What is the exclamation dash light on a 2004 mercury monterey minivan?

The exclamation dash light on a 2004 Mercury Monterey minivan is the Brake System Warning Light. This light comes on when the fluid in the brake master cylinder is low, or if there is a problem with the brake system. If this light comes on, it is important to stop driving and check the brake fluid level immediately. If the brake fluid level is low, you can usually just add brake fluid to the master cylinder. However, if the brake system warning light stays on after adding brake fluid, it is important to have the brake system checked by a qualified mechanic.