Transmission Issue?

I have an issue with my 2009 Chevy Aveo5 LT.
I hope someone can help me with this.
Any assistance would greatly be appreciated.

My check engine light came on so I decided to go to AutoZone to pull the codes.
On my way there I noticed something unusual.
I came to a stop sign and then turned left on to a highway.
When doing so, I floored the accelerator and gave her all she’s got just to see how it would perform.
As the automatic transmission shifted into second, I got the sensation that the engine was trying to stall.
I let off the accelerator a little bit which seemed to make the car operate normally.
On my way back from AutoZone, I tried the same test again.
This time, I think the “stall issue” was in fact the transmission not shifting from second to third (drive gear) as it should.

I mention all this because the codes AZ pulled were transmission related.
The first code was P0700 and was defined on their scanner as follows…Transmission control module (TCM) requested mil illumination (whatever that means). The TCM has detected an emission related fault. Probable cause… check other service codes first.

The second code was P0706 and was defined as…Transaxle range switch performance.
During engine start up the ECM detected an input other than park or neutral.
Probable cause…failed transmission sensor and/or open or short circuit condition.

Does anyone know what the real cause and fix is for this?
What’s the best way to troubleshoot this further?
Could it be as simple as changing out the transmission fluid/filter?

put the 706 first. the 706 caused the 700, I would either get real into it and check to see if you have voltages between shifts in your range sensor circuit or just replace the range sensor and take a shot in the dark.

Can you tell me how to check for voltages?
Where is the range sensor located?

Looking on the AutoZone website, I see they have what is called a transmission speed sensor. Is this the same thing? Looks overpriced to me.
http://www.aveoforum.com/forum/attac...eed-sensor-jpg

Should be a shift range sensor, I would never look at part store prices, maybe rock auto, but never part stores, check eBay?

I'm not certain where the safety switches are that ensure the shifter is in N or P, but I'd sure start by looking for them by taking apart the shifter console.

Can anyone tell me the part number for the sensor? I spoke to a Chevy dealer today who said this may be covered by the power train warranty however he would need the part number and my VIN. Otherwise I will have to drop off my car so they can charge me to figure it out.