Intermittent Brake Booster Pump Failure

Hello, currently own a 06 runner with the 4.7, and I'm having an issue with my brake booster pump.

The issue is that the brake and the pump are working as they should, and then, without any reason or warning, the brakes will fail, and the brake light and the beeping come with it. Then, after about 20 or so seconds, the system will return to normal operation as if nothing happened.

Sometimes just the brake light will come on without the buzzer, or the warning lights will flash without the buzzer and then go back to normal. The issue is not consistent

Things I've checked

-Fluid is at the proper level.
-No leaks are coming from either the brake booster, hoses, or calipers
-No strange noise coming from the pump when it is operational. It's running in the proper increments

The one thing I will add is that the pump is quite hot to the touch, not sure if that's typical.

I'm planning on ordering a new replacement unit, but I want to see if there is something I can do or check before installing it.

 

Welcome

 

I believe either @4onto or @AuSeeker is familiar with the brakes o this and could possibly help.

 

It's hard to say what part of the ABS/Master Cylinder assembly is causing your issue, it could be the pump, accumulator or the ABS control module on the side of the assembly, but since you say the pump is getting hot I would suspect it as the issue, not even Toyota Master Techs I spoken to understand everything about these assemblies, when they have one come in with such issues they replace the entire assembly, I'm sure there are some Toyota Engineers that know, but if you're replacing the entire ABS/Master Cylinder assembly with a OEM new assembly then rest assured it will solve your issues as there is nothing else that it could be.

 

Thank you for the vote of confidence but unfortunately, I too have limited knowledge of the master cylinder assembly. Instinctively though, it seems like it's losing power momentarily.

 

I couldn't remember which one of you had some knowledge only that one of you knew more than me.

 

Mine been turning the motor on every time I brake. I'm thinking that's not normal but I've not actually had any braking issues.

 

I'm guessing either the pump is not doing it's job or more likely the accumulator or it's O-ring is going bad, a few have replaced the O-ring and solved that issue.

Try and locate a entire unit from a salvage yard to replace yours entirely or for parts.

A new accumulator costs $360 to $450, the O-ring around $5 from Toyota but less using a generic equivalent.

 

And the service manual just says give the pump motor 12V to see if it runs and that's it.

 

Update

Seems like it fully broke now. Turning on the car causes the brake light and buzzer to go off constantly.

Could it be just the motor itself failing? ive seen people online just replacing the motor and solving the issue @AuSeeker

 

It could be...but you can sorta check that by listening to see if the small electric motor is running or not, if it's running and sounds good then it's not the motor.

If the motor is running then it's either the pump or accumulator, but as I mentioned earlier that with your pump getting hot it could be the pump.

If the motor is not running then you can replace it, but you have to remove and reinstall the entire ABS master cylinder assembly to do it and hope it all works, if it doesn't then pull the assembly again and replace more parts, etc. until you fix it, a new motor will cost you at least $500 if you can find one or a rebuilt one for around $300ish and there may be aftermarket options out there, or try and find a good one from a salvage yard.

If you end up replacing the motor and then have to do the pump and then the accumulator before getting it to work correctly you will spend more than a complete new OEM ABS master cylinder assembly would cost.

I replaced my entire assembly with a new OEM because it's my daily driver and I needed it fixed the first time without fail...I believe in the "buy once, cry once" philosophy when it has to be done without fail, the new OEM assembly cost me right $1300 but I did the install myself and save a lot of money on labor.

If money is an issue I would go the salvage yard/used route, you can also find used ones on eBay.

 

This could happen to my 4Runner down the road as it's not getting any younger. A new assembly is more than $3,000 CAD before tax. For that amount, I could buy two or three used ones off of eBay. Then again, what does aggravation cost. Either way, swapping in a whole working unit does seem like the most sensible option.

 

Welcome from Wisconsin!

 

My experience with hydraulics - if a pump or an actuator or a valve or something gets hot - hotter than the rest of the system nearby - the pump could be internally bypassing, or leaking internally. That could explain why your motor runs a lot, trying to keep your system pressure up where it is supposed to be.