Strange braking issue today... hoping it's not my booster/ABS pump?

[pudzley]

Hey guys - I picked up a 2004 4WD SR5 with 96k miles last month and noticed an odd issue today when braking. I was backing out of a parking spot and let go of the gas so the car would roll back and then when I applied the brakes, it almost felt like I had no brakes and there was a weird almost like scraping sound. The truck did stop and I immediately heard a hum behind the dash (I'm guessing electric brake booster pump or something). Since then, brakes have been fine but I'm concerned about what this was. Does it sound familiar at all? I tried searching but didn't come up with anything. I noticed since day 1 that if I put the key in the ignition but don't start the truck, I heard that hum for a few seconds, then it stops and then it does it again shortly after, etc. I actually thought this was the fuel pump priming at first but now I'm thinking maybe it's related? Any help is appreciated.

 

[radlynx]

Hey guys - I picked up a 2004 4WD SR5 with 96k miles last month and noticed an odd issue today when braking. I was backing out of a parking spot and let go of the gas so the car would roll back and then when I applied the brakes, it almost felt like I had no brakes and there was a weird almost like scraping sound. The truck did stop and I immediately heard a hum behind the dash (I'm guessing electric brake booster pump or something). Since then, brakes have been fine but I'm concerned about what this was. Does it sound familiar at all? I tried searching but didn't come up with anything. I noticed since day 1 that if I put the key in the ignition but don't start the truck, I heard that hum for a few seconds, then it stops and then it does it again shortly after, etc. I actually thought this was the fuel pump priming at first but now I'm thinking maybe it's related? Any help is appreciated.

yes thats your brake booster pump.

Sent from my SM-G930T using Tapatalk

 

[pudzley]

yes thats your brake booster pump.

Sent from my SM-G930T using Tapatalk

Thanks. I just did a bunch of reading on this and found out these have an electric booster pump and an abs pump. Is it normal for the booster pump to operate for a few seconds every few stops or so? Is there a way for me to test if these components are OK? I read how much it costs to have these replaced and I'm really hoping that's not on the horizon for me. But this episode with backing out of the parking spot today was really odd. I don't want to take any chances with brakes. No lights on the dash...

 

[AuSeeker]

Thanks. I just did a bunch of reading on this and found out these have an electric booster pump and an abs pump. Is it normal for the booster pump to operate for a few seconds every few stops or so? Is there a way for me to test if these components are OK? I read how much it costs to have these replaced and I'm really hoping that's not on the horizon for me. But this episode with backing out of the parking spot today was really odd. I don't want to take any chances with brakes. No lights on the dash...

Yes it's normal, the booster pump will come on for approximately 20 seoconds when you first start the 4R and then again about every third depression of the brake pedal to maintain the hydraulic assist pressure of the brake system.

The small electric motor which is what you're hearing sometimes fails after many years, this is the most common failure and can be replaced without replacing the entire assembly.

My 4R is 14 years old and the electric motor is still working fine and as it should, you shouldn't have any worries with your master cylinder it sounds like it working as it should.

 

[Seymore Butts]

when I applied the brakes, it almost felt like I had no brakes and there was a weird almost like scraping sound.

I'd start by checking for a completely worn out brake pad and a scored rotor.