Poll on total brake failure in 100 series (5 Viewers)

[bentonrover]

Like some vehicles I have seen master cylinder units fail. Thing I'm wondering is what is the census between maintained brake systems (fluids every 2 years and brake pads/rotors changed long before scraping sounds) to the non maintain rigs that are repaired when fail. Me personally I only use OE parts and do change pads with half remaining. Kinda over kill but I do my own work. My pedal always seem high compared to some rigs I jump into.

 

[RandomUser]

need to be very aware of the necessity to stop immediately -as in within seconds- driving the vehicle if christmas tree lights come on suddenly on the dash

Definitely. If nothing else I'm glad I found this thread to be aware of this.

If I see those lights spamming my dashboard / hear the warning buzzer, then I'm stopping immediately and calling a tow truck.

My SO has her own vehicle and never drives any of mine but if she does I will be sure to drill this into her head as well. But if she did need to borrow mine I'd just have her take the Camry anyway.

 

[RandomUser]

This is why a well working eBrake is a must, they usually like to seize and rust up so make sure to inspect it and use it regularly to ensure proper engagement. Gotta train yourself and others who drives the car to use the ebrake if the primary brakes fail. Put truck in neutral and pull hard on the eBrake

Isn't it recommended to put the transmission into a low gear and then use the e-brake? As opposed to neutral?

 

[2001LC]

Isn't it recommended to put the transmission into a low gear and then use the e-brake? As opposed to neutral?

I'd say yes. Until speed is down to about 5MPH. Then you'll need to slip into "N".

 

[bpe3]

Add me to the brake failure list.

2001 LX470. 238k miles. 83k of them by me. Doubt this rig has ever left the pavement. Spent most of its life in Dallas/Houston. Drove 325 miles round trip (Houston to Austin) on Saturday. No issues. The next morning as I’m backing out of my driveway: solid, audible tone; ABS light, Brake light, other lights and no brakes. I wasn’t stomping on the pedal, but solid pressure was not enough to stop the vehicle in reverse. Should have pulled the -brake. Instead just slammed the shifter into Park. Was going less than 5 MPH. Vehicle stopped. Didn’t have much time to react. My urban-area driveway is ultra short. I was only a couple seconds away from backing into my neighbor’s S600 that was parked on the street.

Will be towed to indie shop tomorrow. This thread has been a great resource.

 

[MountaineerLC]

While I'm not especially worried of a brake failure, this thread has motivated me to rehab my park/ emergency brake and get it in tip top shape.

 

[2001LC]

Sounds like booster motor failure. As it sits overnight the fluid pressure bleeds down. Then jump in start and go. The small amount of remaining pressure is lost as you press the brake to shift.

I'm supper interested in your used parts. 8 to 1 shot the control wire has some corrosion.

I'd also be interested to know your brake fluid level right now. Again after pumping brake pedal 40 times with IG key OFF.

Also if you then turn IG key to ON, too see if booster motor runs and fluid level drops.

 

[Pskhaat]

Sounds like booster motor failure. ... I'd also be interested to know your brake fluid level right now. Again after pumping brake pedal 40 times with IG key OFF. ... Also if you then turn IG key to ON, too see if booster motor runs and fluid level drops.

Maybe I missed a thread/posts in here, but what does this pumping check/reveal?

 

[2001LC]

Mainly I'm interested in level and motor.
If over max line before or after pumping, system is overfilled.
What I'm asking is just to verify booster motor working or not, and what brake fluid level is before and after.

If brake fluid level near max line and booster motor is not working. Pumping pedal will not change level, as accumulator is already evacuated. If on other hand fluid level raises while pumping brake peddle. Then motor must have been working.

Sometimes motor work intermittently. This makes diagnose difficult, as it may run during testing just fine.

If level above max line before or after. Then system was overfilled. Overfilling at anytime in it's history of vehicle, even if not now, has consequence.

If brake accumulator is shot, which is not common in sudden lose. Level may change and motor will likely run after pumping.

If reservoir empty or very low, he likely has a leak. Like a brake line burst. Booster motor will run if its not burned up from continuously running. This not very likely based on description of events prior to failure.

If level changes, is correct and motor runs. It could be a damaged or worn-out master. Not likely.

 

[bpe3]

2001LC-
1. You are welcome to my old parts when they come off.

2. The brake fluid has not been overfilled on my watch. I’m familiar with the filling procedure. Current fluid level is about 3/4 full if the Min line = empty and Max line = full. Pressing the pedal 40 times results in no change in fluid level or pedal feel.

 

[2001LC]

So I'll assume you did not hear booster motor run when IG key turned back ON after pumping pedal?

So very likely booster motor failed. If wire corroded, it's likely was overfill prior to your "watch". That wire is a big deal, that I'm very interested in.

I flied inspect wire, by peeling back boots covering both ends of wire. I'm now recommending replacement of the wire, screws and nuts when corrosion is/if found. It gives opportunity to inspect internals of motor also.

I very much would like your old parts. It is the failure I'm concentrating on in my researching, and will add to my data pool.

 

[bpe3]

Just checked. No sound from booster pump. Not sure exactly what it’s supposed to sound like, but didn’t hear anything of note after turning the key to ON.

 

[2001LC]

With hood open it is very clearly heard. Most people never hear this, as they have radio or cabin fan on. Others that do hear, think it is fuel pump. Actually fuel pump does not run unless engine cranking or running.

A test, FSM recommends after bleeding and we do to check for leaks and health. Is timing how long booster motor runs. After pumping brake pedal 40 times to evacuate accumulator. Turn IG switch (key) to ON, and time how long pump runs. Spec is 30 to 40 seconds. Longer is often a leak or air in system. But can indicate pump or accumulator issue.

Motor Not running, indicates a fault. Most common is bad motor. But must be test to narrow down.

FSM (newer) also has warning. About how long to allow booster motor to run.

Motor is attached to bottom of master assembly.

 

[bpe3]

Good info, 2001LC. Definitely no noise right now. I had the hood open and the driver’s window down.

On the topic of noise though...

As long as I have owned this vehicle, I’ve always heard a low level humming/mechanical type noise whenever the engine is off and the key is on. Never stopped on it’s own. The noise wasn’t loud or bothersome, but I always noticed it. Just loud enough to know something is running. Not noticeable with the engine running.

On the topic of leaks...

Installed new pads, rotors and brake fluid upon acquiring the vehicle. Never found a fluid leak, but got the low fluid brake light a handful of times over a couple of years. Did the 40 pedal presses and filled the reservoir to Max line each time. Then the fluid level held. Haven’t had to top it off in years. Haven’t done any other brake maintenance since either.

 

[2001LC]

Could be throttle-body humming. Not good to keep key on ON when engine is off. Best IG switch is turned to ACC.

Considering, you've been topped off a handful of times and know that level drops as pads wear. Pad form new to worn out, should not drop fluid below minimum. Adding (topping) indicates a leak. Humming could be booster motor, if systems never hitting predetermined stop PSI.

After flushing or bleeding breaks you should test and test periodically. Each time you did the topping procedure you should test. By simple turning key CW to ON (not start) and time the booster motor run time. With hood open, it's more apparent it comes from booster motor. Often you'll see the boost accumulator wobble and vibrate.

At 45 to 48 seconds I find a bleeder or two weeping with an almost undetectable leak. If pump runs none stop you've a serious problem
you've a bad leak.

 

[RandomUser]

So I've been noticing while driving my LC the past few days; the brake pedal will sometimes be pretty "loose"/have a lot of travel, and other times will be significantly stiffer. Braking always works just fine — is this indicative of something wrong? Or is it normal function of the system?

 

[dwh13]

So it finally happened to me - 03 LX, 289k miles, ABS, VSC/TRAC lights on, alarm blaring, and brake pedal went to the floor. Luckily I was in my driveway so I just used the e-brake to maneuver it out of the way of my other car. I had just taken it on a 400 mile round trip with zero issues, went to get in it the next day, and as soon as it turned on, the alarm sounded. Fluid level in the reservoir is fine, no leaks at the lines or calipers, brake fluid is about a year and a half old. I pulled these codes:

C1256 - Accumulator Low Pressure
C1223 - ABS Control System Malfunction

I'm not sure whether the ABS pump is bad or if the master cylinder needs a rebuild? The truck is for sale, so I want to make sure this gets fixed correctly so her next owner doesn't run into this again.

 

[RandomUser]

So it finally happened to me - 03 LX, 289k miles, ABS, VSC/TRAC lights on, alarm blaring, and brake pedal went to the floor. Luckily I was in my driveway so I just used the e-brake to maneuver it out of the way of my other car. I had just taken it on a 400 mile round trip with zero issues, went to get in it the next day, and as soon as it turned on, the alarm sounded. Fluid level in the reservoir is fine, no leaks at the lines or calipers, brake fluid is about a year and a half old. I pulled these codes:

C1256 - Accumulator Low Pressure
C1223 - ABS Control System Malfunction

I'm not sure whether the ABS pump is bad or if the master cylinder needs a rebuild? The truck is for sale, so I want to make sure this gets fixed correctly so her next owner doesn't run into this again.

What scares me is that there are 2 ways people are saying this happens. Some people are saying that once those lights/buzzer comes on, you should still have good braking ability if you pull over immediately and don't pump the brakes. But a seemingly equal number of people say that the second they got those lights/buzzer, it was instant loss of brake pressure.

Really makes me want to never take this thing on a windy mountain road

 

[Pskhaat]

Really makes me want to never take this thing on a windy mountain road

Yeah....I know....

 

[bpe3]

My brakes are fixed.

OEM Brake Booster Pump Assembly - $1,004
Charge for Expedited Delivery - $163 (otherwise dealer said 10-12 days)
Brake Fluid - $5
Installation - $225 (Indie shop)
Sales Tax - $83
Total Repair Cost - $1,480
Plus another $102 to have vehicle towed to the shop.

The codes that appeared were: C1223, C1251, C1252, and C1256.

There was no corrosion on the electrical wire or connection.

I have the old part in hand if you want to take a look at it, 2001LC. Just tell me where to send it.

2001 LX470 with 238k miles.