Hi RedRunner2015,
Here's a way to implement your relay 'trigger' from the headlight wiring source w/o cutting into the oem headlight harness. Cutting directly into the oem headlight wiring harness may cause damage, or compromise the small gauge (H-11) leads in that exterior lighting loom. Using an aftermarket 'pigtail' extension will prevent the risk of that from ever happening. Here's a link to the part:
H11 Extension Wiring Harness Socket Headlight Connector Adapter for Car - Walmart.com Rgds
