Issue with brakes
 

I have a 1999 E150 Conversion Van. Not too long ago, the emergency brake light came on(and has remained on) and the brake pedal does not have much resistance when I press it. I don't mind getting my hands dirty, but I don't know where to start to diagnose this. Any help would be appreciated.

Most vehicles came out with what is referred to as a split system. One wheel from each side was controlled by one part of the system while the other remaining wheels were controlled by the other half. The design was to provide as close to equal braking if one part of the system failed. The soft pedal was one of the symptoms of a failure in the system. When this took place the system with the lower pressure allowed a centered valve to shift toward the side with the lower pressure, (leak~).
There is an electrical contact on that valve to notify the operator of the problem when the valve shifted due to difference in pressures. That's when the red light came on.
If that was the problem,however, the light also could come on with a low fluid level in the master cylinder.
If you are not sure how to check the system , it is best to have someone that is familiar with brake systems check it out since we don't get too many chances to make up for a poor stop.

Thanks Hanky.
The brake fluid level doesn't appear to be low. I can't be positive. It looks like it has 2 sides. The right side where you pour in the fluid is low. The other side(left) with the MAX side is dark. I can't tell if it is dark because of the fluid in it. It that's the case, then the fluid is to the MAX line. Could air in the lines be causing my problem?

Air does not usually get into the lines except for if someone opened the system to do some work and allowed air to replace the fluid , or , if there is/was a leak and the master cyl ran low where air now was pushed into the system and fluid was added without bleeding the air out of the lines and components.

Great info. Agree with you !!