How to Fix When Automatic Transmission Won’t Shift into 3rd Gear

A transmission is a complex piece of machinery the runs of lots of complicated mechanisms. Upkeep and maintenance of these machines are tricky since the glitch with a tiny component can mess up with the gearbox. Such a problem is automatic transmission won’t shift into 3rd gear.

The Signs of Automatic Transmission Won’t Shift into 3rd Gear

The problem could occur in a couple of forms such as:

  • The transmission shifts into the first and then to second gear but does not move into the third gear. It seems that the gear slips into neutral when you push it to the third.
  • Another instance could be the automatic transmission won’t shift into 3rd gear at all. It smoothly glides between the first and second and vice versa, but it just stays in second when you try to push it to the third. In that case, the catalytic converter can touch the side of the valve body area, overheating the transmission and creating metal shavings in the pan.
automatic transmission
Take immediate action when facing problems with shifting gears. Source: DriveSpark

Things to Do When Automatic Transmission Won’t Shift into 3rd Gear

Functional auto gearbox will shift up, down, and rest upon appropriate commands. But, when it fails to do so, there must be an internal hitch affecting the performance. If you ignore the signs for too long, it could lead to a possible failure of the transmission.

Let’s see what could be the reasons for the auto gearbox not to shift from second gear to the third.

Low Level of Fluid

Overheating could be a reason for the gear to stick and the low fluid level is the culprit for making the transmission overheated. Actually, low fluid levels are the source of several transmission-related issues. So, your first response to the gear-sticking problem should be to check the transmission oil.

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If the level is low, check for a leak in the input and output shaft seal, fluid lines, pan gasket, and the cooler. If there is no leak, flush out the old oil and refill the container. Also, don’t forget to look into the radiator for checking the coolant fluid. Sometimes, the cooler inside the radiator can leak and spoil the radiator coolant.

Check the Throttle Cables

Changing the fluid solves plenty of transmission issues but if the problem of automatic transmission won’t shift into 3rd gear persists, the parts you should check are the throttle cables. A defective cable with excessive slack is likely to create issues with smooth shifting of the gears. It may also totally stall the shifting.

Examine the PCM

automatic transmission wont shift into 3rd gear
A defective PCM could be the reason too. Source: AutoYas

A faulty PCM (powertrain control module) will affect the transmission performance because it controls the gearbox mechanism in most car models. The PCM will have no input if the speed sensor fails. In that case, the transmission will not shift properly. To solve this problem, you have to check the speedometer to see that it is functioning. Otherwise, replacing the VSS could be the solution.