2001 4Runner ABS Issue

[ToyotaBrah]

Hi all,

I have recently purchased a 4Runner from Seattle, WA. It has 200K and runs great, with the exception of a few minor issues.

One issue that has me stumped is the ABS system. Intermittently, the ABS system will prime itself when I apply the brakes. I have cleaned all 4 wheel speed sensors (the rears were really dirty), crossing my fingers that would solve the issues, but the problem still persists.

Where does one go from here? ABS modulator perhaps at fault?

Thanks for your input.

 

[BlackCat914]

Hi all,

I have recently purchased a 4Runner from Seattle, WA. It has 200K and runs great, with the exception of a few minor issues.

One issue that has me stumped is the ABS system. Intermittently, the ABS system will prime itself when I apply the brakes. I have cleaned all 4 wheel speed sensors (the rears were really dirty), crossing my fingers that would solve the issues, but the problem still persists.

Where does one go from here? ABS modulator perhaps at fault?

Thanks for your input.

Just because you cleaned them doesn't mean you don't have one dropping out. You have monitor them with a scan tool when slowing and see which one is reading incorrectly.

 

[Xinirgi]

Later gen 4Runners have an electronic assisted brake booster, it cycles on and off during use and is normal. If you don't have any codes lighting up or pending, and you don't have the actual brake pedal pulsating during normal braking, you don't have a problem - it's normal.

 

[ToyotaBrah]

Just because you cleaned them doesn't mean you don't have one dropping out. You have monitor them with a scan tool when slowing and see which one is reading incorrectly.

Understood. Thanks!

Later gen 4Runners have an electronic assisted brake booster, it cycles on and off during use and is normal. If you don't have any codes lighting up or pending, and you don't have the actual brake pedal pulsating during normal braking, you don't have a problem - it's normal.

Ah, I had no idea that the later gens had the electronic assisted boosters, but it makes sense now! Yes, I have no ABS codes or pulsating brake pedal. Thanks!

 

[jgue467]

... Intermittently, the ABS system will prime itself when I apply the brakes.

When you say prime do you mean you hear a pump sound (whirring) or what? I have an '01 but it doesn't make any sounds like that, i did have an acura that would do it occassionally but not necessarily while braking.

That brake boost feature is funky. I call it the 'grandma braking feature', makes me look like a grandma with grabby braking - although the feature might actually help in some situations.

 

[ToyotaBrah]

When you say prime do you mean you hear a pump sound (whirring) or what? I have an '01 but it doesn't make any sounds like that, i did have an acura that would do it occassionally but not necessarily while braking.

That brake boost feature is funky. I call it the 'grandma braking feature', makes me look like a grandma with grabby braking - although the feature might actually help in some situations.

Agreed. I would much rather have a traditional brake booster, as oppose to this algorithmic brake setup that it has....haha.

Found a video on youtube that sounds like what I'm hearing, but for only 2-3 seconds, then it makes that thunk noise.

4Runner HydraBoost System Noise - YouTube

 

[Tommyboy66]

just bought 2001 4 runner. abs lights are on and have buzzer going off. is there a way to fix this?

 

[Ifirefight]

Hi all,

I have recently purchased a 4Runner from Seattle, WA. It has 200K and runs great, with the exception of a few minor issues.

One issue that has me stumped is the ABS system. Intermittently, the ABS system will prime itself when I apply the brakes. I have cleaned all 4 wheel speed sensors (the rears were really dirty), crossing my fingers that would solve the issues, but the problem still persists.

Where does one go from here? ABS modulator perhaps at fault?

Thanks for your input.

Same thing happened on my Sons 2001. It would prime on and off. Was fine for a while, but over time it did it more and more. We took the whole thing off and found it had a small leak on the underside of the brake booster/master cylinder assembly. We ended up replacing it and has been fine ever since. I’m afraid yours will get worse over time.


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[Comebackcarol@gmai]

At my wit's end

Same thing happened on my Sons 2001. It would prime on and off. Was fine for a while, but over time it did it more and more. We took the whole thing off and found it had a small leak on the underside of the brake booster/master cylinder assembly. We ended up replacing it and has been fine ever since. I’m afraid yours will get worse over time.


Sent from my iPhone using Tapatalk

I have replaced tranny sensor and whole ABS assembly but not module under driver's foot. All breaks redone, slave cylinder( which started this)and bled, bled, bled brakes.
Still the loud noise and ABS plus Break light Still on, ebrake adjusted but still weak. No DTCs no pulsing, breaks great but now no speedometer or OD( was down when I bought it but I didnt know). Scares me to drive with all lights on.
Great thread, can y'all give me any help? Anyone?!!