1st check your battery. kung may tester ka, check mo ano voltage. Should be at least 12.4 volts with engine off and 13.8 to 14.4 volts when idling. While your at it clean your battery terminals and tighten them.

2nd check your ground. You should have at least 2 ground points. Battery - to chasis and engine to chasis. A loose ground can cause all sorts of probs. Had a loose battery to chasis ground in my car. Results were dim lights. Kumukurap kurap pa ang headlights ko. Eventually car started to run rough. Tester showed fluctuating voltage. Tightened the ground bolt and it solved all 3 probs.