I discovered an issue with my braking system when a vehicle pulled out in front of me today. The pedal was rock hard and required a lot of force to get it down far enough to actually engage the brakes. This does not happen when I brake under normal stopping conditions, it only happens when I quickly try to press the brake pedal down hard.

I recently changed the brake hoses and put all new fluid in the system and bled it correctly with a partner. The pedal feel improved after I did that so I don't think it's related.

I'm wondering if my brake booster is failing? I've read that a hard pedal is one of the symptoms but I'm not sure since the hard pedal is only during hard stops. Any thoughts or advice is appreciated, thanks.

My old 99' had this issue and a new brake booster seemed to fix it. When you go to replace it, make sure there's not evidence of brake fluid inside as that will obviously be the root problem and will mean the seal of the MC is allowing it to leak into the booster.

I have this issue too, but only in the winter when it’s freezing. Like -25 to -30 Celsius. In the summer and at any other temperature it’s perfectly firm and not spongy at all


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Sounds like a failing brake booster check valve to me. Mine did the exact same thing on cold mornings.

Make sure you replace the grommet that check valve sits in also.

It's only like 25 bucks for both parts, I'd start there.

I had a booster leak . slowly the leak engine on got bigger so at first it did seam a bit hard to press down on a faster harder stop.. then normal easy braking pedal high and hard.. booster was worn over 200K on it..

with the engine off for an hour press down on brake if high and hard its a leak...

master fluid leak into it also causes the seal to break down as well as time and use ..

The valves can be replaced by themselves? I figured I'd have to replace the whole booster assembly which is pretty expensive.

I think I'll probably rebuild the MC anyway if I'm in far enough to replace the booster assembly.

What year is your rig?

I believe the 01/02 its all one assembly.

The check valve on the brake booster on the 96-00 can be removed and replaced. It's stupid simple, takes 5 minutes.

This is 100% the Brake Booster Check Valve if you have a '96 to '00.

These were the parts I ordered for my '97 Limited
1- VALVE ASSEMBLY, VACUUM CHECK (FOR BRAKE) . VALVE,CHECK [44730-60060]
1- GROMMET, CHECK VALVE [90480-24015]

AWESOME! Thank you.

I have a 96. I'll order these parts today.

EDIT: McGeorge Toyota's website says the grommet doesn't fit my 96. Should I assume that's incorrect?

These 3 part numbers should be the same part (all were replaced by/redirect to 90480-24015)

• 90480-24438
• 90480-24517
• 44673-25020

Does the site give you one of those?

That first one says it fits. Perfect, thanks man.

test the check valve and hoses for leaks . check valve flows one way easy to test .

Very interesting, my 99 does this at first on cold mornings, but then it goes away. I'll have to look into this as well.

Hard Brake pedal:
Updating this thread to inform that I replaced my brake booster and have some suggestions. The most difficult part was inside the car. 3 of the nuts were easy, but not the upper right nut which is partially blocked by the brake pedal. I removed it with a socket wrench with 3" extension and DEEP 12mm socket, approaching from the door side of the steering column. To re-install, I had to get the nut started by holding it between 1st and 2nd finger to place it. Will be tough with big hands and don't drink too much coffee. Also you will drop it into the rubber boot around the steering shaft. Fortunately that is held on by velcro. But of course it will then fall behind the carpet and you will pull that up to fish around for it there.

Bad news is I still have the same hard brake pedal when making a downhill stop. Braking feels good for first 3/4 of the stop but by last 1/4, to come to FULL stop, I'm standing really hard on the pedal. Sigh