Recirculating diodes help to contain inductive load transients that occur when a solenoid coil is turned off (e.g. Model 812 solenoid valve) or a motor brush breaks contact with its armature winding (e.g. SafeSet Parking Brake). They operate below TVS thresholds, keeping transients to a minimum. Recirculating diodes are however, polarity sensitive, and will blow if wired backwards, ceasing to perform their intended function, often without any indication of failure