Brake light came on, no reason

[Warrennc]

Ok. Parked the truck. Went into a store. came back out. Started the engine.
Released the brake and the brake light on the dash did not go off.
Checked the brake fluid. Was full.
Checked to see if the brake released or not. It released.
Anyone have any idea what the most common cause of that would be?
Considered the brake peddle not lifting all the way. It feels like it is all the way up.
Wire harness at the master cylinder look good. Were replaced along with the master cylinder not to long ago, Previous owner fix.
Truck does not pull one way or the other and hubs not getting hot so I presume the brakes are not stuck.

Haven't had the time to check the switch at the peddle to see if it is busted. Assuming it is at the peddle.
Oh, almost forgot. The ABS light is on most of the time. Would that effect the brake light on the dash?
Thanks.

[ZMANN]

the switch at the pedal is the likely culprit

the abs light has no impact ,, that's going to be a faulty ABS sender

[Warrennc]

Thanks. Will reach up in there and see what I find. Wiggle a few wires etc and see if that makes a difference. :

Do you know if the switch is closed when the peddle is up (brakes engaged) or down (disengaged)?

[Patrick Feeley]

Low vacuum can also cause the dash brake light to illuminate (as well as the aforementioned parking brake and low fluid). Parking brake switch will close with the parking brake engaged. Cheers!

[Warrennc]

Most switches brake and will not close. Thus the light should not come on if the switch is busted...maybe.
So, Moving on to the next mentioned possibility.....
Assuming I have low vacuum pressure. What other symptoms should I look for that may indicate a low vacuum pressure?

Thanks.

[TRAXN]

A simple check for the parking brake signal switch would be to unplug the single wire going to the switch. That wire is "looking" for a ground to illuminate the light on the dash. That will rule out that problem

[Warrennc]

Thanks, will definetly give that a try.

[ol_Blue97]

had this happen to me once, i blew the fuse for the brake lights... check to see when you press the peddle if the lights even come on. but i think it was flashing at me, not sure

[Warrennc]

Worth a look. But knowing my luck, it won't be that easy.

Thanks. Crossin my fingers that is it. Will check it in the AM.

[Warrennc]

Brake lights working just fine. So, that aint it.
Will be checking the switch when I get some time, Probably this weekend.

Anyone have any ideas what symptoms would occur with low or no vacuum?
Just so I can compare to what it is doing now. Crossin my finners that it aint the vacuum system.