An implantable cochlear stimulator (ICS) has eight output stages (212), each having a programmable current source (212B) connected to a pair of electrodes, designated "A" and "B", through respective output coupling capacitors and an electrode switching matrix (212C). An indifferent electrode is connected to each output stage by way of an indifferent electrode switch (212D). An output mode register (208) controls the switching matrix of each stage, as well as the indifferent electrode switch, to configure the electrodes for: (1) bipolar stimulation (current flow between the pair of electrodes of the output stage), (2) monopolar A stimulation (current flow between the "A" electrode of the output stage and the indifferent electrode), (3) monopolar B stimulation (current flow between the "B" electrode of the output stage and the indifferent electrode), or (4) multipolar stimulation (current flow between the "A" or "B" electrode of one output stage and the "A" or "B" electrode of another output stage). The mode register is set by way of a command word, transmitted to the ICS from an external wearable system (10) as part of a data frame. The voltage at the "A" and "B" electrode of each output stage may be selectively telemetered to the wearable system, as may the current flow through the indifferent electrode, thereby facilitating a measurement of the electrode impedance. The "A" and "B" electrodes of each output stage may be selectively shorted through a high or low resistance in order to discharge the output coupling capacitors.