The transmission in my mother's 2000 deville has begun shifting very hard from 2nd to 3rd gear. The car still shows 100% transmission fluid life. No diagnostic trouble codes have been stored. Has anyone experienced this specific problem? If so, what is the culprit. I don't need any guesses because I can troubleshoot as good as anybody. I really do need a specific answer. I've read these cars have 2 shift solenoids. Could one of these be bad delaying the shifting enough to make it a hard shift? Right now we're going to change the fluid to see if that helps. I know it cant hurt. The car has probably 40,000 miles on it.

 

I was becoming concerned about the shifting of my 00 DHS not feeling quite right any more. Nothing too noticeable, but I could tell. My independent Caddy mechanic did a complete tranny flush and added a conditioner. Within an hour the tranny felt like new again. Don't get the plain jane fluid change where they just drop the pan; it leaves too much old oil in the system.

 

My '00 Deville keeps giving me a "check engine" for a torque converter slip. Also shifts hard once in a great while. Time for a tranny fluid change anyway. To do myself, how do you do a "complete" flush??? Hate bringing it to a mechanic. Any idea would be appreciated. Note to original post, local tranny guy checked it out when I first got the engine code. Said a lot of them do this because the sensors are very sensitive. Never had another issue for the last 50K.

 

My mechanic did the complete tranny flush. I think it may take some special equipment and is more expensive than a regular flush. It is supposed to remove most of the fluid in all the tranny parts including the torque converter. Basically, they suck the oil out and/or flush the whole system with fresh fluid until it's all fresh and clean. He also said it is wise to do it every few years, as if the filter gets clogged it's about a thousand bucks to change the filter due to its inaccessibility!

BTW, the tranny oil life indicator on my OO has never gotten below 99% life left. I asked a dealer, who said it does not get used up like engine oil. If the computer doesn't detect any severe usage such as extreme engine or tranny fluid overheating etc., theoretically the oil can last a lifetime. Hence, the percent tranny oil life left goes down very slowly, maybe not at all for a long time if there is no hard usage detected.

 

Thanks. Definitely have a local tranny shop that I trust do the flush. About to hit 100k so I expect to spend a few bucks on maintenance. Can you suggest anything else? I plan to flush the cooling system, tranny, change plugs, typical stuff.

Pete

 

YES! One more thing: The battery is located under the rear right seat area. Pull up the cushion. It comes up easily. Be sure that the battery is not leaking acid onto the floor pan. If it is, remove the battery and clean it up quick. I let mine go, the battery aged, leaked horribly, and literally ate a hole clear through my floor pan! That explained why I was starting to hear an exhaust sound intruding inside, even though outside it was unchanged. The pipes were right under the hole. It is a known problem on this Deville/DHS/DTS model and the Pontiac Bonneville of the same year. The car was out of warranty and the dealer wanted $500 to weld in a floor pan insert specifically made by GM to fix this problem. I flushed the acid out (through the hole!), sprayed the rusted metal with a rust remover, then a gray primer paint, then used silicone sealer to glue down a flat sheet of clear plexiglass or plastic to cover the hole, keep out dirt and water, and support the battery weight. Be sure if you remove the battery that you put the rubber vent tubes back in place (or replace if damaged). Otherwise, you'll get battery acid fumes inside. Check this NOW! Be sure when you replace the seat that any wiring harnesses to things like seat heaters and rear lumbar adjustments, if you have them, did not pull apart when you pulled up the seat. Otherwise, you'll have dead gadgets.

 

Thanks. Sounds like a good time to check that-6 years old, 100k miles. Have had the seat out before. easy enough to check.