Relay and Headlights

My factory headlights are being ran through a relay harness in which the relays are triggered by one side of the factory headlight wiring.
This leaves me with an unused factory connector.

My question is about this unused factory connector.

Is it suitable to wire this unused side as the trigger for an auxiliary light system? The auxiliary circuit will go from factory connector, to auxiliary switch, to relay. The auxiliary lights will be able to be switched on/off but only while primary headlights are being used. Both primary and auxiliary will run standard wattage bulbs.

Thank you.

Probably, but what kind of auxiliary lights, and what kind of vehicle?

98 GMC Suburban factory lighting is 9006/9005 Philips Vision Plus.
The auxiliary will be Grote 5.75 inch lamp buckets with H4 Osram 70/65 bulbs.

Wiring is 14 ga trigger wiring and 12 ga for the other contacts ran through Tyco 20/30 amp relays.
15 amp fuses at the relays battery connects and also between the factory headlight connector and auxiliary on/off switch.

That's a really simple, conventional headlamp circuit, so you shouldn't have any problem triggering the aux H4 high and low beams the way you describe. But be careful if you have modified the truck so the low beams stay on with the high beams; you don't want high and low on together in an H4 (or any other 2-filament bulb).

Very good. I did not make my primary lighting harness, but with the crimper you recommended...and a bit of practive, I am putting together a sturdy harness. With the good parts I've learned about, this seems to be turning into an enjoyable project.

High and low will be seperate and not capable of being on at same time.

Thank you for the input! Hey, it seems I've learned from this forum.