Odd transmition stuff

Ok when i get on the highway, my blazer will not shift into overdrive. It gets to 4th fine, but it will ride at about 2400 rpm at 70, it simply doesnt shift into overdrive. Any answers???

Welcome to AF.
What year make and engine and transmission and mileage and how many doors?

From a stop and normal take off count the upshifts and at what speed does it shift up?
Post back car info and shift info.

Can you feel a tcc lock up?
Are you sure you are not confusing lockup with OD?
MT

Its a 98, has 217,000 miles, 4.3 l v6, 4 door 4 wheel drive, transmission is only 50,000 miles old though, i am not sure of the exact type, I guess it is the standard that they but in chevys because we got it rebuilt at the dealer.
I did some research on it and a " multiple cylinder misfire" sounded like my problem, do you know much about this?

It shifts to second at about 17 to 20, 3rd at obout 35 and into 4th at around 55 to 60, but then it rides in 4th even up to 80, which is about where it stops accelerating due to it not shifting into overdrive. It was odd though, the other day, when it was about 50 degrees, it went into overdrive ok. But any cooler than that it has its problems.

I am not to sure if i am confusing lock up with overdrive, all i know is after 4th it will shift again for a " highway type gear" I am not farmiliar with lockup

If it shift into all four forward gear you have OD.
To feel for lockup at a steady speed around 60 MPH with no one behind you with left foot push brake pedal down enough to turn on brake ligh.
then you should feel it kick out of lockup and the rpm jump up around 300 rpm.
The let back up on brake pedal and you should feel it go back into lockup and rps drop around 300 rpm.

When engine is cold it may not go into lockup.

What is the rpms at 60 and 70 and at 80 MPH

If it is not working good get it on a transmission/engine capable scanner and check for codes and post back any codes.
Or run it by a repair shop and let them test drive it.
Are you sure transmission is not slipping in OD.
Watch the rpms for a big jump.
Have you checked fluid level in transmission or has the transmission ever beed serviced.

Its a 98, has 217,000 miles, 4.3 l v6, 4 door 4 wheel drive, transmission is only 50,000 miles old though, i am not sure of the exact type, I guess it is the standard that they but in chevys because we got it rebuilt at the dealer.
I did some research on it and a " multiple cylinder misfire" sounded like my problem, do you know much about this?


If it is missfiring the check engine light will flash.
Also if a missfire problem you will have codes past present or history.
Is or does the check engine liight come on?

How is the tune up end?
A engine has to be running good for the transmission to work good.

Post back any code no.

ok, i will try that for sure. I am changing out the spark plugs and connection wires tonight because that is what the NAPA guy said to try. I will try what you said tonight, thank you very much.

The check engine light does come on.

The check engine light does come on.
Was codes cleared?

What are the code no?
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