A display may have a substrate layer to which a display driver integrated circuit and flexible printed circuit are bonded. The display driver integrated circuit may be provided with switches and control circuitry for controlling the operation of the switches during bond resistance measurements. Test equipment may apply currents to pads in the display driver integrated circuit through contacts in the flexible printed circuit while controlling the switching circuitry. Based on these measurements and the measurement of trace resistances in a dummy flexible printed circuit, the test equipment may determine bond resistances for bonds between the display driver integrated circuit and the display substrate and between the flexible printed circuit and the display substrate. Displays may have master and slave display driver integrated circuits that share coarse reference voltages produced by the master from raw power supply voltages.