Changing brake fluid

There is a "fluid replacement procedure" given in the repair manual that you can follow without needing a scan tool.

Toyota Service Information and Where To Find It | PriusChat

I think a bunch of existing threads here describe it. Best to follow that procedure.

Keep in mind that a job is only "fluid replacement" if there is no air in the system to start with, and if you take total care the reservoir never gets too low and no air gets in while you're replacing.

Otherwise, it becomes an "air bleeding" job, and there isn't a no-scantool procedure for that.

 

FWIW; hopefully you disconnected the battery before you sucked the brake fluid out of the reservoir. The system does periodic testing and if the brake test was triggered while it was empty; it would've sucked air into your brake system. This isn't an old simple hydraulic brake system; there's a pump and ecu atttached to it.

 

I’ve done a couple of non-Techstream brake fluid replacements; it’s a straightforward procedure, works.

Some links, tips and repair manual excerpts in my signature. Worthy of note: the parking brake must be applied for the “invalid mode” to activate.

(on a phone turn it landscape to see signatures)

 

you need to put the car into invalid mode to bleed the rear brakes since it’s controlled electronically. The fronts you can bleed the brakes conventionally by having the car off and pumping the brake pedal and hold and opening the bleeder valve.

 

When there's no air in the system (you just want to do "fluid replacement") that works ok.

"Bleeding" (which traditionally means "getting air out") is more complicated: the actuator has multiple fluid pathways (for normal use and for fail-safe use), with electronically-operated valves between them, controlled by an ECU. Attempts to do what you'd do to bleed your grandpa's brakes don't get the air out of all the places, except when you're using the scan-tool bleed procedure that operates the valves at the right times.

 

I recently tested the brake fluid on my 14 year old 2012 Prius v.

I used both the Phoenix dip strips and the moisture test light.

The strip show no degradation and the light showed no moisture.

I was going to have my dealer bleed and change the fluid, but now found that it isn't necessary.

 

Well good luck. There is a Toyota sanctioned process, Techstream not required, battery left connected, car put in “invalid mode”.

 

Post 7... Georina...14 years and no moisture degradation/ absorption to the brake fluid?

Is there more to the story?
Toyota caliper piston design, reservoir cap quality the best, for examples?
I am just "blown away" by the 14 yr time span

 

No issues. I has a 1998 Mazda that show no degradation in the fluid when measured with the Phoenix dip strips that I traded in in 2016.

Brake fluid degrades only in two ways. It is hydroscopic and absorbs moisture or becomes acidic.

If none of the two occurs, it's just fine.

Since Brake fluid does not affect EPA mileage ratings, factory recommended 24 month replacement is a big money maker for dealers.

On the reverse, extended oil changes save manufacturers money when they are included free with a new vehicle purchase and is a good selling point for those not wanting to be bothered with having to take the car in to be serviced.

The free oil change represents an opportunity to sell more services to the dealer.

Long oil change intervals result to high engine wear and sludge. By that time when those conditions occur, the warranty has expired. It's another opportunity to sell the owner a new vehicle.

 

Unfortunately, unscrupulous dealers can use the dip strips with falsified results to sell a brake fluid flush, especially when it is recommended in the owner's manual.

The dirty cabin filter scam made by displaying a dirty filter not even from the owner's is a common scam to sell an overpriced replacement.

That's the main reason to do your own tests.

 

How come? The Repair Manual has a non-Techstream method, for brake fluid replacment. It's worked fine for me. No need for vacuum pump; just an assistant to push brake pedal.

 

If you’ve got neighbours with teenage kids it’s an easy hour’s work.

Put the car in invalid mode, go by the book, is my advice. Basting and replacing coolant in reservoir before you start is a good ploy, not mentioned by Toyota. Also good to have the 12 volt battery on a maintainer, for the duration, since the car is “on”, but not in “ready”.

 

Brake fluid absorbs moisture. The cap is a vent. Not replacing it every 2-3 years is inviting bad issues.
Just because it hasn't happened, yet, doesn't mean it won't.
You can't rely on test strips.
It's called preventative maintenance for a reason. Don't wait until you have a problem, it's too late.

You might as well NOT change the oil and filter until it fails. It's still working, why change it.

Just because someone claims they've gone 10, 15, 20 years without changing the brake fluid,
means it's true......

 

The difference is that the brake fluid is in a closed system. While the cap is vented, very little air is drawn into the master cylinder from years of use. If moisture is drank in to contaminate the brake fluid, it will become electricity conductive. Non conductive fluid contains no water.

Likewise,the pH of the fluid will indicate the level of acidity and degradation.

When either condition is indicated in a yearly test, t h e fluid needs to be charged.

The engine oil is affected by an open system with continuous blowback of combustion cases and detritus from mechanical wear and particles drain in that pass the filter. Totally different.

 

Brake fluid is pumped in and out of the reservoir. It's NOT a closed system.
It absorbs the moister in the air, then spreads through the rest of the brake system.
That's why calipers get the nasty corrosion behind the pucks....

 

All hydraulic systems have a slow leak as brake fluid coats the seals in the wheel cylinder pistons with a thin coating of brake fluid.

When brakes are applied the piston moves out with the thin coating as a seal.

The brake fluid level in the naster cylinder goes down with brake pad wear and less with that used to coat the master cylinder seals and caliper seals with use.

If the seal in compromised, a suction condition will draw debris and moisture into tye caliper. That is the way how most moisture enters the system. With repeated brake use, the moisture will eventually be distributed throughout the entire brake system.

If no moisture is detected, the system is fine.

Flushing the system will not damage it, if done correctly.

If poorly done, it will damage a v well functioning system.