ABS light coming up when I turn on the lights.
 

After about 2 seconds when I turn on the lights (parking lights or headlights) the ABS light comes up. The ABS light is going off as soon as I turn on the lights. Thinking it might be the droppage of voltage I checked the voltage at the battery. The voltmeter is reading 13.30 volts. I checked the OVP relay's outputs. There is 13.30 volts coming out of OVP outputs(87E,87l) when the ABS light is on.
I am suspecting the front passenger side parking light because there is no current coming to it. It might have shorted with some wire causing the ABS light to come up. I also remember my mechanic grounding the passenger side headlights because the grounding was bad and the headlights were glowing dim. However, this was 2 weeks ago and ABS light thing happened just yesterday.
Please somebody help me out with this. I apologize for asking the forum my stupid questions. There is something going wrong in my car.

The ground for the ABS computer( & over-voltage relay) is on the rt shock tower. The ground for the ABS hydraulic pump is a very large braided wire just beneath the pump. Check them closely.
Does the ABS lamp come when you switch the rear window defogger on?? IF so then you need to check the charging system again.