I own a 1992 Cadillac Seville STS with a 4.9L(300) V8 witha 4T60E.
I've owned it for a week and had no problems. Then the transmission slipped when I was going through a light when I got on it. It then caught felt like it tried twisting the front of the car. I thought ok be easy it on it. It shifted just fine. Drove for another 25 minutes and it started not wanting to shift. It got stuck in 1st gear a couple times. Got it home and it seemed like it was a quart low, but it makes a "supercharger" whine when trying to accellerate and comes from right in front of me. Sound like where the TCC is at. (I know it's not the PS or any other belt accessories.) Now, it's not wanting to shift out of first gear. I can it is at 3,000 RPMs and shifts hard, but it goes into second gear because I can get it to go into the other 2 gears just fine after that. Is it the cooler is clogged, TCC soleniod, or something else?

I know it hasn't lost a gear, because my truck lost a gear and it would skip that gear. This car doesn't do that. It usually just stays in first. Also no SES and no codes stored on the PCM.

 

I took the Caddy to the dealership they say it needs a rebuild, but if I rev it up high enough I can get it to shift into the other gears. They want $3,000 to rebuild the transmission. I just paid $1,000 for the car a week earlier. The transmission only has 129,000 miles and shift smooth and fine all week till that happened.

 

Update, I'm trying to change out tcc solenoid, the 3 shift solenoids, and the vac*** modulator. Hoping those will fix the problem. I'm trying to take off this mounting bracket. I can't get it out, it keeps hitting the brake lines when I try pulling it out. I'm tempted to cut the top of the bracket. Do you think the 2 sides of the bracket will still hold the tranny/motor in place without the top bar or is there a better way to remove it?

 

Solenoids should set codes, trash in governor could cause condition. What is/ was fluid's condition when you got car? Bright red - condition may be why it's your car now. Don't cut up brackets to make it easier to do, it might bite you later.Beleive me GM spent alot of money designing these things, and if they thought they could save $0.10 it would not be there. Just do it right.

 

The fluid was about as red as it would be if it came out of a new bottle. The filter looked old and dirty. I also notice the rubber hose, connected to the vac*** modulator, was in bad shape. I'm still going to at least look into the side pan to check the solenoids.

 

I have feeling previous owner had transmission fluid flushed,hoping to correct trans problem. Thats why new fluid old filter. You may insufficient vacuum to modulator due to carbon build up in throttle body ports. Would cause 4th gear to go. The lack of vacuum signal can cause lack of line pressure causing other clutches to slip.Leading to time for new trans.and previous owner decided time for new car instead.

 

I got tired of trying to get the side pan off. Noticed that I had no choice, but to drop the suspension and take the half shaft out too. So I gave up. Put it back together with new fluid, filter, and vac*** modulator. Now, VATS is messing up for me. Transmission wise, starts in first get up to 3,500 to 4,500 RPMs and let off it goes in to second almost like it didn't even shift. I couldn't even feel it, but it was in second then goes into third. Then it won't go into fourth because I'm going 2,000 RPMs doing 55 MPH. It has to be the soleniod that controls 1st and 4th. I'm going to find someone else to change it for me. Also the fuse is not blown for the transmission, unless there is another one beside under the hood.

 

When the transmission warms up, it shifts fine. Fluid was a little low, but is fine now. It does get into 4th gear, but when it's in 4th gear, the car rans at 2000 RPMs at 55 MPH. Should the RPMs be lower? I have a check engine light on, but is for the back O2 sensor since the wire is broke.