4T60 - ACC solenoid replacement (Page 1/1)
Cajun FEB 23, 07:22 AM
It's looking more and more like I will need to replace the TTC solenoid in my 4T60. I have one more test cycle to confirm the TTC solenoid is the issue before I begin opening up the transmission.

My question to the group with 4T60s, who has replaced the solenoid before and can it be done without dropping the cradle?

Thanks in advance for your feedback.

[This message has been edited by Cajun (edited 02-23-2019).]

theogre FEB 23, 10:00 AM
Is under left cover? Should be able w/o dropping cradle same as th125c IF you still have room to remove the cover. Don't have dimensions to tell.
Might be able to remove back cradle bolts and/or trans mount parts to get a little more room but watch wiring exhaust etc or can pull joints/connectors and wreck them.

"Failed" solenoid usually results in stalled engine trying to stop after running a bit on highway w/ TCC locked.
Doesn't have to be on freeway turnpike etc limited access roads. Any road that allows TCC locking can make solenoid to heat up and that heat closes gap and makes core binding.
Some times changing fluid can help If problem is dirt in the solenoid but you need more then dropping the pan to drop ~3 quarts...
Can try my method in See my Cave, Automatic but don't know which tube is outlet so should have both sides of any joint doing to drain pan.

Problem is If fluid helps may not help right away. Can take some time for new fluid to clean the solenoid.
Can be a "waste of time" but changing fluid w/ new Dextron III or VI is easier then replacing the solenoid.

I say usually above because 4T60 w/ ECM used in most Fiero have iffy wiring to make TCC locking. Can be that iffy wiring causing problems. Example: Many have no 3rd or 4th gear pressure switches wired and Fiero ECM can try to lock the TC at weird times.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Cajun MAR 07, 07:42 PM
After numerous electrical checks and tests I have verified the TCC solenoid is functional. So, it does not look like I will be opening the side cover of the transmission.

Now on to the next issue, not shifting into 4th gear. It may simply be a matter of adjusting the TV cable? Fingers crossed...
Cajun APR 23, 02:09 PM
Happy days are here once again!! After about 10 or 12 adjustments of the TV cable over several weeks I finally got it set to where I now have 4th gear operational.

Doing once again doing hiway speeds (70) at 2100 rpm.
theogre APR 23, 06:41 PM
4T60 also has a Vacuum Modulator and a Governor to control shifting too.
Late or no upshift can be the governor w/ wrong weights for the car or just dirt plugging it up.
VM must get Intake Manifold vacuum not port vacuum from TB/TBI.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Cajun APR 26, 08:09 AM
Appreciate the feedback "theorge" , but in my case it was all about the TV cable adjustment. I had already ruled out the VM, linkage, etc.