Transmission not shifting from first to second

THKMASJ

MEMBER
2004 CHEVROLET TRAILBLAZER
4.2L
6 CYL
4WD
AUTOMATIC
122,000 MILES

So my truck started driving weird and will get up to 20 mph and the RPM's will go up and unless I take my foot off the gas. It will not shift into gear however after that it shifts fine through all the other gears. I’ve replaced several parts and still having the same problem.

3 Replies

4DRTOM

MECHANIC
467 POSTS

Hello,

Here is a couple links to our transmission servicing articles that may help out with this issue:

https://www.2carpros.com/articles/automatic-transmission-problems
https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

I'm going to need a bit more information on this to help out fully. As for your symptom, did this come on quickly just one day or it was happening the day before it was fine and have you noticed any spots of oil under the car at all? What parts have you replaced trying to solve this? You should scan the car to see if any codes come up as well. It could be one of the shift solenoids have clogged or gone bad a good scanner should pick this up with a code if it has in fact failed. Check the fluid level and inspect it for looking dark and smelling burnt too. This could be something a regular maintenance service will handle and hopefully not a transmission overhaul.
Let us know how you do after reviewing the articles and getting a scan done.
Tom
2carpros

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Friday, November 27th, 2020 AT 9:41 AM

THKMASJ

MEMBER
2 POSTS

Yes, this issue started out of nowhere and I did scan and the only code I got was solenoid a stuck on. Since then I’ve replaced solenoid A and B I also replaced the accumulator one and two and the transmission manifold pressure switch. The fluid is clean and there were no medal shaving in the pan. Also after replacing the solenoids I did use test leads with a 9 V battery and they clicked as they are supposed to.

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Friday, November 27th, 2020 AT 10:14 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

I attached some possible issues for not shifting for you. It could be the valve body.

As far as the solenoids, did you verify power to the solenoids in the truck with the pan down? I attached a wiring diagram of the transmission as well.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

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