Venture Van taillight mystery

I have a 1998 venture van and I am experiencing some strange taillight behavior. When i step on the brake and turn on the right side blinker, the blinkers are very rapid. However, the left side is not. If the headlights are on, the indicator on the dash show both lights illuminating. I have seen the lights at night and all of the lights on the right side(marker, signal, brake light, reverse light) are dim. Not to mention, the right side blinks so rapidly that it almost seems that they aren’t doing a thing. Help!!! Thanks.

I suspect a bad ground.

how do I check for this? any suggestions?

The bad ground is likely and should be checked, but you can try replacing the right side rear lamp.

The problem may be as simple as a dual filament bulb where the filament for the turning signals is sagging and making contact with the other filament. I would start by changing both the right rear bulb as suggested ealier and the right front bulb as it probably has the other filament that is used for the parking lights.

If this doesn’t solve the problem, then have a shop look for a defective ground.