The "service brake system" is a problem with the 2005GMC Yukon.

The brake light indicator is on the hood of your car to let you know there is an issue.The anti-lock brake system has its own warning light.There is a problem with the physical brakes.

The emergency brake is the first thing you should check if you are reading this article.The brake light will stay on if it is engaged.The brake warning light will stay on if the handle is not all of the way down.Check to make sure that the brake light is turned off.

If the emergency brake didn't fix the situation, it's time to look into what is causing the brake warning light to stay on.The brake light is the most important warning light.We don't recommend driving with this light on.When the brakes fail, doing so may lead to injury.

The brake warning light indicates that one of the major brake components has failed, typically detected through a loss of pressure.You will feel a loss of pressure in the form of a brake pedal.

If the brake light only comes on when you push the brakes, that is a sign that the pressure in the system is too low.Either there is a leak or the brakes need bled.

Since you have already checked the emergency brake handle, it is time to check the master cylinder.Adding more may provide a temporary fix if it is low but not empty.

If the brake fluid appears to be all the way out, you need to add more, bleed the brakes, and fix the problem so that you don't repeat it again.Poor brake performance is caused by leaking brake fluid over the pads and shoes.

Adding fluid without fixing the problem is just a temporary solution.Over time, the leak can lead to brake failure.