Bleeding Brakes on '01-'02 4Runners

[MadCityRich]

Hi,

I was following the brake bleeding thread from a while back and wanted to follow up on a specific technical question. Here's the key paragraph dealing with bleeding brakes on an '01 or '02 4Runner:

You can bleed the accumulator yourself at home. Have the ignition in the "OFF" position, and repeatedly press and release the brake pedal until you get a firm pedal (if it's air in the accumulator, you should eventually get a firm pedal, if you don't, it's air elsewhere). Once you get the firm pedal, take your foot off the brakes, and turn the ignition to "ON". You'll hear the brake booster pump start. It should shut off after approx 30 or 40 seconds max. If it doesn't, turn the ignition to "OFF" again, and repeat the above procedure until it does.

After that, you bleed your brakes the same as on any other vehicle with the pump/hold method except that you do it with the ignition switch in the "ON" position. That allows pressure to your rear brakes on this type of system. Otherwise, you'll have 0 psi at the rear brakes (which you probably already know.)

As an alternative, you can build a cheap power bleeder like I did here and give that a shot. Using this method, you don't need the ignition in the "ON" position. You simply pressurize the reservoir, then crack open the bleeders one at a time.

I have the Motive power bleeder and built the adapter plate that allows for securing the cap to the top of the reservoir. Last summer I did the Tundra brake upgrade and could not get the brakes bled properly. I took it to the dealer to get it finished. Tons of air in the line. I did the whole ignition on/off thing which helped, but didn't get it all done.

What I'm wondering is if, when using the Motive pressure bleeder, the ignition needs to be "on" in order to keep things properly pressurized. When I did it with the bleeder, I started the cycle with pumping the brakes and turning the ignition on, letting the accumulator pump run, then turning the ignition off. I then proceeded to use the pressure bleeder. Should the ignition be on when using the power bleeder?

Thanks for any insight,

MadCityRich

[Bob98SR5]

rich,

subscribing. i'd like to add it to my writeup.

thanks,
bob

[Bighead]

According to the FSM, you need to leave the ignition on while doing the bleed process. Would having a copy of the '01 bleeding instructions help you guys?

[GSGALLANT]

According to the FSM, you need to leave the ignition on while doing the bleed process. Would having a copy of the '01 bleeding instructions help you guys?

That's only when using the brake pedal bleeding method and that only applies to the rear brakes. The FSM doesn't go through a process for a power bleeder, and no the ignition does not have to be ON to bleed the rear brakes (or the front brakes) when using a power bleeder (or anything else) to pressurize the fluid reservoir on an '01 or '02 4Runner.

[Bighead]

That's only when using the brake pedal bleeding method and that only applies to the rear brakes. The FSM doesn't go through a process for a power bleeder, and no the ignition does not have to be ON to bleed the rear brakes (or the front brakes) when using a power bleeder (or anything else) to pressurize the fluid reservoir on an '01 or '02 4Runner.

Hmmm, my '01 FSM says that leaving the ignition on is for both front and rear. The second part of your post makes sense to me even though I don't use a Motive/home brew pressure bleeder.

[GSGALLANT]

Hmmm, my '01 FSM says that leaving the ignition on is for both front and rear. The second part of your post makes sense to me even though I don't use a Motive/home brew pressure bleeder.

Sorry... let me clarify. It doesn't hurt anything to leave the ignition switch to ON when you're bleeding the front brakes, but it is not required when doing the pump-hold method (it is probably required for the sections that you would use the Toyota hand-held tester or the ABS actuator checker, which isn't required for a normal flush, and I've never had air elsewhere in the system to deal with, so I'm not sure.) The reason it is required for the rear brakes with the pump-hold method is because the pressure to the rears comes directly from the accumulator on our systems. If you have 0 psi in the accumulator, and you press the brake pedal, you will have 0 psi at the rear brakes.

[YotaFun]

Bumping an old thread with the Technique I learned while I was at Toyota to bleed these systems using the brake pedal method:

Top off the reservoir and open all 4 bleeders and let the truck gravity bleed first.

After you are sure you have good fluid at all 4 corners, close the bleeders and top of the reservoir.

So you can NOT bleed the hydro-boost system in the 01+ 4Runners, FJ Cruisers, and pretty much any Toyota SUV or truck that has a hydro-boost system the same way you bleed older style Brake systems due to the accumulator attached to the booster.

So this is what has to be done every time a caliper is changed or anything is done to the brake system, even if its just one think you changed (i.e. one caliper, brake line, etc.).

First you have to bleed the rear brakes, since these get pumped straight off the accumulator you do not need to pump the brakes first before you crack the bleeder.

To ensure the accumulator is pumped up, key the truck on but not the engine and listen for the accumulator pump to turn on (on the brake booster on the fire wall), if it does, wait till the pump stops then key the truck off, if you don't hear it run it should be good to go then.

With The key off you are going to hold the pedal, not pump, and crack the passenger rear bleeder and let fluid run till you see no air. then close it.
Then turn the key on but not the engine. You will hear the pump run to fill up the accumulator, once the pump has stopped running, start the truck and let it fun for about 5 seconds, Then turn the engine and key off.

Repeat steps above for the driver rear.

This just covers the rear there is more for the front....

Now, Move to the passenger front caliper, pump the pedal 20 times (yes 20 times, some Toyota techs say even 25-40 times) and then hold, crack the bleeder and let the pedal drop, close the bleeder, turn the key on engine off and let the pump run again, once the pump stops, start the truck, let it run for 5 seconds and then turn the engine and key off.

Repeat the above process again till you get just fluid out of the passenger front.
Once done move to the driver front and do the same process to the driver side as you did on passenger.

Once all air is out, pump the pedal 40 times, turn the key on and let the pump run, once it stops, turn the engine on, and you should have an awesome pedal again!