Originally Posted by Tech II

So you pulled the low beam relay, and you have power on two terminals?

If yes, insert relay, and have someone manually turn the low beams on....with your hand on the low beam relay, it should click...if it doesn't then the BCM is not grounding the relay.....

You would need a wiring diagram of the BCM, to see if you are getting a signal from the headlight switch(all the switch does is give a ground input to the BCM) and a ground signal from the BCM to the relay......

Good way to check the relay and light circuit is this.....you have 4 terminals(terminals are numbered on the bottom of the relay)....85 is bat to coil of relay....30 is bat to the switch of relay...86 is from the BCM(when BCM grounds this line, relay is turned on)......87 is the output of the relay switch to the fuses.......quick check is wrap a paper clip around terminal 86, have end of clip stick outside the relay...insert relay......now just take a ground and touch the end of the clip....low beams should come on.....this verifies the circuit........so the problem is either no output from the BCM, or no input to the BCM from the headlight switch....