Brown the ground turkey and onions on the saute setting of a slow cooker or in a skillet. Season with salt and pepper to taste.
If needed, transfer the browned turkey and onions to a large slow cooker or a stockpot.
Drain the corn and olives. Do not drain the rest of the cans. Add the beans, corn (drained), tomatoes, green chiles, olives, taco seasoning, and ranch dressing mix.
Cook in a slow cooker on low for 6 to 8 hours or simmer over low heat for about 1 hour in a pot on the stove.
To serve, ladle soup into bowls. Top with corn or tortilla chips, sour cream, cheese, green onions and/or jalapenos.
