i have a 2001 ford expedition that is not shifting into 4th. it is a 4r100 tranny. it is throwing a p0783 code. i recently replaced the solenoid pack, do not remember that code(p1746?). also flushed tranny. any ideas? is this thing done?

 

Thats a 3-4 shift error code. Could be a sticking 3-4 shift solenoid

 

i already replaced the solenoid assembly so i believe that the problem is not solenoid related. can any explain the difference between pulse width modulation vs. unmodulated when it comes to the pressure control solenoid?apparently this year had both set-ups not certain i got the right solenoid pack.