Bad brakes

Twice in the last two or three weeks my brakes have suddenly went hard as a rock and wouldn’t brake (luckily I was just idling along both times). They’ll go stiff and I’ll hear a grinding noise. I’ll press as hard as I can and they’ll release and brake fine. What could that be? I’m pretty car savvy and know how a brake system works but I’m stumped.

Sounds like maybe the ABS is malfunctioning.

Assuming, of course, that your F150 is new enough to have ABS. You didn’t tell us the year of your truck.

It’s a 1997 2WD with ABS but I really don’t think thats what it is cause the ABS light doesn’t come on but… At first I was thinking that one of my rotors was cracked and a pad was jamming…hence the grinding noise and it only happening when I’m pulling up or backing up. I do know I need to replace the rotors cause it vibrates when I brake but I haven’t actually looked at them yet.

Well, it’s probably not the ABS, but I think it’s time for a good, hard look at the brakes. Don’t put this off. It could be dangerous.

In my troubleshooting I see a lot of people saying hard brakes could be the booster. What stumps me though is the grinding…what the hell is that? I’ve only had the truck for about a month and it sat for a long time before that so it needs a bit of TLC. I actually took a Brakes and Chassis class in college and I am dumbfounded as to what this could be. I guess I will just have to R&R everything. Problem is…I won’t know if its fixed cause it just suddenly happens then goes away not to happen for another week or so. Thank you.

The booster was my first thought also, but since it’s also interfering with your ability to brake I suspect the ABS system. A failed booster will make the pedal hard and braking reqiure more force, but it won’t disable the brakes entirely.

Even though you have no ABS light, I’d still pursue this and have it looked at ASAP. Unfortunately intermittant problems that don’t store codes can be tough to diagnose, but this one’s important enough to pursue.