Dodge Repair: truck wont shift, transmission cable, brake switch

Question
QUESTION: I have a 2004 ram 1500 5.7 hemi that won't shift.

ANSWER: Not a lot to go on here. Won't shift what? Into gear? Gears while driving? Into 4WD?

---------- FOLLOW-UP ----------

QUESTION: Won't shift out of park, with the truck running & the brake pedal pushed in.

Answer
Thank you for following up and clarifying the question. Your problem is with the Brake Transmission Shifter Interlock assembly on the transmission cable. To unlock the shifter the brake pedal sends a signal to the Instrument Cluster that the brake pedal has been pressed then the Cluster sends 12v down to the Interlock unlocking the cable. Either the cluster is not sending the needed voltage or the Interlock itself has failed. An easy test would be to apply 12v to the interlock at the Dark Blue/Yellow wire at the interlock solenoid. If that unlocks the shifter then you'll be able to drive the truck but it indicates that there is a problem with the cluster or the signal from the brake switch. If it does not unlock the shifter then the cable and interlock will need replacement.