Is my brake pedal suppose to be this stiff (new to me hydro assist tundra)

New here, so be kind please. I just bought a used 05 Tundra Limited DC w/129k miles. I've had it for about three weeks and the brake pedal is not improving. I only just uncovered the fact this truck has the massive and complicated hydro-assist brake booster that I am completely unfamiliar with. The brake pedal is stiff as can be. In fact I'm not sure it even moves unless i really stomp on it. I have nothing to compare the pedal feel to since I've never driven a vehicle with such a brake system. Is it 'normal' for the brake pedal on such a system to be so stiff. If not, what culprits should I begin looking for? In my googling i keep finding very little info on these brake booster systems. Brake fluid level appears good, I don't see any visible signs of fluid leaks from the power steering line or anywhere around the master cylinder.

I will add that the stopping power is there, but the way it acts is very different from other standard brakes. I'll apply pressure to the stiff pedal to where I feel stopping power, but then the brake power increases slightly half second later. This leads me to think the brakes are not performing correctly and am constantly trying to judge my braking performance. Thanks for any helpful input.

 

To me it sounds like a bad sensor in the hydro assist booster. They have a sensor in them to indicate rapid pressure change. Usually causes pretty stiff braking. Sometimes this can also cause noise or sudden sponginess, I’m not an expert but I might start there.(Edit) The sensor itself might not be related to the brake system but might be in the power steering system since it measures the hydraulic pressure for brake assistance.

 

I'll look into that. I should've also mentioned the power steering feels and sounds normal

 

Members in the 1st Gen forum probably can't help...

 

Aww, why not?

 

Because we're elite snobs?

 

Shame on us

 

Power steering isn't involved in these boosters. They provide assistance by use of the ABS pump and actuator. Do you have any ABS light on or any codes?

 

Sorry, my bad...I thought OP was the 2012 Crewmax. Never mind....

 

Welcome to the forum, @CMPtundra

If you haven't caught it yet, this is a mandatory 1st Gen read, our collective community knowledge: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

Within the first half-dozen sentences, you'll see links to all kinds of helpful info, including factory service manuals, which will help with braking and adjustment for your truck, and maybe help you understand the system.

I'm not saying it's your problem, but a lot of braking issues with these 1st Gen trucks originates at the rear of the truck, either with the LSPV (if present) or rear drum adjustment. To the point there's a whole thread on properly adjusting the rears.

Be wary, not everyone checks what year/make/model you're running, and some folks with newer or older trucks may give non-specific advice.

Can you tell us, do you have a "Auto LSD" button in your dash, in the same section as the clock?

 

Yes to all the above lol. I did see the sticky thread, and i have taken note of the rear adjustment issues and I will be investigating that. I do not see the LSPV anywhere, but i might have missed it. I have two separate brake lines coming back from under the bed that then come down as rubber brake hose above the diff pumpkin. I mistakenly thought this brake booster was some how intertwined with the PS because of the first response I got. But after more reading and poking around under the hood, I can see clearly it is not. I have the AutoLSD as you mentioned shifty. I also downloaded the FSM pdf from one of the threads I came across on here, and that helped me test the booster (booster function checked out per the FSM test procedure). I also have zero warning lights coming up. the CEL does pop up randomly for an o2 sensor, and along with it the VSC and curve line light come on. But I erase the code, and all lights stay off for a while.

My reason for posting this thread was mainly to get an idea of what type of brake feel and performance I should expect since I have nothing to compare it to with the new fangled brake booster thing. Currently, I do not like how it feels, but if that is normal performance so be it.

I did have a 2000 tundra that i bought from my dad several years ago and used it as a my work truck pulling a small trailer, but was involved in an accident 7 months ago and insurance totaled the truck it still hurts to talk about. I loved it, and loved working on it. But this Tundra is very different from my dad's tundra. My other truck is a Tacoma that I DIY on quite a bit as well.

 

You have one of the unicorn setups, it sounds like. I'm not 100% sure but fairly positive the VSC trucks (AutoLSD) don't have the LSPV. You'll know immediately if you've got it b/c you'll have this armature I'm highlighting in yellow. And if you follow that upper arm to the driver side framerail, you'll find the LSPV.

If I gave you any advice, it'd be to download your FSM for 2005-2006 Tundra in that sticky thread, and find the instructions for how to properly bleed and adjust that setup with the little booster keg. Someone on here mentioned it was easy because there's some way you can get it to start automatically pumping fluid?

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yes that is correct. however i'll need the big boy ECU scanner to manipulate the actuator into bleeding the system. I definitely do not hat the LSPV. I've seen that phrase a few times used to describe this setup, the "unicorn". Why is it referred to as such?

I'm going to take a closer look at the rear brakes prior to anything else though.

 

Unicorn because it’s friggin impossible to find the parts, I believe. Hope you never need to replace things because like $1k+

 

I thought the unicorn mc was the funky 2 piece.


Was hydroboost installed on the factory supercharged trucks?

 

I think there are two. The 2pc is equally expensive.

 

Never seen a hydro boost unit on a Tundra but here is an add on
https://www.powerbrakeservice.net/hybrsyfor20t.html

 

This is true. It is ridiculous. I gasped out loud when I first saw it listed.

Does the reversing and hard braking multiple times method actually work to help the rear brakes?

 

I reverse & hammer the e-brake a few times, once a week or so, and it seemed to work on one side better than the other.

 

I know it’s a known method on other vehicles. I’ve read people on here say it worked for their trucks, but I think I’ve only ever seen earlier-year guys mention it working on their trucks, but don’t remember confirmation from later years like ours. There were some rear drum changes from the earlier years to the later years, to boot. Specifically where they put the e-brake auto adjuster armature (later years it’s facing the back, hidden).