My 1991 f250 brake warning light glows very dim during normal driving. Its bright with the parking brake engaged. The brakes seem to work fine exept the greasy left rear (see earlier post). My popular mechanics cd does not tell me anything about the function of the light. Any info would be helpfull.

 

Hi my name is Bret and I too own a 91 F-250.
I have a Chilton's manual for 87-96 full size ford trucks,the only thing it really covers well is the brake system.
If you go to a checker auto, look for this book, it's gray with a red ford truck in the center, open it to chapter 9, this is the brake section.
Hope this helps. if not let us know.

BRET

 

The brake warning light staying on could indicate,that possibly the Emergency brake switch is not working propperly,the brake fluid resorvoir is low or not working propperly,or if it is a diesel it can mean low vacume.One of the indicator switches may have a slight short or may not be completely actuating.Those type of problems are like chasing a ghost.Good luck
Jeff,
super@sierratel.com

 

This could be one of three things:
- you really do have a brake problem

- you need to replace the 'rabs' valve

- you need to replace the control assembly
brake proportioning system under the dash