Weird braking sensation on pedal

[Sporin]

I wonder if this is the same thing I'm experiencing lately... bear with me as I try to explain it...

Light-to-moderate braking, at various places along the smooth pedal travel I "feel" almost a 'pop' within the brakes somewhere. It doesn't feel like it's coming from the pedal itself, but more of a vibration I'm feeling from somewhere else in the braking system. Extremely subtle, but it's happening frequently. The 'pop' almost has a spring like quality to it, as if some part of the system was operating just slightly behind where it should be, then 'pops' into place.

Again, very, very subtle, my wife can't feel it.

Curiously enough, and possibly related, I was getting the 'brake" red light on my dash the other day when accelerating and found I needed to add a little brake fluid.

Second factor is that I just got new tires. Went from very street-biased Laredo Cross Country Tour | Uniroyal Tire to much chunkier Grabber AT2

It makes me wonder if my Master Cylinder or some other part is starting to go. Or if the tire techs knocked something to cause this.

Front calipers were new when I bought the truck in April. No idea on the rears. No excessive heat or smell after braking so I'm not suspecting a stuck caliper thought it seems to always be a possibility with these trucks.

Braking performance is smooth and strong, pedal firmness hasn't changed, nothing bis being extra grabby. Both TC and ABS are working as they are supposed to still.

It'd cold, wet winter here so I haven't gone crawling under the truck to check everything out yet. I'm also loathe to describe the issue to a mechanic and have them charge me a couple of hours labor only to randomly start replacing parts.

Any insights anyone has would be greatly appreciated, thanks!

 

[earthrealm]

i get the same buzz on mine, abou every 8 secs if am at a light with my foot on the pedal, with the engine off and ignition on i feel the pumps kick in every 90 secs..
i think i either have air in the system or my MC is on its way out....
i also noticed the shiny cylindrical metal near the brake fluid reservoir is super hot after driving, hv clocked temps of 65 deg c after under 30mins of driving

only time will tell

 

[M1911]

It's the brake pump. It is normal. My '03 has been doing that since I bought it new.

 

[ben550]

I wonder if this is the same thing I'm experiencing lately... bear with me as I try to explain it...

Light-to-moderate braking, at various places along the smooth pedal travel I "feel" almost a 'pop' within the brakes somewhere. It doesn't feel like it's coming from the pedal itself, but more of a vibration I'm feeling from somewhere else in the braking system. Extremely subtle, but it's happening frequently. The 'pop' almost has a spring like quality to it, as if some part of the system was operating just slightly behind where it should be, then 'pops' into place.

Again, very, very subtle, my wife can't feel it.

Curiously enough, and possibly related, I was getting the 'brake" red light on my dash the other day when accelerating and found I needed to add a little brake fluid.

Second factor is that I just got new tires. Went from very street-biased Laredo Cross Country Tour | Uniroyal Tire to much chunkier Grabber AT2

It makes me wonder if my Master Cylinder or some other part is starting to go. Or if the tire techs knocked something to cause this.

Front calipers were new when I bought the truck in April. No idea on the rears. No excessive heat or smell after braking so I'm not suspecting a stuck caliper thought it seems to always be a possibility with these trucks.

Braking performance is smooth and strong, pedal firmness hasn't changed, nothing bis being extra grabby. Both TC and ABS are working as they are supposed to still.

It'd cold, wet winter here so I haven't gone crawling under the truck to check everything out yet. I'm also loathe to describe the issue to a mechanic and have them charge me a couple of hours labor only to randomly start replacing parts.

Any insights anyone has would be greatly appreciated, thanks!

Did you ever find out what that pop you felt was? I have the same thing and its very subtle. Only an alert/attentive driver will notice it. I was thinking it might be a problem somewhere in the master cylinder... etc... Would love to know if you figured it out.

It's the brake pump. It is normal. My '03 has been doing that since I bought it new.

Were you referring to this pop in the brake pedal or the other posters comment?

 

[M1911]

Were you referring to this pop in the brake pedal or the other posters comment?

I was referring to the buzzing sound/feel from the brake booster bump. It's normal.

 

[Sporin]

Did you ever find out what that pop you felt was? I have the same thing and its very subtle. Only an alert/attentive driver will notice it. I was thinking it might be a problem somewhere in the master cylinder... etc... Would love to know if you figured it out.



Were you referring to this pop in the brake pedal or the other posters comment?

I'm suspecting that my issue isn't the same as what is being described here now that I'm also losing a litle bit of fluid.

See: http://www.toyota-4runner.org/4th-gen-t4rs/185964-losing-brake-fluid-very-slowly-where.html

I'm getting it into my trusted local garage asap to investigate as I suspect the tire place did something accidentally that they didn't own up to when I got my new tires and a full alignment (they took forever to do it, I wonder if they knocked something).

 

[earthrealm]

SO sadly today @ 130200 miles, my brake system/MC failed......just came back from a 20mile round trip during my luch break, car was ok, parked the car...got back to work, 3 hrs later i enter the truck to drive home, as soon as i start the car and engage gear, i hear a high pitched warning sound and all the lights on my dash light up, brakes rare pretty useless, gotta stomp on them with all my might b4 the truck stops.....

i have had the buzzing/pulsing brake pedal issue for 2 yrs now, so i guess it has finally crapped out, dont have the $$$$$s for a new MC/brake system, so i intend to pick a used unit from ebay, and go from there...........need to figure out how to manually bleed the brakes after swapping out the bad unit
[MENTION=66389]BlackWorksInc[/MENTION] i guess anyone with a similar pulsing brake issue, shoud prep for the day it craps out


LOOKING AT PICKING THIS UNIT FROM EBAY.
http://www.ebay.com/itm/ABS-Brake-P...005|Model:4Runner&hash=item3f43b3ba91&vxp=mtr

 

[AKmoney]

Sorry to hear about this... Hope you get the truck running soon.

FWIW, I bled the brakes on mine this past weekend. Pretty much like any other car except for the rear brakes which were actually a little easier. Rather than have your helper pump the brake pedal while you open/close the bleed valve, all they have to do is apply pressure to the pedal when you open the valve and the hydraulic pump will turn on and pump out the fluid in a continuous stream. Let it pump until the fluid is clear and you're done. Just make sure the reservoir never falls below the "Min" line. The front brakes required the more standard 2-person procedure.

BTW, my truck has always made the noise/click from the hydraulic pump. It's pretty subtle. You can hear it if the radio is off and you're just tooling around slowly in a parking lot (windows up). It tends to cycle on every 2-3 times you use the brakes. I think it's normal but it *is* unfortunate that when they do die, they're pricey fixes.

 

[m85476585]

Sorry to hear about this... Hope you get the truck running soon.

FWIW, I bled the brakes on mine this past weekend. Pretty much like any other car except for the rear brakes which were actually a little easier. Rather than have your helper pump the brake pedal while you open/close the bleed valve, all they have to do is apply pressure to the pedal when you open the valve and the hydraulic pump will turn on and pump out the fluid in a continuous stream. Let it pump until the fluid is clear and you're done. Just make sure the reservoir never falls below the "Min" line. The front brakes required the more standard 2-person procedure.

BTW, my truck has always made the noise/click from the hydraulic pump. It's pretty subtle. You can hear it if the radio is off and you're just tooling around slowly in a parking lot (windows up). It tends to cycle on every 2-3 times you use the brakes. I think it's normal but it *is* unfortunate that when they do die, they're pricey fixes.

You can also use a TIS Techstream cable and it will bleed the brakes for you, I assume all four wheels one at a time. That's probably the safest way to do it, since it's the way Toyota intended.

You could also do pressure or vacuum bleed, but it may be less safe for the hydraboost unit.

It's a really good idea to change out the brake fluid on a regular basis since fresh fluid works better and should inhibit corrosion (no water). [MENTION=78511]earthrealm[/MENTION] might have just had a minor problem that caused the pump to run too much (every 8 seconds), that could have been fixed by bleeding. But it sounds like the pump running too much eventually overheated it or burned it out. Fresh brake fluid should also help with the stuck caliper issue, or at least it can't hurt.

I plan to do mine once I get a cable, and next time the weather is nice.

 

[M1911]

Where did you get the TIS Techstream cable and software?

 

[m85476585]

I haven't bought it yet, but many people get them on Amazon. There are a few long threads with people having issues getting them to work. It should work eventually, but maybe not out of the box.

 

[earthrealm]

pls confirm this is the techstream, i intend to buy it, and use it to bleed the ebay MC unit i intend to buy.

Amazon.com : Fotga Newest V8.00.034 MINI VCI for TOYOTA TIS Techstream Diagnostic Cable & Software : Toyota Mongoose Cable : Automotive

 

[m85476585]

You'll have to consult some other threads to make sure it will work.

http://www.toyota-4runner.org/gener...ta-tis-techstream-8-x-windows-7-8-64-bit.html
http://www.toyota-4runner.org/4th-gen-t4rs/130169-tis-techstream.html
http://www.toyota-4runner.org/5th-gen-t4rs/121604-toyota-tis-techstream.html

Some of those threads have old information at the beginning, so make sure you find up to date info about what will work.

The cable you linked to is probably the one I will buy. Note that these are knockoffs of the real thing, so it might not work as well as what the dealer has. As in, it may be difficult to get it working with your laptop, and some people report that some of the functions are disabled. There's some risk that you will buy one and it won't work for some reason (or for no reason, if it's defective).

 

[earthrealm]

oh and again, hope its not a stupid question...but is there a way to test/check the MC before installing it in the car?...since am buying used from ebay.

 

[awdjunkies]

oh and again, hope its not a stupid question...but is there a way to test/check the MC before installing it in the car?...since am buying used from ebay.

Unfortunately, from what I've read, the answer to your question is No..

 

[earthrealm]

UPDATE: i gave the abs motor, several knocks with the ignition on, and it grudgingly kicked on, after a few pumps, it has returned back to normal [the way it was before], with the car off, and the ignition off, it kicks in every 70 to 80 secs, and kicks in everytime the brake pedal is depressed.. based on this, could anybody with experience confirm if this is a sign of having air in the system or a leak??......

attn: [MENTION=113611]m85476585[/MENTION] , [MENTION=66389]BlackWorksInc[/MENTION]

 

[m85476585]

with the car off, and the ignition off, it kicks in every 70 to 80 secs

With the car off? That's going to drain your battery. I don't know if or how much it's supposed to run with the car off. One time I heard a pumping noise from a friend's truck when he wasn't around, so maybe it was the brake pump and maybe it runs sometimes when the car is off. It makes sense so that you have brakes right away when you start it.

I don't think mine comes on every time I press the brake, but probably most of the times. If I hold the brake pedal down with constant force, it might come on once a minute. I haven't noticed it come on when I'm not using the brakes, except when I start the car.

Now that you got it working, try changing out the brake fluid if you haven't done it yet. Even if you do it the manual way without a Techstream cable, it could help. Doing it with the computer may be a bit better in this case, if there's air in the hydraboost unit.

If the pump is running too frequently it might overheat or burn out. A leak somewhere could cause it to run too frequently.

I'm not an expert on this, but I'll try to experiment if I go for a drive today.

 

[earthrealm]

no, you misunderstand me, the pumps kick in every 70/80 secs with the ignition on, without the key, the pumps dont come on.....so battery is not being drained

ok thanks, i suspect a leak, cos for the pump to keep coming in every 70 to 80 secs with the car off, then it means that the pressure is failing/leaking somewhere, yes, will drain and replace the fluid to see what happens, though that will be in 2wks time...gonna be out of town for sometime..

 

[BlackWorksInc]

UPDATE: i gave the abs motor, several knocks with the ignition on, and it grudgingly kicked on, after a few pumps, it has returned back to normal [the way it was before], with the car off, and the ignition off, it kicks in every 70 to 80 secs, and kicks in everytime the brake pedal is depressed.. based on this, could anybody with experience confirm if this is a sign of having air in the system or a leak??......

attn: [MENTION=113611]m85476585[/MENTION] , [MENTION=66389]BlackWorksInc[/MENTION]

Sounds like the motor is going bad. That's typically the way you test for a bad starter (dead winding) is by tapping it to get the starter to turn slightly and engage the next winding, until the next time it stops on the dead spot and the car won't turn over.

Sounds like motor section is toast to me, probably part of the buzzing you heard for so long.

 

[m85476585]

I tested mine today, and I can confirm that the pump does not come on when the ignition is off. I pumped the brakes for about a minute with the ignition off, and the pump never came on.

The pump in mine runs for 1-2 seconds every other time I press the brakes. There's a slight buzzing sound, but I don't know if it's normal.