Transmission shifting hard

I have a 1997 Blazer with 58000 miles. When I drive on short to medium drives (under 20-25 miles) the transmission shifts fine. When I go on longer drives it starts to shift hard between 1st and 2nd gear and a little lighter between 2nd and 3rd gear. Then shortly after that the "service engine soon" light comes on for about 2 days then shuts off. I just had the transmission serviced and they found nothing wrong with it. Does anyone know what else I might check?

I don't know why it would only happen on long trips, but if the transmission is fine, check your linkage. Also, post back and describe in a little more detail what it feels like to shift. Does it make noise? Does the shifter pop out sometimes, etc.

If the SES light came on did they tell you what codes where stored?

When the transmission shifts from 1st to 2nd it feels like if you popped the clutch (even though it is an automatic). Then from 2nd to 3rd it is less and does not jerk but you feel it shift hard. Then from 3rd to 4th you do not notice a difference, it is a smooth shift. Then when you turn the vehicle off it shifts smooth then like nothing happened. The transmission does not make a noise and the shifter does not pop out. The transmission place I took it to never told me what codes it was putting out. Thanks!

Oh it an automatic! First check your ATF and make sure its full. Also, do you mean it shifts hard on its own, or when you manually shift it?

It shifts hard on its own and the tranmission fluid is full.

My 1998 Blazer started to do the same thing a week ago. I took a 200 mile drive to give my Grandmother a drive home. When I got home, my truck would jerk when going into 2nd gear. I also noticed that the undercarriage was caked with a wet substance which I now assume was ATF. Now, I can drive it around the house just fine, but if I go on the highway, it will start to jerk again going into 2nd.

I have 2 questions.

1) Will simply filling back up with ATF fix the problem?

2) Is my Tranny hosed?

Thank you in advance for any input

Bfons

I had the same problem. It turned out to be the Throttle Position Sensor. If I had it idling in drive on a hill, it would stall out, sometimes. Also, while driving (no matter long or short) it would shift REAL hard from 1st to 2nd, then slightly easier from 2nd to 3rd. Definitely get that checked out.

Hey, i had the same problem on my '99. I was having clutch slippage or something. The transmission guy explained it but i didnt really understand. He put in a valve box that increased the pressure on the clutch when changing. He said that this was a normal procedure. Hope this helps.