Possible Causes
WARNING: This page is about a different car, the 2002 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
DTC 73/B0135 could be caused by a short between Yellow/Black (circuit PL+) and Yellow (circuit PL-) wires in driver-side seat belt pretensioner squib circuit, driver-side seat belt pretensioner squib malfunction or air bag sensor assembly malfunction.
NOTE:
During testing, if DTCs other than DTC 73/B0135 are displayed, disregard them.