A medical device system for determining pacing threshold data, comprising: a cardiac capture sensor; a phrenic nerve stimulation sensor; a pulse generator selectively coupled to a plurality of electrode vectors; a processor coupled to the cardiac capture sensor, the phrenic nerve stimulation sensor and the pulse generator; and the processor being configured to determine a cardiac capture threshold from the cardiac capture sensor signal while detecting phrenic nerve stimulation from the phrenic nerve stimulation sensor signal for each of the plurality of pacing electrode vectors, characterized in that the processor is programmed to perform the determining by: controlling the pulse generator to deliver a stimulation pulse via a selected one of the plurality of pacing electrode vectors using a first pacing pulse output; detecting from the phrenic nerve stimulation sensor signal whether phrenic nerve stimulation occurs in response to the first pacing pulse output; adjusting the stimulation pulse by a first step to a second pacing pulse output in response to detecting the phrenic nerve stimulation; detecting from the cardiac capture sensor signal whether cardiac capture occurs in response to the second pacing pulse output; and adjusting the stimulation pulse output by a second step to a third pacing pulse output in response to detecting cardiac capture, the second step being less than the first step. a cardiac capture sensor; a phrenic nerve stimulation sensor; a pulse generator selectively coupled to a plurality of electrode vectors; a processor coupled to the cardiac capture sensor, the phrenic nerve stimulation sensor and the pulse generator; and the processor being configured to determine a cardiac capture threshold from the cardiac capture sensor signal while detecting phrenic nerve stimulation from the phrenic nerve stimulation sensor signal for each of the plurality of pacing electrode vectors, characterized in that the processor is programmed to perform the determining by: controlling the pulse generator to deliver a stimulation pulse via a selected one of the plurality of pacing electrode vectors using a first pacing pulse output; detecting from the phrenic nerve stimulation sensor signal whether phrenic nerve stimulation occurs in response to the first pacing pulse output; adjusting the stimulation pulse by a first step to a second pacing pulse output in response to detecting the phrenic nerve stimulation; detecting from the cardiac capture sensor signal whether cardiac capture occurs in response to the second pacing pulse output; and adjusting the stimulation pulse output by a second step to a third pacing pulse output in response to detecting cardiac capture, the second step being less than the first step. controlling the pulse generator to deliver a stimulation pulse via a selected one of the plurality of pacing electrode vectors using a first pacing pulse output; detecting from the phrenic nerve stimulation sensor signal whether phrenic nerve stimulation occurs in response to the first pacing pulse output; adjusting the stimulation pulse by a first step to a second pacing pulse output in response to detecting the phrenic nerve stimulation; detecting from the cardiac capture sensor signal whether cardiac capture occurs in response to the second pacing pulse output; and adjusting the stimulation pulse output by a second step to a third pacing pulse output in response to detecting cardiac capture, the second step being less than the first step.