strange transmission shifting

[Y2KpewterZ]

2000 z71 Tahoe... when i floor it from a 10-15 mph roll the trans downshifts as it should, but then instantly upshifts. I noticed it tonight, when i wanted to hear my sweet intake (lol). I guess it went into first and as soon as it hit about 3000rpm it upshifted. Are there kickdown cables on these? As far as i know theyre computer cobtrolled..

 

[SunlitComet]

negative ghostrider. no tv cable on you hoe, only shift cables. check for stored code type on the pcm that do not illuminate the cec that may be doing it if it is happening on wot.

 

[Y2KpewterZ]

I know a pcm will store codes and not illuminat the check engine light, but will a typical code scanner still read the stored codes?

 

[SunlitComet]

you know it is possible some my not. if you go to a parts store to have it done go thru the menu with them to see what it can do.

 

[Y2KpewterZ]

Ill take it to a shop. Have to stop by one tomorrow anyways for a state inspection. I was curious though because I have a Actron CP9125 PocketScan Code Reader i keep in the truck at all times.

 

[SunlitComet]

manual say active or pending but not stored.

 

[Y2KpewterZ]

Checked stored codes. Had two of them
1, being for a stop lamp circuit (?) My brake lights function properly..
2, being a rear abs sensor. No abs light and my abs functions properly (as tested in the snow)

Nothing related to transmission.

 

[SunlitComet]

how about the code numbers please.