Looking for a little guidance, I have a 2003 Trailblazer with 90k miles. The transmission shifts pretty hard at times when the cruise is set. Another instance is when I am traveling around 50 mph steadily the rpm's fluctuate a little and it seems to bogg down going up hill until it decides to shift down. Feels like it waits till the last minute to shift.

Anyone else know of this or what could be the issue? i have taken it to a few different mechanics and they couldn't diagnose the problem. And of course, it doesn't do it when they test drive it.

Is this a trainy issue or electrical (i have heard maybe a coil issue?)


Thank you in advance.

 

Does it only do it with the cruise control on or does it do it at random?

 

It will shift hard up hill with the cruise on like it doesnt want to shift yet until it really needs to.

rpm's fluctuate with cruise at times but more when i am steady peddling around 50 mph in 3rd gear. and have to manually shift down at times to to break it up or pedal harder.

Hope this makes sense.

Regard,
Novas.

 

My 03 Trailblazer also had shifting problems. Had to have the transmission rebuilt at 52,000 miles. It was a bad valve body. You might have something similar. If it only does it in cruise control then you have a problem with the cruise control.

 

Not just while the cruise is on. Cruise works well when this issue is not happening. is a valve body repair mean i have to rebuild the entire transmission?

 

You have to pull the transmission pan and the valve body is right there along with what seems to be a hundred wires. That would be a quick fix, but there are probably other things wrong with it.