The Common Causes of Auto Transmission Not Being able to Shift into Third Gear

When you drive your car, you expect that the transmission will shift seamlessly between gears, but that’s not always the case. Transmission problems can cause shifting issues between gears. If the auto transmission won’t shift into third gear, you could be looking at a multitude of problems.

Degraded transmission fluid is often the reason for problems with automatic transmission shifting. A bad torque converter, an inoperative PCM, or damaged shift solenoid could cause problems with the automatic transmission. These issues should be addressed immediately. 

In this article, we discuss the reasons why your automatic transmission won’t shift out of second gear. The problem can also be fixed.

Causes of Auto Transmission that Won’t Shift into 3rd Gear

1. Contaminated Transmission fluid

To lubricate moving parts and gears inside the transmission, you will need to use transmission fluid. It operates much like motor oil, except it’s designed specifically for the transmission. As the fluid ages, dirt and other particles build up.

It is much harder to shift normally when the transmission fluid has been degraded. It can also damage the transmission permanently if it isn’t flushed and replaced promptly. Check your vehicle owner’s manual to find out how often the transmission fluid should be replaced. These guidelines will ensure that your transmission is in good health. 

2. Malfunctioning Shift Solenoid

There are many shift solenoids that change the gears for you inside the transmission. Failure of one or more of these solenoids can lead to shifting issues in any gear. It's also possible for the TCM to change the 3rd and 4th gears.

The easiest way to reach the shift solenoids is by removing your valve body. In other cases, however, it may be necessary to completely remove the transmission and disassemble the transmission.

RELATED : 7 Warning Signs You Might Have a Shift Solenoid

2. Bad Torque Converter

This is the part that engages and disconnects the transmission from an engine. It contains vital parts, including a motor and turbine. 

The torque converter may fail and cause the transmission to slip. This can cause difficulty shifting to a specific gear. 

4. Faulty TCM or PCM

Transmission performance can be affected if the PCM/TCM fails. The TCM or PCM controls the gearbox, and acts as the brain to operations.

Other symptoms may appear as the PCM fails. It’s common to see the Check Engine Light and experience erratic shifting patterns. The car might go into Limp Mode until it is fixed.

What to Do When Auto Transmission Won’t Shift

1. Take a look at the Fluid

Check the fluid first if you experience any issues with your transmission. You will need to take out the dipstick to check the fluid levels if your vehicle does not have a sealed transmission. To get a more precise reading, wipe off the dipstick and place it back in. If the levels are low or below the fill line, it’s time to add some fluid.

Be sure to check the condition of your transmission as well as how much fluid is present. A lot can be learned from the color of fluid. It will turn a bright red-pink color if the fluid is in good condition. As it gets older, it starts to turn brown, indicating it’s time for a transmission fluid flush. You could have bigger problems if your fluid turns black, dark brown, has metal shavings or has a burnt odor. 

RELATED: Transmission Fluid Color Chart (5 Different Colors)

2. Look up Trouble Codes

When there is a fault in the car’s computers, an error code is set. With an OBDII scanner, you can view these codes to learn more.

Although each vehicle has its own codes, there are some universal ones. You might find a P0606 code or P0113 code to indicate if the PCM is not working properly. Whatever code you see, it’s possible to do some research online and hunt down the trouble for a quick fix. 

3. Ask for help

Sometimes, even though you're a professional mechanic, there are still problems that you can't solve. If you see a code that you don’t know how to resolve or you are unsure why the transmission is acting up, it’s best to get professional guidance.

It is possible to prevent more serious transmission problems by getting prompt help. Transmission damage can worsen if the problem is not addressed immediately. It is possible to resolve the issue quickly by following these simple steps.