Rear side markers issue

[John B.]

I have noticed on my new/old 73 vette that the emergency flashers are blinking really fast. Quick diagnostic showed the rear side markers, (both), are not blinking. Also they don’t blink with turn signals on. All other lights work as they should. The side markers are on with parking lights on so there is power and ground. Anyone had/seen this issue before that would help cut my diagnostic time down.

[Terry M.]

I have noticed on my new/old 73 vette that the emergency flashers are blinking really fast. Quick diagnostic showed the rear side markers, (both), are not blinking. Also they don’t blink with turn signals on. All other lights work as they should. The side markers are on with parking lights on so there is power and ground. Anyone had/seen this issue before that would help cut my diagnostic time down.

You actually do have a ground problem. Your situation is known as a "high resistance ground." This means that the side markers work fine with the parking lights because the amount of current going to ground for just the side marker lights is small, but when the amount of current needed for the hazard signals and the side markers is added together the ground can't handle all of it. The problematic ground is at the frame by the rear lights. Check it and clean it well.

[Steven B.]

You actually do have a ground problem. Your situation is known as a "high resistance ground." This means that the side markers work fine with the parking lights because the amount of current going to ground for just the side marker lights is small, but when the amount of current needed for the hazard signals and the side markers is added together the ground can't handle all of it. The problematic ground is at the frame by the rear lights. Check it and clean it well.

I had such a problem with mine years ago and it was as Terry stated. My loose ground was at the rear also.

[John B.]

Thanks so much. I figured it to be a possible ground and since the rear tail lights flashed I knew I had a signal from the flasher unit. Knowing where the ground is located will help so much.

[Mark E.]

The rear side marker lights are not supposed to blink.