The present invention relates to an implantable stimulator device, comprising a plurality of electrodes, at least one first current source configured to produce at least one current, a first plurality of switches coupled to the at least one first current source, wherein the first plurality of switches are selectable to distribute the at least one current to one or more of the electrodes, a second plurality of switches, wherein the second plurality of switches are selectable to distribute the at least one current from one or more of the electrodes, and monitoring circuitry configured to measure at least one first voltage, each at least one first voltage comprising a voltage only across one of the first switches, and at least one second voltage, each at least one second voltage comprising a voltage only across one of the second switches, and wherein the monitoring circuitry is further configured to determine whether a failure condition has occurred by assessing the at least one first voltage and the at least one second voltage.
