Automatic transmissions tend to have a narrow range of problems that affect them, as compared to engines which seem to have an endless list of things that can go wrong. That is, transmission problems tend to be limited to being unable to shift the selector into any gear, not being able to move it to certain gears, there being a delayed or jerky gear change, unusual noises heard during the gear changes, slippage where the engine revs increase without any increase in engine speed and finally, when the vehicle can move with it is park or neutral.
The inability to select gears is most likely a problem with the transmission fluid. Either there is not enough fluid in the system, or there is a problem with a faulty oil pump or an old and clogged up oil filter. A routine and proper service of the transmission fluid should resolve the problem, and this should be done no less than every thirty thousand miles; every twenty thousand miles is a better.
When there is a delayed reaction to the effect of selecting a gear, this can suggest problems with the computer controls, or the solenoids and the spring loaded dampeners called actuators controlled by the computers and this is more likely to require the services of a professional with specialist diagnostics equipment to get the bottom of the issue. If the vehicle suddenly and violently thumps into gear, then this is most likely the spring loaded actuators at the center of the problem.
Slippage is easy to detect because it is quite noticeable that when you push down the accelerator, you can hear the increase in engine revs, but there is no acceleration of the vehicle; no sense of increased power to the wheels. This may be a low fluid situation, and it is wise to check the transmission for its color. Good clean transmission should be a red tone, and if it is dark or blackened, then it has been polluted by the components being worn out. Dark colored fluid is most likely caused by the internal clutch mechanism or bans are out of adjustment, causing them to slip and to wear out rather than provide traction. This can quickly lead to very expensive repairs being needed if it is not caught early enough. Urgent servicing should be sought if this is detected, and no heavy towing should be down while the vehicle is in this condition. Slippage can quickly lead to a total burning out of the clutch and bans mechanisms all leading to the need for a replacement transmission.
Finally, difficulty with selecting low gears or reverse can most likely point to problems with the torque converter. It is a clutch that can only allow movement in one direction, and if it is not working properly, it most likely won’t allow low or reverse gear selection.
Of course, there is always the possibility that one of the gears themselves has been stripped.
