2007 4Runner ABS issues

[lugueto]

Hey guys,

We're having some weird behavior from the 4runner's ABS system, it has been going on for a few months now. Here are the symptoms:

When you start the car, and get going, about 5 seconds after taking off for the first time you hear the ABS cycling, but you're not even braking. This only happens the first time you take off after turning the car on.

The ABS kicks in on the slightest bumps or disturbance while normal braking

The ABS light doesn't come on at any time and braking power isn't reduced or braking performance hindered in any way, just the weird activations of the ABS.

The 4runner is a 2007 V6, with close to 60000 miles on the odometer, had discs changed once because they warped. She drove for a while with warped discs, and the brakes do feel a bit long but I think it has always been that way, we have had her since new.

Any ideas with what might be going on??

I appreciate any help

Luis

 

[chitown40]

Are you sure its the ABS and not the pump on the master cylinder/booster? Does the pedal pulsate like the ABS is activating? Did you recently change the brake fluid or run the master cylinder dry, even for a brief moment?

 

[lugueto]

I'm not sure if the pedal pulsates when you take off, because I dont have the foot on the brake when i do so. But the sound is noticeable, maybe even a slight vibration with the sound.

When the ABS activates on the slightest disturbance, it does (as its meant to, only way too sensitive)

I haven't changed the brake fluid. When the discs were changed I was told it was a straight change of discs and pads , no messing with anything else. The system has never been run dry or has ever been dry for that matter.

Any other ideas??

Thank you for your reply!!

Happy holidays,

Luis

 

[lugueto]

Checked today, the vibration/sound on take off does not make the pedal pulsate the way it does when the ABS is engaged. Although you can feel the vibration on the pedal when the system sounds..

 

[chitown40]

Sounds like the pump on the brake booster.

Sent from my SCH-I535 using IH8MUD Forum mobile app

 

[landtank]

my wife's 2003 has ride height control and the air bag compressor kicks inb quite often at those times for a short time. Just a thought.

 

[RCsGX]

What does a air compressor have to do w/ the ABS?

 

[chitown40]

What does a air compressor have to do w/ the ABS?

It probably doesn't. But Landtank was merely throwing out another possible component creating the noise the O.P. described.

The O.P. described two different issues. One clearly sounds like the brake booster pump which normally cycles when the truck is first turned on. He also describes the ABS activating frequently over mild bumps/etc. with no ABS light.

The ABS light should not illuminate unless there is a problem with the system. It does not come on and should not come on during normal braking when the ABS activates.

If the ABS is activating all the time, you might have a problem elsewhere in the brake system. Are the brakes real grabby? What kind of pads and rotors did you replace with?

Maybe the rotors are out of round again and are causing a pulsation in the pedal that you are confusing as the ABS activating.

 

[lugueto]

This 4runner doesnt have height control, so that's not an issue.

I have driven this car very frequently for the last 5 years and this isn't a normal sound.

The rotors are straight, and the slight vibration I get on the pedals is only when the system makes that sound (on the first time you take off after you turn her on, she doesn't sound or make any sort of vibration afterwards) The pads and rotors are Toyota.

I am aware that the ABS light only comes on when there's a problem, which is the reason why I brought it up. The system is behaving oddly but there is no light on to tell you that there's actually a problem

I appreciate the help!!

Luis

 

[landtank]

Honda has had a recall where their cars would activate the brakes suddenly and on their own. A friend of a friend had this on his Oddesy prior to the recall and the dealer blamed it on a dieing battery.

So where's the connection?

Another friend who lives in FL had a boss with a Sequoia exhibiting similar issues with the brakes. I asked about the age of the battery and it was the original one so he changed it out and then everything was fine and has been since then.

I would look into the age of your battery and possibly the connections to it.

My wifes 4Runner is a 2003 and I haven't heard any noises like described but the systems are probably different.

 

[lugueto]

Hmm this might be interesting. This battery is probably 1.5 - 2 years old? I dont think its dying, although I will check it. I will also check all connections to it!

Thanks!!

 

[landtank]

Hmm this might be interesting. This battery is probably 1.5 - 2 years old? I dont think its dying, although I will check it. I will also check all connections to it!

Thanks!!

not sure the brand of battery but I had one of those sears batteries that are supposed to be made by Odyssey crap out after a year and a half in the wife's 4Runner. That was long before it was supposed to.

 

[chitown40]

I did more searching on the subject and got some good info from a Toyota tech over on t4r.org. The noise and vibration at startup is normal behavior for the electric brake booster. Nothing to worry about.

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[lugueto]

Wow thanks for your help!! Now, why has this gotten more noticeable?? If it did cycle before, you wouldn't notice the sound or the vibrations. Why has this changed??

Landtank, I live on considerably warmer weather than you do so batteries tend to wear out quicker!

Thanks for all your help!!

Luis

 

[dslooney]

we have the same issue with an 2007 and 2008 toyota 4runner. The abs pump runs even with just the key on-it is making a screeching sound and it is running constantly. The 08 is not as loud. Did anybody resolve this. Toyota says it is not an issue.

 

[GXO]

Sticky caliper. Had it happen to me. Would slow one side and trigger abs.