The ADS131B04-Q1 features an internal analog test signal that is useful for troubleshooting and diagnosis. A positive or negative dc test signal can be applied to the channel inputs through the input multiplexer. The multiplexer is controlled through the MUXn[1:0] bits in the CHn_CFG register. The test signals are created by internally dividing the reference voltage. The same signal is shared by all channels.

The test signal is nominally 2 / 15 × V_REF. The test signal automatically adjusts its voltage level with the gain setting such that the ADC always measures a signal that is 2 / 15 × V_{Diff Max}. For example, at a gain of 1, this voltage equates to 160 mV. At a gain of 2, this voltage is 80 mV.