Ok. Issue: Brake light in the dash is on. Came on yesterday right after I voted. Guess the truck wasn't happy with my choice. . But I digress.

Haven't had the time to really diagnose the reason yet.
But, from what little I know. There may be 3 causes. Low brake fluid (Checked that and it is fine) or possibly a failure in the sensor and/or wiring there. Peddle not hitting the switch when parking brake is not engaged (or a busted switch or peddle not hitting the switch anymore due to switch busted or moved) and someone mentioned, low vacuum.

I will try to get some time this weekend to check the switch.

I would presume with low vacuum, there would be other symptoms that would point to that.
Would love to see a list of symptoms of low or no vacuum.

Thanks.

 

Another symptom would be stiff brake pedal...

Make sure the little wire that goes into the top of the ebrake assembly is in it's place... Otherwise that will bring on the light.

 

Thanks. Very helpful.
Ahh. so that is the vacuum boost brake master cylinder there. Big drum between master cylinder and the firewall.
Brakes are not stiff. if I step on the brake to hard by accident I have to scrape my face off the windshield.



Exaggeration of course but, they work quite well.
They work better than on my old suburban that I traded for this truck.
The truck stops faster than any other vehicle I have ever had. And so far, I have not had the need to lock it up. ABS not working so, gotta be careful there. My old suburban didn't have ABS installed so. kind of use to it by now.

Sounds like it most likely is the switch or wires to the switch.
Will be looking into the switch and wire position very closely this weekend.

Any other symptoms that are a dead giveaway on a possible vacuum issue?

Thanks.

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Ok, another forum gave me additional symptoms of low vac. My truck is not exhibiting any of those symptoms so. Yup, gotta be switch or wire.

 

Ok, Mechanic confirms, Not an issue with the Vac system.
The issue is. The sensor at the bottom of the brake fluid tank went bad. Unplug the sensor and the light goes off. May just leave it unplugged for now and just keep an eye on the fluid level.