Shifting Problems

JonStewart · May 25, 2009

Hi there. Im new to this site but hope to use it alot. I have a 2006 gmc sierra and it isnt shifting right. Itll start off in second as it should, then it doenst shift into second. It revs up to about 4000 RPM (or until there is enough revs to shift into third). Ive put my uncles scanner on it and it says i dont have second gear. I cant stomp right down on the gas because it will drop down to first and wont shift and will rev up to 6000 RPM's which before the rev limiter would only allow it to go to 5200 RPM. It will shift back out first once i let off the gas, but as soon as i hit the gas hard enough again it will drop back down to first. So i changed the 1-2 shift solenoid but that didnt work. I was wondering if anyone has had this problem or possibly give me advice as what i could do. Ive taken my truck to a tranny shop and they said $400 and they could take the tranny out, take it apart and tell me what i would need to fix it, or i could take it out myself and only pay $80 for them to take it apart and tell me what i need. I would just do the second option but i have no way of bringing them tranny if i did that and money is tight enough right now. I was thinking i could possibly splurg for a rebiuld kit but i dont know which tranny i have. Does anyone know how i would go about figuring this out for myself? Oh and no there is no warrenty left on it. Any help would be greatly appreciated.

masterfoxscout · May 25, 2009

Hmmm. I'm not sure. Someone will be able to help. They guys here are incredible.

Also, welcome to the site.

Draenor · May 26, 2009

Do you have the correct amount of fluid?

What is the exact DTCs you are reading?

JonStewart · May 27, 2009

Do you have the correct amount of fluid?

What is the exact DTCs you are reading?

Yes, i remembered to check the fluid. What is a DTC though?

txab · May 27, 2009

Do you have the correct amount of fluid?

What is the exact DTCs you are reading?

Yes, i remembered to check the fluid. What is a DTC though?

It's the trouble code that your scanner should have given you.

green 788 · May 27, 2009

What does the truck do when you shift it manually? (selecting 1, then 2, then 3, then D)?

Is this a 1500, or a heavier truck? (we don't know which transmission you actually have).

Is it a 2 or 4 wheel drive?

How many miles on this truck?

Is your speedometer reading correctly, or is the needle twitching or dropping down, etc?

These are important questions to have answered before any cogent advice can be given...

Dan

JonStewart · May 27, 2009

When done manually, it does the same thing. nothing happens when i put it in 2. Yes its 1500 and 4 wheel drive. 76500ish kms on it.

green 788 · May 28, 2009

That's pretty low mileage, all things considered...

I assume your speedometer is fine, so the speed sensor working that ought to be okay.

I don't know about your particular year model, but you can look on the transfer case for a speed sensor there, which could be a secondary speed sensor being that the truck is a 4WD. If you unplug that sensor, the truck should go into a default shift setting, working off the tachometer instead of the speed sensor. See if the truck shifts normally then (it might shift a little snappy). If it does, then you probably have some sort of electronic problem keeping the truck from acknowledging the 2nd gear shift signal.

I doubt if it's a major internal transmission problem. I would rule out a speed sensor problem first off, and yes, as suggested above, have the ECM scanned for trouble codes.

Write back with an update.