Hi guys, I'm new to the forum but I have come here in the past while doing research for fixing my car.

I have a 2002 Monte Carlo 3800 SS that I bought as my first car six years ago. I've put about 20,000 mikes on it since (currently around 185,000 miles on it). Overall it has been pretty reliable apart from intake manifold gaskets and power steering problems.

Up until recently the car was running fine, it always had a small whine to it in the engine bay since I've bought it so I haven't thought much about it. However, yesterday on my way to work it sounded like the whine was worse than usual, or maybe it was a different noise entirely. The thing is, when in gear, the whine won't start until the transmission is trying to shift to second gear, but in park, you can hear it as soon as you rev the engine. Another noticeable thing was that the transmission started shifting sluggishly. I especially noticed at stop lights that the takeoffs were dramatically reduced in power, it seemed to stay stuck in first gear until the engine was revved pretty high, then it would slam into second. Usually on my takeoffs it always seemed to start out in second gear, or shift pretty quickly to it given how hard you hit the throttle from a stopped position. Another thing I have noticed now is that it will shift into overdrive for a minute or two when you get to cruising speed, but then you can hear and feel the transmission shutter and drop to a lower gear. It wouldn't shift back to overdrive until after coming to a full stop and speeding up again. In addition, I now have DTC P0753, so that seems to explain the 1-2 shifting problem, but not the high gear problem. Lastly, and this might be unrelated, but starting yesterday whenever I put the car in park it won't automatically unlock the doors, and I have to do it manually. It will automatically lock the doors when going from park to drive, however.

I don't know for certain if the previous owner ever changed the transmission fluid, but I know I never have. I'm also not to familiar with how these transmissions work (never needed to do research on them until now since it has been reliable), but from what I've read over the past day it seems like the 1-2 shift solenoid could be at fault, although that doesn't seem to explain the high gear problem.

If anybody has any suggestions or experiences with something like this, I would really appreciate it. If any more information is needed, don't hesitate to ask. Thanks in advance for the help.

 

Given the unknown service history, I'd do a fluid change + filter first. Id mostly be worried about the filter being plugged.

Beyond that, I'd get ready to make a tough decision - is it headed to the scrap yard or are you dragging the piggy bank out for a rebuild?

Seriously though, if you plan to keep the car, I'd probably take it to a transmission shop for an accurate diagnosis of the issues. Itll be easier to make the decision if you've got a list from an expert of the minimum it needs to fix. I will say though, its had a really long life if its original, so if it has to come out for any reason, it really needs a refresh across the board if you plan to keep it.

 

Last time my trans went, it sounded like a high pitched buzzing. Ended up being the torque converter rubbing on something.. Not sure exactly as I know nothing about transmissions.

 

Thanks for the replies, based on what you guys said and what I've been reading I think that a fluid and filter change is in order at the minimum. While doing so I can inspect the fluid and filter and see if there is an abnormal amount of metal/clutch material present. I will probably take it to a transmission place as well to see what they think about it.