So all the sudden my truck upshifts through the gears very quickly. Even just driving 20-30mph it goes up all they way to 4th gear. If I mash on the gas it will not down shift. It only goes back to first gear if I damn near stop. This just started happening instantly; it was not gradual. everything was fine one minuit then it started doing this. What should I look for? Is it just trash in the fluid? A solonoid? Sensor?

 

You have a fault in the trans circuits. The od cancel light should be flashing.you will have to get a good shop or dealer to pull the code and see what the issue is.

It is shifting that was as it is in "limp home" mode.

 

No lights flashing. I guess I will find someone to take a look.

 

I have a tuner that reads codes. Will it read tranny codes?

 

Does the od cancel light work if you disable od? I am willing to bet it does not if when it is in limp it does not flash.either way you have codes. What tuning device do you have?

 

Super chips micro tuner. I just drove the truck around the parking lot here at work and couldn't get it to do it. Hit the OD button on and off a few times with no lights. I'll have to see what it does after work?

 

Well, oddly enough; the truck fixed itself. Drives and shifts as normal. My guess is that trash got in a line and caused it to go into limp mode? When I turned the truck off and let it sit the debris fell back in the the pan??? Thats my uneducated transmission guess anyway.

 

If your od light does not work then you should have it checked for codes. The trans could be warning you of something wrong, it could be a cheap repair now or a pricey one later. I don't really believe that crud worked its way out.

 

Yeah these transmissions can get expensive, very quick. It would be worth it to check for codes. The peace of mind alone would be worth it.

 

When you say OD light are you referring to the one on the end of the shifter handle? OD off?

 

You HAVE a problem. Yes the shifter when you cancel od the "off" lights up.
That will flash when there is an issue. when you key off and back on it can restart but once its up to temp my bet is it messes up again.

 

Nothing flashing. I drove it for quite a while after work. I am going to see a tranny guy here in ft worth to take a look.

 

Most likely a problem with the VSS or the wiring to it .Hard part problems usually don't come & go ..

 

Does the od light work?

 

Yes, it comes on if I press it.