Bad clutch? Bad transmission? Worn synchronizer?
The signs of a bad transmission in a Mazda might include hard shifting or a refusal to shift into certain gears. A revving of the motor during the shift can also be a sign of a bad transmission.
Parking brake not released, bad torque converter, bad transmission shift solenoid or bad transmission in general, broken shift cable not engaging the transmission.
A bad transmission gear can cause your 1999 Nissan frontier to shift hard. Low transmission fluid can also cause the transmission to shift hard.
Could be low fluid,a bad sensor or transmission going bad.
A bad transmission.
In most modern cars, transmission shift is controlled by the computer. If the transmission won't shift, you most probably have a bad shift solenoid or solenoid circuit problem. You could also have a bad gear selector switch. Following that, check the computer and its related sensors. See the manufacturer's documentation for specifics.
The cable between the shift lever and the transmission may be bad.
You can detect a bad transmission using a diagnostic computer provided by the car's manufacturer or the car dealer. You can also detect this problem when the car fails to shift correctly or does not shift into a gear at all.
You may have a broken spring which disengages the transmission allowing it to shift or it is bad linkage going to the transmission.
the shift siliniod for AOD transmission is bad. it cost about 30 bucks and is usually special order
A bad sensor can cause the vehicle to shift at the wrong time or not at all.