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TCC 2nd gear question


Chevsica

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I have a 1994 Olds CS with the 3100. When it shifts into 2nd the tcc locks up within a half second, which is very harsh. Shifts from 2nd to 3rd and 3rd to 4th are not as harsh but the tcc seems to lock up instantly. When coming to a stop it will lug the engine in 3rd then down shift to 2nd and then lug it until it almost dies, around 300-400 rpm and then harshly shift into 1st. Once in first the tcc doesnt lock up. The tcc will not unlock when pressing the brake pedal either. I have cut the tan and black wires, position C and D on the transaxle plug, and nothing changes, still drives the same. I then cut the red wire and the car dies as soon as i put it in drive, as it should.

 

It also does not matter if the engine is hot or cold, it acts exactly the same either way.

 

Why does the tcc still lock up with the tan and black wires cut or do I have a different problem???

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Pretty sure the TCC shouldn't be locking at all in 1st...have you checked the modulator? A bad or disconnected modulator will cause very harsh shifts...and more often than not a pretty decent vacuum leak.

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Pretty sure the TCC shouldn't be locking at all in 1st...have you checked the modulator? A bad or disconnected modulator will cause very harsh shifts...and more often than not a pretty decent vacuum leak.

 

the way the valvebody is setup, it's actually impossible for the TCC to be engaged in 1st, according to GM.

 

also, 94 CS 4T60E connector:

 

A = shift solenoid A (light green)

B = shift solenoid B (yellow w/black stripe)

C = TCC PWM (brown)

D = TCC (tan w/black stripe)

E = +12V for solenoids (brown)

F = trans temp signal (yellow)

G = trans temp ground (black)

 

a red wire was cut? there shouldn't be a red wire present. if you cut the +12V circuit, then that would shift the transmission into 3rd with the shifter in OD/D or 2nd with the shifter in 1/2.

 

if you did cut the C and D circuits, then the TCC isn't getting commanded on. it's possible that the valve/solenoid is stuck, but i haven't seen that with a 4T60E.

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The red wire I am talking about is the wire in the E position. I didn't look at the color just the letters on the plug, this is where I got that it was red. http://www.w-body.com/showthread.php/32929-ARGH!!-4th-Gear-is-gone-again-New-Symptoms-(sp-)/page2

 

The tcc is NOT locking up in first, only about a half a second after shifting into 2nd.

 

After cutting the wire in the E position and then placing the car into drive it immediately dies.

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Pic of connector I am talking about with the "e" wire temped back together. Could the modulator below the connector cause the transmission to stay in second gear too long, until around 300-400rpm, before downshifting into 1st?

I know it is dirty, just bought it and havent had a chance to clean it up!

7212FF93-6823-4E2B-AA29-9B1F57CC95C8-2026-000001B9DA06379F_zps82b5a59a.jpg[/img]

Edited by Chevsica
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A couple days ago I tried to post some videos of what it is doing. I guess the mods have to approve them. I understand why they have to be approved, but why does it take so long. I really need to get this car fixed.....

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vids were helpful.

 

the torque converter or something in the valvebody is doing it. probably valvebody if i had to internet-diagnose.

 

the TCC valve seems like it's stuck in the "on" position. when in 1st, this fluid passage is bypassed so the TCC can never get locked in 1st gear, but as soon as you drop into 2nd, the torque converter does seem to be locked. since you clipped the wires, the ECM is in no way commanding it, so the TCC should stay unlocked at all times. clipping the PWM wire causes the line pressure that gets sent to the TCC valve to be at full pressure. when you did the temporary cut of the +12V feed to the entire transaxle, when you shifted out of park/neutral, you actually shifted into 3rd. since you were shifted into 3rd without vehicle movement and the TCC being stuck on, stall occurs.

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vids were helpful.

 

the torque converter or something in the valvebody is doing it. probably valvebody if i had to internet-diagnose.

 

the TCC valve seems like it's stuck in the "on" position. when in 1st, this fluid passage is bypassed so the TCC can never get locked in 1st gear, but as soon as you drop into 2nd, the torque converter does seem to be locked. since you clipped the wires, the ECM is in no way commanding it, so the TCC should stay unlocked at all times. clipping the PWM wire causes the line pressure that gets sent to the TCC valve to be at full pressure. when you did the temporary cut of the +12V feed to the entire transaxle, when you shifted out of park/neutral, you actually shifted into 3rd. since you were shifted into 3rd without vehicle movement and the TCC being stuck on, stall occurs.

 

So that would rule out the modulator? It looks like it is sucking a little transmission fluid through the vacuum line.

 

How would I go about getting the tcc solenoid unstuck?

 

edit* I sure am glad that the tcc is bypassed in this car. That sure sucked in the 89 Grand Am I had about ten years ago!!!

Edited by Chevsica
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i wouldn't think it would be the modulator... but if it's leaking, it needs replaced, otherwise you're going to get weird line pressures.

 

unsticking the TCC valve? digging into the valve body.... at that point, it might be easier to get a junkyard transmission with a warranty.

 

89GA with an auto would probably by a 3T40(TH125C)... those had similar TCC valve issues, though they were much more common.

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