94 jeep grand Cherokee. When I turn on the headlights while stopped at a light, I get really low voltage drops to the point the abs light comes on the radio shuts off. Turn signal excerbates the problem. I had a problem with the turn signal relay but with a few taps it started working and hasn't acted up in a few weeks. The right fender turn bulb looked like it was blown out so I thought that might be part of the problem. I pulled it and took voltage readings. 14v from positive battery to one side of the plug and .56 volts to the other? Maybe I'm wrong but that doesn't seem normal. Curious before I tear things apart if there's some obvious place I should look. This was just with the parking lights on. This jeep has the alternating turn signals.

 

Okay, here's where it gets confusing. The side marker lights are wired thru the turn signal bulb filaments as ground. With the headlights on, they are supplied with 12v thru the running light/ tail light circuit, but ground thru the turn signal bulb. When you turn the signal on, 12v is supplied to both sides of the marker light and they go out. As the turn signal flashes, the side marker will light alternately. Being wired in series with the turn signal bulb, the signal bulb's filament is too big to light when the side marker is powered up.

It sounds like you have a major ground fault connection somewhere.

 

That's what I figured. I just wanted to see if I may have missed something stupid before I go tearing everything apart.

 

Grounds. See my sig, #1.