Car Won’t Shift into Gear: Automatic Transmission Troubleshooting
When your car won’t shift into gear, it can be a frustrating and potentially dangerous situation.
If you’re experiencing this issue, there are a few things you can check to try to troubleshoot the
problem.
Check the Transmission Fluid Level
The first thing you should check is the transmission fluid level. If the fluid level is low, it can
cause the transmission to slip and not shift properly. To check the fluid level, follow these steps:
- Park your car on a level surface.
- Turn off the engine and allow it to cool for a few minutes.
- Locate the transmission fluid dipstick.
- Pull out the dipstick and wipe it clean with a rag.
- Reinsert the dipstick all the way into the tube.
- Pull out the dipstick again and check the fluid level.
The fluid level should be between the “full” and “add” marks on the dipstick. If the fluid level is low,
add more fluid until it reaches the correct level.
Check the Transmission Filter
If the transmission fluid level is correct, the next thing you should check is the transmission
filter. A dirty filter can restrict the flow of fluid and cause the transmission to slip. To check the
filter, follow these steps:
- Park your car on a level surface.
- Turn off the engine and allow it to cool for a few minutes.
- Locate the transmission filter. It is usually located on the side of the transmission.
- Remove the filter and inspect it for dirt and debris.
- If the filter is dirty, replace it with a new one.
Check the Transmission Solenoids
Transmission solenoids are small electrical devices that control the flow of fluid in the transmission.
If a solenoid fails, it can cause the transmission to slip or not shift properly. To check the solenoids,
you will need a multimeter. Follow these steps:
- Park your car on a level surface.
- Turn off the engine and allow it to cool for a few minutes.
- Locate the transmission solenoids. They are usually located on the side of the transmission.
- Disconnect the electrical connector from the solenoid.
- Set your multimeter to the ohms scale.
- Touch the multimeter probes to the terminals of the solenoid.
The solenoid should have a resistance of between 10 and 20 ohms. If the resistance is higher or lower than
this, the solenoid is faulty and needs to be replaced.
Check the Transmission Control Module (TCM)
The transmission control module (TCM) is the computer that controls the transmission. If the TCM fails,
it can cause the transmission to not shift properly. To check the TCM, you will need a scan tool. Follow
these steps:
- Connect the scan tool to the OBD-II port on your car.
- Turn on the ignition.
- Select the “Transmission” menu on the scan tool.
- Check for any trouble codes that are related to the transmission.
If there are any trouble codes stored in the TCM, you will need to have them diagnosed and repaired by a
qualified mechanic.
Other Possible Causes
In addition to the above, there are a few other possible causes for a car not shifting into gear with an
automatic transmission:
- A faulty torque converter
- A worn-out clutch
- A broken transmission case
If you have checked all of the above and your car still won’t shift into gear, you will need to have it
diagnosed and repaired by a qualified mechanic.
Conclusion
If your car won’t shift into gear, it can be a frustrating and potentially dangerous situation. By
following the troubleshooting steps outlined above, you can narrow down the possible causes and get your
car back on the road.
