I have a '99 Chevy Blazer. 4.3 V6 Automatic. The transmission is shifting at higher RPMs then normal. I gets up to about 20mph before it shifts into 2nd gear. I have tried disconnecting the battery for a while and that didn't help. I was wondering if this could have anything to do with the Thorttle Position Sensor or dose something else control when the transmission shifts?

Vss

What about the VSS?

Vehicle speed Sensor on the Transmission.

So you think that it is the VSS and not the Throttle Position Sensor?

yes, transmission can't tell how fast you are going.

First off, try resetting the computer by removing the negative battery cable for 5 minutes.

I tried disconnecting the battery. The SES light was no longer on after I reconnected it, but it is still shifting wrong. How hard is it to replace the VSS?

yes, transmission can't tell how fast you are going.

First off, try resetting the computer by removing the negative battery cable for 5 minutes.
All cars sold in U.S.A. since 1996 use the OBD2 computer system with a non-volitile memory ,just unplugging the battery for 5 minuets will not reset all your codes,that must be done with a diagnostic computer, thanks to our federal goverment and Al Gore gets a big share of the credit

I replaced the Throttle Position Sensor and that fixed the problem. It is shifting perfectly now. Thanks for all of your help.

All cars sold in U.S.A. since 1996 use the OBD2 computer system with a non-volitile memory ,just unplugging the battery for 5 minuets will not reset all your codes,that must be done with a diagnostic computer, thanks to our federal goverment and Al Gore gets a big share of the credit

Nope, you unplug the battery for 10-15 minutes and everything is gone.

Don't argue against me, I done it several times and I own a scanner.