Help! Brakes suddenly go out and I frantically pump them and car accelerates for a second. dude am I CURSED

[Fredzeller]

shoot. I just bought a 97 Explorer Limited 5.0 V-8 with 97k miles, one owner (honest dude), great condition about 2 months ago....

I started truck up today and went down street to a stop sign, Brakes didn't work suddenly. I pumped them and the truck actually accelerated for a quick moment. The brakes worked a moment after that, thank god. (There were pedestrians around). It was a total... honestly... total time of about 2 seconds, but that can be dangerous.

Does anyone know what the problem is? I am not mechanically inclined at all.

ok i know this sounds crazy but... My last car was a 2000 Honda Passport (Isuzu Rodeo) and THE SAME THING HAPPENED like once every few weeks for about 2 months. Had it checked out by 3 places, no luck. Never figured it out even after lots of internet research. 2 other people in my house used it and it happened to them as well. The car's second transmission eventually went out in December 2019, flew carless for a year, and then bought this Explorer.

its happening again, man. im cursed! gotta do better karma wise . Any help appreciated.
Thanks Fred

 

[drakon543]

off hand maybe the brake booster is going bad. typical has a vacuum line going to the brake booster. if the brake booster is leaking i suppose it could allow the engine to pull in a small shot of air through the brake booster. would be like a quick blip of the throttle until the booster diaphragm reseals.

 

[Fredzeller]

off hand maybe the brake booster is going bad. typical has a vacuum line going to the brake booster. if the brake booster is leaking i suppose it could allow the engine to pull in a small shot of air through the brake booster. would be like a quick blip of the throttle until the booster diaphragm reseals.

thank you! we also remembered there was a loud sound like a gear having trouble turning, very low bass sounding "grrrr" for about a second before the brakes went out. Want to be detailed in case it helps others.

 

[drakon543]

a grrr sound doesn't help much but relating to certain vehicles ive had in the past ive accompanied a similar sound to an overactive abs system. if the abs believes your brakes are locking up even with a light pedal touch it will cut back and or pulsate your braking pressure. wheel speed sensors are generally at fault there but they are usually accompanied by abs warning lights. a wheel speed sensor that's bad enough to really mess with your braking will generally trigger a warning light pretty quickly. it wont cause any momentary acceleration however just terrible brakes.

 

[XLTrunner]

I was kind of thinking along the same lines of the ABS acting up. Don't imagine someone in L.A. has much (if any) experience with ABS engaging what with no slick winter roads to deal with. Can't explain the brief acceleration, though.

 

[Mbrooks420]

Is your brake or abs light on?

 

[fast_dave]

@Fredzeller

Start easy and for $0.00

Perform a Brake Booster Test

With the engine OFF, pump the brakes 3 or 4 times to remove any vacuum left in the booster.

Then, with your foot on the brake, press down until the pedal stops, keep your foot on the brake pedal, and start the engine.

If the brake booster is working, your foot should drop ANOTHER 1/4 to 1/2 inch.

If your foot doesn't drop, the brake booster in the problem.

Hope that helps -

 

[mic98xlt]

a grrr sound doesn't help much but relating to certain vehicles ive had in the past ive accompanied a similar sound to an overactive abs system. if the abs believes your brakes are locking up even with a light pedal touch it will cut back and or pulsate your braking pressure. wheel speed sensors are generally at fault there but they are usually accompanied by abs warning lights. a wheel speed sensor that's bad enough to really mess with your braking will generally trigger a warning light pretty quickly. it wont cause any momentary acceleration however just terrible brakes.

I had the same problem as OP coming to a stop sign on a deep grade. I too had the sensation that my '98 Explorer sped up instead of stopping, and somewhat a growling sound and plus pulling to one side. After chasing it for over a month, it was the wheel sensor that falsely reported to the ABS that one front wheel was locking causing the ABS to full release the brakes completely momentarily. The way I confirmed it after thinking it was a hardware problem (caliper, brake pads and etc.) was to pull the fuse for the ABS motor. This divorced the ABS from the system and showed the vehicle would stop perfectly without pulling to one side, and no acceleration sensation. I never got an ABS light but the wheel speed sensor was definitively bad. I agree with drakon553.

 

[RickOTR]

That was the ABS Module motor activating. Could be the sensor, but it sounds like the module could be going bad. Might want to have a professional look at it.

 

[96eb96]

I'll suggest forscan. It may have the ability to read live ABS pids (ability may vary by year). Then you can graph each wheel speed sensor as you come to a stop. That is exactly what they do in a shop. The rear diff abs sensor often goes bad, it is real cheap to replace and may be the issue.

 

[Brem95]

I know this sounds dumb but make sure you’re not accidentally pushing both pedals at once. I’ve had the exact same thing happen a few times. Doesn’t help when I have size 14 feet and if I’m wearing steel toe boots...

 

[J_C]

Brake momentary failure when coming to a stop is a classic sign of the beginnings of an ABS sensor failure. Could be sensor alone, or wiring/connector to it, or could be the hub is failing, or on the rear sensor, after this long it could need some gunk cleaned off.

Hook up a scan tool capable of showing the abs sensor data. Forscan with an OBDII ELM327 dongle is one of the cheapest ways to do that if you don't have such a tool. The basic tool they use for free at Autozone/etc won't do that, unless they've upgraded their scan tools in recent years and I didn't notice.

 

[GT2000]

Yes could be ABS, I had a similar scare with my 03 Grand Am a few weeks back, it has ABS issues with the wheel speed sensor, light comes on every once in awhile when you make a tight turn. Anyway, in the driveway turned to park and hit brakes and felt abs push back for a second, then it stopped and the warning light popped on. If it had pushed back on the pedal for a few more seconds i'd had been through the garage door.

 

[Scotts96sploder]

I know this sounds dumb but make sure you’re not accidentally pushing both pedals at once. I’ve had the exact same thing happen a few times. Doesn’t help when I have size 14 feet and if I’m wearing steel toe boots...

Might be onto something here. Depending on the automatic vehicle, some I two step and some get the right foot depending on the pedal setup. My x gets both feet because the pedals are close together. I could probably brake stand the thing with one foot, and I only wear a size 10.

 

[Fredzeller]

Is your brake or abs light on?

No the ABS light is not on, but i remember it going on and off randomly with my 2000 passport