Automatic Transmission Won’t Shift into the Third Gear (Causes)

Problems with the transmission can lead to costly repairs. A car that does not go into third gear is therefore something you want to fix as soon as possible before something else breaks down. Read on

Automatic Transmission Won'T Shift Into The Third Gear

When you drive your car, you expect that the transmission will shift seamlessly between gears, but that’s not always the case. If there is a problem with the transmission, it could begin exhibiting trouble shifting between gears. If the auto transmission won’t shift into third gear, you could be looking at a multitude of problems.

Issues with shifting the automatic transmission often relate to degraded transmission fluid. However, the transmission could also be struggling because of a bad torque converter, a faulty PCM or a damaged shift solenoid that needs to be repaired. 

In this article, we discuss the reasons why your automatic transmission won’t shift out of second gear. We also look at the steps you can take to repair the problem.

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

1. Contaminated Transmission Fluid

Drain Transmission Fluid

Transmission fluid is needed to lubricate the gears and moving parts located inside. It operates much like motor oil, except it’s designed specifically for the transmission. When the transmission fluid gets old, dirt and debris begin to build up in it.

Degraded transmission fluid makes it much more difficult for shifting to occur normally. 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. Following these guidelines can ensure the transmission remains in optimal health. 

2. Malfunctioning Shift Solenoid

Symptoms Of A Bad Shift Solenoid

Inside the transmission, there are several shift solenoids changing the gears automatically for you when the TCM decides to do so. If one of these fails, it can cause shifting issues with any gear and 3rd gear is therefore very possible.

The shift solenoids are most often reached by removing the valve body by removing the transmission oil pan of your car, but in some cases, you have to remove the transmission completely and take that transmission apart.

RELATED: 7 Symptoms of a Bad Shift Solenoid

2. Bad Torque Converter

Torque Converter

The torque converter is responsible for engaging and disengaging the transmission from the engine. It includes vital components, such as a stator and a turbine. 

Any of these parts on the torque converter can fail, leading to a slipping transmission. It can also lead to trouble shifting into a particular gear. 

4. Faulty PCM or TCM

Transmission Control Module

When the PCM or TCM fails, the transmission performance is degraded. The PCM or TCM is responsible for controlling the gearbox and it acts as the brain for operations.

As the PCM starts to fail, you may notice other symptoms as well. It’s common to see the Check Engine Light and experience erratic shifting patterns. The vehicle might even go into the Limp Mode until the problem is resolved.

What to Do When Auto Transmission Won’t Shift

1. Check the Fluid

The first step when you are having any trouble with your automatic transmission is to check the fluid. Unless your vehicle has a sealed transmission, you will be able to pull out the dipstick and read the levels. Make sure you wipe it off and put it back in for a more accurate reading. If the levels are low or below the fill line, it’s time to add some fluid.

While you are checking how much fluid there is, be sure to also check the condition. The color of the fluid offers a lot of information about the health of the transmission. If the fluid is good, it will be a red-pink color. As it gets older, it starts to turn brown, indicating it’s time for a transmission fluid flush. However, if the fluid is black or dark brown and has a burnt smell or metal shavings included, you could be looking at larger problems. 

RELATED: Transmission Fluid Color Chart (5 Different Colors)

2. Read Trouble Codes

When there is a fault in the car’s computers, an error code is set. You can read these codes and learn more about the problem with an OBDII scanner.

Each vehicle uses different codes, although there are some that are universal. For example, you might see a P0606 or P0113 code if there is an issue with the PCM. Whatever code you see, it’s possible to do some research online and hunt down the trouble for a quick fix. 

3. Get Help

Even if you are a skilled mechanic, you might encounter a problem that is over your head. 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.

In many cases, prompt attention can alleviate larger transmission problems down the road. The longer you let the issue continue, the more damage might occur to the transmission. Hopefully, the problem is related to a simple fix that can be resolved quickly.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.