1998 Cadillac Deville transmission

Tiny
LYNN HENDRIX
  • MEMBER
  • 1998 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 113,000 MILES
Just got the car. Person I got the from said it was not shifting good and was giving a code. He had the code check at a parts store and they said it was the shift solenoids. So I was going to replace them myself so I drop the pan and it was clean no metal in the pan. But then found out you have got to drop the valve body and take it apart to get to the clips that hold them in. So I took it to a shop and had the 1-2 and 2-3 solenoids replaced at a cost of 200.00 they said that the solenoids did not fix it. They said 2ed gear was not working only 1st -3ed
and overdrive and it needed to be overhauled at a cost of 2.000.00 dollars. I drove the car home from the shop only one mile and it would not shift out of 1st gear. So when I got home I took the cable lose from the battery and reset the computer. It then seem to be shifting ok. But I cant tell if it has a 2ed gear or not. It seems like it shifts a little harder from 2ed to 3ed then any other gear but I not sure if it just shifting from 1st to 3ed and there really is not a 2ed gear or not. But even with all that it will drive great for few miles and after I get up to about 45 miles hour then come to a stop the engine light comes on and when I go to take off it will not shift out of 1st gear. So I reset the computer and then it will shift fine. Could this be the converter solenoid bad? Or the over drive clutch slipping a little? I have not done the brake test yet to see if the converter is locking out by watching to see if the R.P.M.S jump up when I tap the brake to see if the converter is locking out like it should be.
Or to just drive it in 3ed gear at 45 to test and see if the engine light still comes on when not in overdrive. But I will test these two things tomorrow. But do you know of any other things that may be wrong that I should check? And how can I tell if there is not a 2ed gear? Not sure I believe this shop. And way is it not shifting out of first after the engine light comes on until I reset the computer? Is this some can of safety feature? From what I have read outside of the two shift solenoids I have already replaced there is a solenoid for the converter there is a pressure shift solenoid and a speed solenoid all are hard to get to. And cost a lot in labor to have replaced. I have read this 4t80-e transmission is a really good strong transmission that GM used for 10 years in many cars but these solenoids going bad is a real problem on them at around 100.000 miles. And there is so many of them. And all of them are hard to get to and replace. So it cost a lot to get them replaced. I only paid 1000.00 dollars for the car the blue book is only 1500.00 dollars so I cant see spending 2000.00 dollars to get the transmission overhauled even thou I really do like the car. Not sure if to flip the car and let someone else worrier with it or not. I have been out of work for 6 months now and don't have 2000.00 dollars to rebuild.
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Wednesday, May 13th, 2015 AT 4:25 PM

3 Replies

Tiny
HMAC300
  • EXPERT
The trans shop is correct it's probably a clutch pak that is bad and causing the problem. Not the converter.
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Thursday, May 14th, 2015 AT 7:54 AM
Tiny
LYNN HENDRIX
  • MEMBER
Tried a few test I read about on line last night.
Results were
first tried shifting in to 3ed and driving in 3ed gear after I reached 45 miles
per hour. Drove around for a while and engine light never came on.
Then tested the overdrive clutch by driving down the road in drive at 50
miles an hour and taping the brake to see if the R.P.M.S. Would jump up.
Did this many times and it was the same every time. When taping the brake
the R.P.M.S would jump up about 150 -200 R.P.M.S and then after a few seconds clutch would kick back in and R.P.M.S would drop back down.
This tells me the over drive clutch on the converter is working and locking in like it should. Drove around about a hour and engine light never came back on. And When engine light is not on it shifts fine. So With this information what do you think is wrong? And way when the engine light dose come on it will not shift out of 1st until I reset the computer?
Thanks
Lynn Hendrix.
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Thursday, May 14th, 2015 AT 8:56 AM
Tiny
HMAC300
  • EXPERT
If you are getting a code this is intermittent then check he wiring harness or maybe something else like a tcm. It can also be a connection. If yo say it's fine then I have say it's an electrical problem.
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Thursday, May 14th, 2015 AT 9:49 AM

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