trans stuck in third gear

[overdoseheroin]

i just picked up an auto awd for a few hundred and runs great, i bought it for winter and this is the first auto dsm i have ever had or dealt with so i know nothing about the tranny. everything was cool and it was downshifting and everything great, then all of a sudden its stuck in 3rd gear, and will not downshift wether i try it manually or not. i was looking up threads and found a few that talked about "limp mode" but i cant get a good explanation as to what it really is and if theres something that can fix my problem. any help would be great, thanks.

 

[92awdgsx]

You'll have to try to pull some codes and see what it says. It goes into limp when the TCU thinks there is something wrong with the tranny.

http://www.plymouthlaser.com/tcucodes.htm

 

[overdoseheroin]

i hooked my logger up to it and ran a test and came up vehicle speed sensor, i erased the code and its been fine ever since.