Code 37 is improper voltage level in the side airbag on the passenger side. This could be caused by a short to ground or, more likely, a high resistance connection between the restraints control module and the PS side airbag assembly.
Even if your truck doesn't have the optional side airbags, it still has the wiring for them and uses a yellow resistor cap to simulate the side airbag. Same story - probably a poor connection at the RCM or at the resistor cap under the passenger seat. Working on the SRS can be very hazardous so unless you are comfortable working on this system, take it to a professional for repair.
Clay