87 & 88 headlight module

Is there any way to check the headlight module used on 87s & 88s with a DVOM? Mine had no ground output, got one from a junk yard, plugged it in and it was the same. Input ground and all input wires check good at 5 wire connector. The module(s) switches the + side at the output terminals, but no ground circuit through the module. Anyone with a factory manual that can check? Thanks.