My friend has a 97 S-10 v6 and the first thing we did was do a headlight converion w/ h4 bulbs. That was more than a year ago. About two months ago I rewired his bumper blinkers so that the brighter filament lights up when he turns on his headligts. It looks real sweet. But just recently the left corner doesn't light up when you turn on the lights. Only when you turn on the bilnker. what should I do or check. Everything else works fine.