Truck just revs after driving fine, code P0300

Good morning,

I would start by changing the oil and filter in the transmission. The filter may be partially clogged, not allowing pressure to the valve body.

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

https://www.2carpros.com/articles/automatic-transmission-problems

The 300 code is for the engine. It is a misfire code. I attached a guide for possible issues causing the code.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Roy

Thanks. I'll let you if it worked.

You are welcome.

Always glad to help.

Roy

I have one more question now. I have the vehicle listed above LT and also, I have a 2004 trailblazer LS the LS blew the rear differential out. would I be able to use the rear differential off the LT for the LS?

Yes, it will but you need to confirm the gears are the same ratio.

Remove the rear cover and check the numbers off the back of the pinion gear.

https://www.2carpros.com/articles/differential-service

Roy

Okay, I will check it out I know the LS is G80 GU6 just have to check the LT. thanks again.

You are welcome.

Let us know if you have any other questions.

Always glad to help.

Roy

So, both of the vehicles say G80 and GU6, so that means they are both 3.42 with the locking right?

Did you remove the back cover and check the numbers on the back of the pinion as I suggested?

Roy

Not yet, taking kids to school and when I get back, I'll do that.

We will be here for you.

Roy

Okay. Sorry, I got a little busy today. so, I took the transmission pan off to check and drain the fluid and there is silver all around in it and the magnet was covered to the max it seemed like. So, I'm assuming the transmission is going out or is bad, right?

Correct.

You need either an overhaul or replacement. There is no easy fix when it is coming apart internally.

Roy

Yea, that's exactly what I was thinking myself. The guy I bought it from said he's willing to get another transmission for it and have it put in or he would buy one and I could put it in. I'm thinking I might have him either buy it and have it put in or just give me the money back.

If you are keeping this long-term, I would consider having it overhauled and done correctly. Let him contribute to that cost for you. That way, you have a warranty if there is a problem.

Roy

I really appreciate the help you gave me. If I ever need help again, I will be sending it right on this site. again, I really appreciate everything you have done.

Thank you for the kind words.

We are always glad to help.

Roy

https://www.replicarclub.com/how-to-reset-transmission-control-module-chevy/

Does this actually work?

You can try it but no, it only erases the memory for the shifting points and the modules will relearn the correct shift points.

It has no effect on your current issues.

Roy

Okay, thanks. now I'm having a hard time see what type of transmission I need for it. It has 2hi awd 4hi and 4lo. Could you possibly tell me what kind I need so I can tell the guy I'm not around the truck at the moment or I would check.

Did you go to the web site I sent you for the transmission?

Roy

I forgot about that. sorry, the past couple days have been pretty hectic for me. I will check it out thanks again.

No problem.

Let me know if you have any other questions.

Roy

Will do, thanks.

Ok I got 1 more question ive looked up from a few different forums about the transmission in my 2004 trailblazer and the 2005 trailblazer and from what I read they are the same transmission I just want to double check and ask your opinion on it its just incase the transmission the guy has (who I bought the truck from has the wrong one) I juat want to make sure if they r compatible with each other even though the 05 is awd and the 04 is 2wd