Lumina 4T60E trans trouble

[bishop5307]

Recently got ahold of a trans job for a "friend". He wanted the solenoids changed in his 1996 Lumina because the TCC would stay locked on and sometimes the car would not come out of 1st gear. He had wired the TCC solenoid so they wouldn't come on and drove the car for a year.

I changed the solenoids and put the wiring back to production. When I tset drove the car in drive, it would hesitate during the 1-2 shift. It was actually skipping second. Manual second felt like the brakes were put on and the car would not accelerate but did not slip.

I pulled the trans and went through it, found nothing. Clutches and bands looked good, no metal, valves and servos moved. I put both sprags in and also new seals everywhere. I took out each valve out of the valve body and made sure they moved. Some had marks on them but still moved. I hit those with some 600 grit paper to clean off any burrs.

The next test drive, 2nd gear returned!! But 1st and 4th are gone. The A solenoid does not respond to scan tools output controls although it once set a P0756 for the B solenoid. The B solenoid works OK and the symptoms are more related to the A solenoid. Electrically, they ohm OK and are hooked up. The PCM is sending the grounds correctly to each solenoid so I am sure the problem is in the trans. I can set PCM codes related to each solenoid by disconnecting each wire via a jumper harness I made.

I am ripping out the valve body to see if the 1-2 valve for the A solenoid is stuck or if there is a problem in that area. If I don't find anything, it is getting a valve body.

That is, unless I find out otherwise from the wise people on this forum.
Any suggestions or anyone have a similiar scenario??

Randy

[jeffcoslacker]

Just to clarify...you changed both the shift solenoids AND the TCC solenoid in the side cover?

[bishop5307]

Originally Posted by jeffcoslacker

Just to clarify...you changed both the shift solenoids AND the TCC solenoid in the side cover?

All 4 solenoids, A, B, TCC, TCC PWM.

Tonight I went out to look at it. I went to pull it into the shop and it was in 1st! I took off my jumper harness and took it for a ride. All gears worked and properly! I drove around for a while and then it started to take off in second and then jump to first and act normally. The hotter it got, the longer it stayed in second before jumping into first then shifting normal. I cleaned grounds just to be sure they were OK.

Forward servo?? Filter?? A Solenoid??

Randy

[jeffcoslacker]

Eek.

This is beyond me. There isn't some re-initialization you have to do is there?

[jeffcoslacker]

Can you watch the VSS signal?

[maxwedge]

You need to get this on a bi-directional trans scanner and you can command shifts and confirm solenoid operation and slippage errors.

[bishop5307]

Originally Posted by maxwedge

You need to get this on a bi-directional trans scanner and you can command shifts and confirm solenoid operation and slippage errors.

Got both a Tech 1 and Tech2 as well as the Snap On one. I work for GM and the guys here can't figure it out either, too old for them.

I am trying to decide if the torque converter, forward servo or pump would cause something like this. Or trying to cross them off the list. When it is trying to start off in 2nd, if I brake torque it a bit and get the RPM's up (fluid pressure), it will jump into 1st.

Trying a few more things and will post results.

Randy