Questions and Answers

Ford Explorer Dash Brake Light Q. I have a 1992 Ford Explorer. The red Brake Light on the dashboard comes on whenever the brakes are pressed quickly. I was thinking the proportioning valve, but I tried the following tests. With the car running and stopped (in Park) I press the brakes quickly, the light does not come on. Driving in reverse about five mph and step on the brakes the light does not come on. Driving forward about five mph and step on the brakes the light comes on.

This sounds like a short or loose connection of some kind. Do you agree? The car does have about 150,000 miles on it. The brakes feel fine and stop fine.

Thanks for any help,
Robert

A. The Brake Proportioning/Combination Valve consists primarily of a pressure differential valve, brake lamp warning switch and a proportioning valve. A pressure differential shuttle and/or metering valve are also incorporated with some valve applications.

The metering valve delays front disc brake effectiveness until the rear brake shoes contact the brake drums. The proportioning valve regulates rear hydraulic system pressure to prevent rear brake lock-up. The pressure differential valve senses hydraulic system pressure and will activate the brake lamp warning switch if a pressure loss occurs. The pressure differential shuttle bypass feature provides full rear brake application if front hydraulic system pressure is significantly reduced

A short circuit is a possibility, but it would be low on my list. What I would do first is to check the brake fluid level and sensor. Then the parking brake switch would be the next thing to eliminate.

Then try bleeding the brakes. The light will come on if there is unequal pressure between the two halves of the brake system. Bleeding the brakes will equalize the pressure and the light will no longer come on.