jul 2010
Location: Camden, MI
Posts: 615
Thanks: 0
Thanked 0 Times in 0 Posts
RobertISaar is on a distinguished road

there are two TCC related circuits on the transaxle connector, one for TCC PWM, the other is just TCC. you'll want to "intercept" TCC. it should be a tan wire, black stripe, in position "D". if that circuit is open, the TCC will never apply. if closed, will only apply the TCC when the PCM wants it applied.

manually shifting between 3 and 4(or D/3 or D/OD depending on how your shifter is labeled) is no problem at pretty much any speed. manually dropping into 2nd is.... rough, to say the least, and i really wouldn't recommend it unless necessary. it may or may not be damaging to the transaxle, but it is definitely damaging to trans/engine mounts.

for maximum engine braking, i have my tune setup so that when i lift my foot off of the throttle, the TCC won't automatically unlock until it gets down to the MPH threshold to unlock in a 0% TPS situation, which is around 36MPH in 4th and 26 MPH in 3rd. TCC staying locked alone helps a little, but i also have DFCO allowed to happen in the same instance, combined they produce quite an effect.

also, interesting tidbit: 1st gear is the only gear the PCM can actually force in/out... due to the way the manual shaft is setup on the 4T60E, if the PCM is commanding 4th and the shifter is in 1st or 2nd, the highest gear it will actually achieve is 2nd. shifter in 3rd, highest achievable gear is 3rd.

anyways, that last part is just trivia really, but useful in certain situations, like if the trans loses all power to the shift solenoids for some reason, moving the shifter between 2 and 3 will get you 2 forward gears instead of just 3(3rd because when both solenoids are de-energized, 3rd gear is being selected).
RobertISaar is offline   Reply With Quote
Old 05-08-2012, 06:51 PM   #33
Junior Member
Join Date: May 2012
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
JedRule is on a distinguished road

I am new to this forum and also new to NE PA. I had a banging shift both upshift and downshift on the hills here.(there weren't any hills on Long Island where I used to live). A local shop found trans fluid in the modulator and replaced it with one of the adjustible ones. He also installed a vacume restrictor in the line. I have removed the restrictor and adjusted the modulator screw to 2 turns out but I still get harsh shifts above 40 mph. Should I get an original GM modulator @ $155? The trans was rebuilt 2 years ago for an intermittant loss of TCC after one hour driving at highway speed.
JedRule is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
adjustable transmission shift modulator SLOWBONNI Performance, Brainstorming & Tuning 5 02-08-2007 12:07 AM
adjustable transmission modulator question c0rsa180 Performance, Brainstorming & Tuning 4 05-06-2006 03:02 PM
FM modulators J Wikoff Audio (and aftermarket electronics) 6 01-15-2006 04:45 PM
Adjustable headrests??? OLBlueEyesBonne 1992-1999 3 07-18-2003 12:41 AM
Front Strut Part Numbers w/ Adjustable Suspension CDecker 1992-1999 1 03-07-2003 08:22 PM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -4. The time now is 02:29 PM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.