Looking for help connecting a simplex 4010 to a simplex 4003

My son and I are attempting to connect a 4010 to a 4003. We have successfully used the 4010, but we are uncertain about the connections for the 4003. We have connected power to the 4003, and it lights up when power is applied. However, we are particularly unsure about connecting a wire from the 4003 0v to the 4010 auxiliary power negative.

TIA
-Curt