The thing about doing this is when you use your howler, the coyotes could very well not answer BUT yet be on their way. So, if you're driving around and stopping every now and then and howling, waiting for a vocal response and hear none and leave, you very well may be missing out on action! It is well known that coyotes won't always answer a howl, and often times will come to it silently!!
Back to the question, you can use a white light, BUT try to avoid shining it directly at the target. And since you're new at night calling, you really need to know or identify your target. In other words, critters that aren't your intended target may respond to your call, so you need to make absolutely positve ID on a critter before pulling the trigger!