If the transmission is healthy and any/all adjustments are done properly there should be no slippage.
No
my 1990 mercury marquis transmission is slipping in overdrive what do i need to look for and how can i fix it
The transmission needs repair. The electronic control system causes the transmission to stay in 2nd gear when it detects a problem, such as slipping in 3rd gear or overdrive. This allows the car to be driven in an emergency.
The gearing may be bad, the tranny may be slipping, or the fluid and filter may simply need to be replaced. A bad filter and low or bad fluid can cause slipping or lack of shifting.
what would transmission not to shift in to overdrive
If you accelerate and the transmission shifts to a lower gear of the overdrive disengages the RPMs will increase. If the vehicle has a manual transmission a slipping clutch will cause the RPMs to increase if the clutch is defective.
The Bands in the transmission are slipping/ the tranny is bad.
if their is no slipping or any other transmission issues and it is just only the loss of overdrive try replacing the brake light switch
the overdrive sencer
yes and it may cause damage to the transmission if filled too much.
No. A slipping transmission is caused by a low fluid level, or failure of friction parts inside the transmission. Though a failing Vehicle Speed Sensor(VSS) can cause symptoms that can make it appear that the transmission is slipping, even though it is not.
My 1984 corvette transmission is not shifting into overdrive. It shifts first thru third fine.
If it is slipping in those gears then it is time for a rebuild. no EASY FIX