Possible Master Cylinder Failing??

[Brian757]

Alright, so here is my dilemma:

I currently have the VSC TRAC, TRAC OFF & ABS lights on, and have tried reading the codes for them. Turns out that there are no stored codes in the ECU, and I checked with an AdvanceAuto diagnostic tool and an O'Reillys tool. O'Reilly's tool said that it checks ABS as well, and still came up empty.

I have also noticed that horrible sound that everyone blames the brake booster for, is noisier than ever, and my 13WL brakes seem a bit mushy.

Also, I've also noticed very recently that when I take light turns, my TRAC system beeps, notifying me that I am losing control, but I am nowhere near articulation. My TRAC OFF light is even on, so how is my system operating?? (So should I do a Zero Point calibration?)

Is my master cylinder failing? If anyone needs way more info or could guide me through the process of checking a bad one, that would be huge.

I found this thread on it, but would like some input:
VSC TRAC, TRAC OFF, ABS lights -No check engine - YotaTech Forums

 

[Brian757]

Would anyone at least know if it is normally the master cylinder? Or is it the brake booster?

 

[fourwd1]

So everyone is blaming this noise on the brake booster, your brakes feel mushy, and you think it might be the brake MC. Did I get that right ?

A noise from the booster would be from a vacuum leak, which might also make the engine run rough for a sec when the pedal is pushed. It would also make the pedal feel hard, not mushy.
The MC could fail several ways, two being an internal leak or an external leak.
An internal leak is where fluid seeps past the piston inside as pedal pressure is applied.
A typical symptom would be you push on the pedal, have normal feel and braking, then the pedal slowly sinks to the floor.

An external leak is self explanatory. You push on the pedal, fluid squirts out somewhere, and hopefully you come to a stop. When you release the pedal air gets into the system, and your pedal gets mushy.
Air could get in other ways too and give you a mushy pedal.
Does the MC reservoir get low on fluid?
Have you tried bleeding the system?

 

[gs300tt]

So everyone is blaming this noise on the brake booster, your brakes feel mushy, and you think it might be the brake MC. Did I get that right ?

A noise from the booster would be from a vacuum leak, which might also make the engine run rough for a sec when the pedal is pushed. It would also make the pedal feel hard, not mushy.
The MC could fail several ways, two being an internal leak or an external leak.
An internal leak is where fluid seeps past the piston inside as pedal pressure is applied.
A typical symptom would be you push on the pedal, have normal feel and braking, then the pedal slowly sinks to the floor.

An external leak is self explanatory. You push on the pedal, fluid squirts out somewhere, and hopefully you come to a stop. When you release the pedal air gets into the system, and your pedal gets mushy.
Air could get in other ways too and give you a mushy pedal.
Does the MC reservoir get low on fluid?
Have you tried bleeding the system?

The 2001-2002 has an electric booster no vacuum at all. Do the zero point cal and an deceleration sensor cal before you do anything else.

 

[Brian757]

So everyone is blaming this noise on the brake booster, your brakes feel mushy, and you think it might be the brake MC. Did I get that right ?

A noise from the booster would be from a vacuum leak, which might also make the engine run rough for a sec when the pedal is pushed. It would also make the pedal feel hard, not mushy.
The MC could fail several ways, two being an internal leak or an external leak.
An internal leak is where fluid seeps past the piston inside as pedal pressure is applied.
A typical symptom would be you push on the pedal, have normal feel and braking, then the pedal slowly sinks to the floor.

An external leak is self explanatory. You push on the pedal, fluid squirts out somewhere, and hopefully you come to a stop. When you release the pedal air gets into the system, and your pedal gets mushy.
Air could get in other ways too and give you a mushy pedal.
Does the MC reservoir get low on fluid?
Have you tried bleeding the system?

Thanks for the reply fourwd1! Some requested information:

• Bled all brakes, No air in the lines
• Brake fluid reservoir always stays at Max line
• The loud sound comes from MC/Brake booster unit
• Let me know if you want a video
• Have not done Zero Point Calibration yet

The 2001-2002 has an electric booster no vacuum at all. Do the zero point cal and an deceleration sensor cal before you do anything else.

I have yet to do the 0 point calibration, and will do it when i get home, and to level ground aka "Garage."

One question: Typically people say that prior to a "Zero Point Calibration," only their "VSC TRAC & TRAC OFF" lights are on, but I also have a "ABS" light on as well. Makes me wonder about my brake booster/MC.

 

[chadsy]

Test/clean each of your wheel speed sensors.

Mine was doing something similar so I removed each of them and cleaned them up with a rag. Fixed the issue right up.

 

[01thunder]

what is a 0 point calibration?

 

[gs300tt]

One question: Typically people say that prior to a "Zero Point Calibration," only their "VSC TRAC & TRAC OFF" lights are on, but I also have a "ABS" light on as well. Makes me wonder about my brake booster/MC.

The deceleration sensor can cause the ABS light to be on. After I did the 0 point cal my ABS light was on untill I did the deceleration cal.

It is worth a try as it is free and easy to do.

 

[Brian757]

The deceleration sensor can cause the ABS light to be on. After I did the 0 point cal my ABS light was on untill I did the deceleration cal.

It is worth a try as it is free and easy to do.

Great information. Can you locate a "How-To" for the deceleration calibration?

 

[gs300tt]

Great information. Can you locate a "How-To" for the deceleration calibration?

"I did the calibration today using your instructions and ran into a problem. After resetting the yaw sensor I did a test drive and the VSC TRAC and VSC OFF lights came on as soon as I started moving. I read through the procedure in the FSM and noticed that it says to calibrate the deceleration sensor after calibrating the yaw sensor, before driving the vehicle. So to add to your instructions the procedure for the deceleration sensor is

1. Connect terminals T1 and ES again
2. Turn the ignition on
3. Check that the VSC TRAC light is on for about 4 secs and then starts blinking at 0.13 sec intervals
4. After the light has been blinking for 2 secs turn the ignition off
5. Remove the jumper wire"


From this link

01-02 4Runner How to Zero Point Calibrate your VSC system. - YotaTech Forums

 

[Brian757]

"I did the calibration today using your instructions and ran into a problem. After resetting the yaw sensor I did a test drive and the VSC TRAC and VSC OFF lights came on as soon as I started moving. I read through the procedure in the FSM and noticed that it says to calibrate the deceleration sensor after calibrating the yaw sensor, before driving the vehicle. So to add to your instructions the procedure for the deceleration sensor is

1. Connect terminals T1 and ES again
2. Turn the ignition on
3. Check that the VSC TRAC light is on for about 4 secs and then starts blinking at 0.13 sec intervals
4. After the light has been blinking for 2 secs turn the ignition off
5. Remove the jumper wire"


From this link

01-02 4Runner How to Zero Point Calibrate your VSC system. - YotaTech Forums

You da man!!!
I sent some rep points your way.

 

[Brian757]

"I did the calibration today using your instructions and ran into a problem. After resetting the yaw sensor I did a test drive and the VSC TRAC and VSC OFF lights came on as soon as I started moving. I read through the procedure in the FSM and noticed that it says to calibrate the deceleration sensor after calibrating the yaw sensor, before driving the vehicle. So to add to your instructions the procedure for the deceleration sensor is

1. Connect terminals T1 and ES again
2. Turn the ignition on
3. Check that the VSC TRAC light is on for about 4 secs and then starts blinking at 0.13 sec intervals
4. After the light has been blinking for 2 secs turn the ignition off
5. Remove the jumper wire"


From this link

01-02 4Runner How to Zero Point Calibrate your VSC system. - YotaTech Forums

Nothing happens when I short the circuits together. I've tried it multiple times, the gauge lights do nothing. I tried it with straightened paper clips and wires.

 

[4Runner4TW]

I just replaced the brake booster in my truck last weekend. Pedal was rock hard, but no lights ever came on. So I don't think it would be that..

 

[gs300tt]

Nothing happens when I short the circuits together. I've tried it multiple times, the gauge lights do nothing. I tried it with strightened paper clips and wires.

I have fallowed this exact procedure before and it worked. Does your master look like this?

Or does it look like the old vacuume style. If the lights do not flash at all you may be dealing with a bad part either a master or ABS computer. i am not sure if your year has a seperate ABS computer or it is built in to the ECU.

 

[Brian757]

I have fallowed this exact procedure before and it worked. Does your master look like this?

Or does it look like the old vacuume style. If the lights do not flash at all you may be dealing with a bad part either a master or ABS computer. i am not sure if your year has a seperate ABS computer or it is built in to the ECU.

Mine looks exactly like that.

 

[gs300tt]

Mine looks exactly like that.

If that is the case as much as it pains me to say this you may want to have a dealership look at it. The lights should be reacting to jumpering out the connector. If the master is bad it is quite expensive even used and it still might not be the problem. Have you tried hooking up a good scanner that reads more than OBD2 codes? Most good shops will have a Snap-On or similar scanner that can read deeper than the store bought kind. Sorry the re-calibration did not work.

 

[Brian757]

If that is the case as much as it pains me to say this you may want to have a dealership look at it. The lights should be reacting to jumpering out the connector. If the master is bad it is quite expensive even used and it still might not be the problem. Have you tried hooking up a good scanner that reads more than OBD2 codes? Most good shops will have a Snap-On or similar scanner that can read deeper than the store bought kind. Sorry the re-calibration did not work.

Oh no worries man, I figured I would have to bring it to the professionals. I would like to get the codes read, but do not have the time.

I've been DD'ing it, and it doesn't have actual braking problems. I don't notice a single braking issue, but the sound upon initial daily start-up is horrible. Sounds like a goose is stuck in my engine bay.

 

[infamousRNR]

Oh no worries man, I figured I would have to bring it to the professionals. I would like to get the codes read, but do not have the time.

I've been DD'ing it, and it doesn't have actual braking problems. I don't notice a single braking issue, but the sound upon initial daily start-up is horrible. Sounds like a goose is stuck in my engine bay.

Hey B-Rye.... did you ever figure this out>?//....

 

[infamousRNR]

Bump