94 grand prix won't shift into over drive
Sorry, but there is nothing that I can tell you to do to magically fix it. You'll have to have a local mechanic diagnose your issue. It very well might be the transmission is worn out. Good Luck!
Are you sure that this a problem with shifting into 4th, or is it the torque converter which is not locking up? The two can be confused with each other, seeing as they appear to give a similar result. This would be a 4T60E trans, it should shift into 4th before the lock up takes place, the only time this would differ if you have the trans selector lever in third, then the converter will *lock up* without waiting for 4th to happen. You need to have the trans scanned, see if there are any codes present, this will require visiting a trans shop.
These transmissions are notorious for this type of failure. Will cost about $1500.00 to fix. My 2000 GT Coupe with 153,000 miles on it has also lost 4th (OD) and torque converter lock-up. I just drive it with the transmission in "3" instead of "D". Cuts into gas mileage but otherwise it runs fine that way. It's my "toy" so I don't drive it that often for gas mileage to matter. HTH. -Jim
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