Auto trans question

[Tom H]

Hi,

I am working through the circuits&code that operate the auto trans pressure control solenoid. Could someone suggest a link that will give me an understanding of the auto trans?

I understand the mechanical bits / electrical bits.. the part I am missing is the why of things. There seems to be two separate circuits involved. One is a simple on/off and connects to one solenoid terminal. The other is a PWM that controls the current sent to the solenoid and connects to the other terminal. I guess this might be to reduce harsh shifts under light throttle (?)

Any help appreciated.

-Tom

[kur4o]

I don`t know much either but the pcm monitors the current to the solenoid. It measures the commanded and actual current that goes through it. The lower the current the higher the pressure.

The pcm constantly adjust the current so at light load the pressure is lower and bumped up at high load to the transmission.

I will try to get some description manual how the circuit works.

Here is some gm pcs info for now.

[JimCT_9C1]

There is good info in this thread to at least get you started.

http://www.gearhead-efi.com/Fuel-Inj...vations-(8051)

Hope this helps,

Jim

[Barry Lyndon]

I'm going through something similar on my 1993 4T60E after having had a transaxle rebuild by an incompetent shop.
When I finally picked the car up, after like two months of it being in his shop, he mentioned something about having problems with using the wrong trans wiring harness, and how it required a 1992 harness.
But I assumed at that time, like two years ago, that he actually resolved that problem.

However, ever since, the trans hasn't shifted right. It's like the torque converter is always on. Bogs down. Low gears slip...
Long story made shorter:

The PWM TCC solenoid is supposed to be grounded by the PCM to engage it, and it varies the fluid pressure on the TCC solenoid line (or something)... but, in my case, there is no 12V signal on that wire to be grounded -- which is the root of the problems I'm having. I think it's stuck fully engaged (or is it disengaged?).

TunerProRT is telling me that the TCC PWM duty cycle is 0% pretty much all of the time, except at highway speeds where it fluctuates. The factory service manual is telling me that 0% is full line pressure.

So what I think I'm going to have to do is pull the side cover off the transaxle and trace the wiring to the solenoids and look for shorts/opens.

[Tom H]

Thank you both.... great info!

-Tom

[Tom H]

Here is the schematic I have made for the trans pressure control solenoid. Please note the schematic is a "best effort" work and might contain some error

-TomCapture.jpg