transmission stuck in 3rd. gear

[stevesnider]

My 1997 gmc shifts great until overdrive. Than it won't shift up at 55-60 mph. any suggestions?

Thanks ,Steve

[charliepeterson]

Look for any codes first. It doesn't sound very good though.

[stevesnider]

Thanks Charlie I'll get codes checked in the morning .
The only codes lately is p380 for the glow relay.
I did get ahold of my trans. mechanic and he said the same thing ,check codes.
Thanks , Steve

[Marty Lau]

There are a couple of shift sensors on the out side of the transmission on the driver side. One is 1-2 and the other is 3-4. One of those could use either a cleaning or replacement. They are about $30 each and one bolt holds them in place. They are easy to remove and replace. Also there are other changable items access able if you drop the pan. I had a stuck in 2nd and changed all of it. So if could be something there.

[stevesnider]

Solved problem! I had to unhook the temp sensor the other day to start the truck and forgot to hook it back up . That must have messed with the computer.Today afer getting it started I hooked the temp sensor up and took a run around the beltway to auto zone to get codes ckecked. The truck ran fine going over and comming home.

I want to thank you guys for the suggestion , Steve