1998 Blazer Transmission Problem

My 1998 blazer has continued to be a pain....currently I am experiencing transmission problems and have no idea what is wrong. On long trips, over 50 miles of highway driving, when i stop with the transmission hot and take off agian the first to second, and sometimes second to third, shift hits extremely hard.....however, if I drive the vehicle around town i can run all day with prefects shifts. The check engine light came on and I took it to a mechanic. He said that it was the transmission shift seleniods so I had them replaced along with a transmission flush. It seemed to cure the problem for about a week, and now the light is on agian with the code reading "transmission component slip" and the problem is once agian occuring. It was suggested that i rebuild the tranny, but I am wondering if anyone has any ideas as I can drive it around town with no problems?

This is a known issue with GM vehicles that have the 4L60E transmission. The issue normally presents itself after the transmission has had time to warm up and has been driven approximately 50 - 60 MPH. At highway speeds the torque convertor locks up for increased efficiency and so that it generates less heat. The lockup is accomplished by a solenoid in the tranmission's valve body which applies the torque convertor clutch (TCC). The solenoid and valve body itself are made of different metals which cause them to expand and contract at different rates. This constant variance in rates causes the valve body to wear away. The wore valve body allows transmission fluid to slip past the solenoid, causing a weak TCC apply. This weak apply is detected by the tranmssion as a slip. When a slip is detected the computer increases the line pressure to the shift solenoids to make the shifts firmer to minimize damage. This increased line pressure is what causes the hard shift that you feel, it is most noticable from 1st to 2nd gear. If the transmission detects the slip on two consecutive trips it will illuminate the "Check Engine" or "Service Engine Soon" light and store the code P1870.
If you ignore the problem, you will end up damaging your transmission and it will require a rebuild or replacement. However, if you catch it in time you can generally save your transmission. There are two ways to remedy the problem. 1) Replace the valve body. (GM has a new updated one) 2) Repair your current valve body, this can be done with special repair kit available through Sonnax.

Thank you very much, it makes a lot of sense. Truely, thank you! Your the only one that has been able to explain this to me....

My 1998 blazer has continued to be a pain....currently I am experiencing transmission problems and have no idea what is wrong. On long trips, over 50 miles of highway driving, when i stop with the transmission hot and take off agian the first to second, and sometimes second to third, shift hits extremely hard.....however, if I drive the vehicle around town i can run all day with prefects shifts. The check engine light came on and I took it to a mechanic. He said that it was the transmission shift seleniods so I had them replaced along with a transmission flush. It seemed to cure the problem for about a week, and now the light is on agian with the code reading "transmission component slip" and the problem is once agian occuring. It was suggested that i rebuild the tranny, but I am wondering if anyone has any ideas as I can drive it around town with no problems?
Had this same problem with my 98 blazer I installed a revised valve body and it cured the problem. It's a pretty tough job if you don't have a hoist to install one but is doable. Sometime in 2000 these where installed with revised valvbody's... I'm still waiting to see if I have a revised valvbody in my 2000 I hope so!!