Transmission Problems; 94 Skylark, 3.1L, 4T60-E

[JRCates]

Background: My parents have a 94 Buick Skylark with a 3.1L eng and a 4T60-E trans, the car has 235K miles on it.

Problem: It will drive fine for a little ways then it is like it goes into neutral, and it doesn't matter which gear it is in, or which one you move it to (R, OD, 3, 2) but I can turn the engine off and wait 15-20 seconds and then restart it and it will drive fine for a little ways and then it quits again.
I tried unplugging the electrical connector, but that didn't change any thing. When it first starts the Transmission makes a rattling noise but as it warms up that quites down. For the last several weeks it has been shifting kinda rough, so a couple of weeks ago I changed the fluid/filter and didn't have any problems until now. [/b]

[TheProfessor]

whens the last time the tranny fluid and filter have been changed

[JRCates]

I changed the fluid and filter about 2-3 weeks ago, the pan and every thing looked clean.

[dennyJ]

tech bulliten

If you look under this site's tech bullitens for the 4t60-e trans, you'll see one titled "loss of drive and erractic shifts". I'd bet you'll find and answer there.

[Quinky]

I'd check fluid level first.. make sure it's topped up.. If fluid level is ok, then I'd say the torque converter has packed it in.. and you are going to have to have the transmission taken out and looked at..

[gpse3400]

A harsh shift is probably due to the Vacuum Modulator going bad. that would also cause the trans to make noise when its cold. As far as the erratic shifting I'm not sure. The modulator you can obtain at a AutoZone or Advance Auto. They are smaller than the original and they are adjutable. Tayor your shift feel from soft to hard. You'll know if your modulator is shot if: remove the modulator(can like thing ont he front of the trans with te metal vacuum line going to it), hold the moudlator upside down and see if trans fluid comes out of the vacuum fitting. if so, the modulator is bad.

[Cool_The_Slain]

What kind of rattling noise is it? I have a rattling noise when I am at low rpms (2000-3500), but it only does it in gear. Also when I use the second gear start it doesn't rattle. Haven't had any other problems with the tranny though. Was it rattling before you had other problems? I guess I just want to know if this is a sign of impending doom.

P.S. Sorry to interrupt this thread; it just made me remember about my noise.

[Quinky]

Problem: It will drive fine for a little ways then it is like it goes into neutral, and it doesn't matter which gear it is in, or which one you move it to (R, OD, 3, 2) but I can turn the engine off and wait 15-20 seconds and then restart it and it will drive fine for a little ways and then it quits again.

How can a bad shift mod do that?

[JRCates]

I have checked the TSB " titled 'loss of drive and erractic shifts'" it referes to a short in the wiring between the PCM and the Transmission, I have unplugged the electrical connector (you can manualy shift it between the 2nd and 3rd gear ranges) and driven it and it has still slipped or gone into "Neutral" or whatever you want to call it.

[JRCates]

Quinky sugested the Torque Converter, is that likely enough problem, to justify pulling the trans and replaceing the +/-$120 torque converter (I won't hold anybody liable for there appianon)?

[Quinky]

You wont want to replace just the torque converter.. that is just 1 of the things that could have gone.. it's possible you could have broken something else inside the trasnmission.. either way you look at it.. the transmission has to come out.. a used one put in.. or yours rebuilt.. If you have check fluid level and it is still where it's suposed to be... then I'd say better start pricing out a rebuild.. because only low fluid level or something internal in the transmission will cause a neutrul problem..

[dennyJ]

you said,
"I have checked the TSB " titled 'loss of drive and erractic shifts'" it referes to a short in the wiring between the PCM and the Transmission,"

The TSB, in the same sentence also says,
"or an internal electrical condition in the transaxle."

I'm not an expert and have no experience with this problem but perhaps 12volts is applied to the trans and the PCM completes the circuit to ground to activate the solenoids. Even if you disconnect the connection to the PCM, if there is an internal intermitant short to ground, it could still cause solenoids to activate when they are not supposed to.
I'd pull the pan and check the internal wiring. There may be a wire with insulation worn through from rubbing on another surface causing an intermittant short to ground.
You could also, disconnect the connector to the PCM and one by one, connect a volt meter to each terminal. Note the voltmeterreading, when the trans is normal, then see if there is a change when the trans "goes to neutral", that would be where the trouble is located.
I.E. if a terminal has voltage when trans is OK and has none when the trans goes to neutral, that terminal is shorting to ground.
You should also note, does this happen only when the trans is warm(normal temperature)? My TCC used to stick only when the trans got warm. If these solenoids are a similar design, one may be sticking when warm.
good luck.

[Quinky]

Problem: It will drive fine for a little ways then it is like it goes into neutral, and it doesn't matter which gear it is in, or which one you move it to (R, OD, 3, 2) but I can turn the engine off and wait 15-20 seconds and then restart it and it will drive fine for a little ways and then it quits again.

This is not an erratic shifting problem and can not be cause by the soliniods, or an electrical problem with this transmission..