Skip the auto shop - Our mechanics make house calls

Q: Truck will shift sometimes then it doesn't shift. If you wait a while it will shift again. We are trying to figure out what's going on

asked by on

Truck will shift sometimes then it doesn't shift. If you wait a while it will shift again. We are trying to figure out what's going on

My car has 128795 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. The first thing ...

Hi, thanks for writing in. The first thing I recommend is to make sure the ATF (automatic transmission fluid) is full.

Does the transmission shift up a gear or two and stay in that gear, or does it drive fine for a bit, then stop shifting until you turn the car off or sit still with the motor running? Or, do you continue to drive and eventually it begins shifting again. Are there any codes?

What I would do if I were diagnosing your truck would be to connect a scanner and study the data while driving to know what is going on. Without said data and not quite being clear about what is happening, it comes down to solenoids or sensors that the TCM (transmission control module) uses to calculated shift points based on load values determined by the PCM (powertrain control module).

I’m afraid all I can offer you at this point is suggesting you make sure the fluid is full and clean. If it isn’t clean, begin by replacing the filter in the pan and do a transmission fluid exchange, not just pan drop with a drain and fill. This doesn’t get all the ATF out of the transmission, and when there are problems, it pays to be as thorough as possible.

I recommend the following inspection if you should need further assistance: Car hard to shift

Hope this helps and best of luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car hesitating and wanting to stall

Oxygen sensor failure is not too common on your vehicle. Just because a code for the oxygen sensor is present, it does't mean the sensor is bad, just that one of the parameters it reads is out of specification. For...

Q: Need help finding the name of the plastic ring that holds the shifter in place

Hi there. The part that you are looking to replace is called a shifter seal and there is also a shifter spacer. The spacer is the plastic ring that hold the shifter in place. The metal shifter seal is the...

Q: Taillights don't work. 1998 GMC C2500

Hello there. Faulty tail lights are a common repair on the GMC C2500. There are a few possible reasons for the brake lights to work but not the taillights. The most common would be a wiring fault, bulb failure, switch...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.