There will be a code present during limp mode ,First determine if there is a code setting if there is corect whatever condition it indicates , if theres not a code then heres some electrical fault causing loss of B+ to the trans and the wiring plugs grounds will need to be checked

 

its the po751 and po757 for the 2001-2002 cars that needs to be turned off. For the earlier cars its something like 18xx or something like that, ill try and find it for you