Intermittent Brake Issue, TRD Off Road

Hi everyone,

I've been reading threads for about the last 3 months trying to see if anyone has the same issue as me. I've read several threads that describe dissatisfaction with the TRD Off Road (electronic) braking system, but nothing that exactly meets mine.

Here it is:

When using the brakes fresh in the morning, they feel wonderful. Plenty of feedback at the first touch, and definitely can feel the stronger grab of the front discs as I keep pushing down.

As I start driving, I lose the initial brake feel. It feels like nothing, and I mean nothing, for the first 1/2" of brake travel, then all the sudden I can feel a stiffening, and BAM the fronts seem to bite very hard and stop me way sooner and more sudden then I'd like.

Interestingly, this winter, as I've needed ABS (skidding out in my driveway), that initial pedal response seems to come back. Like it stiffens back up. Also after using cruise control for a while on hilly highways, the stiffness comes back (I suppose the computer operating the brakes on downhills has something to do with it.

Gradually, that brake feel goes away and I end up dealing with the "nothing then BAM" brakes again.

I do feel like my truck struggles to accelerate as the day (commute) goes on. Fresh in the morning it feels like it's much quicker.

My truck is a 2013 TRD Off Road 4x4 with 54k miles. I'm the second owner, purchased in Aug 2018.

Please let me know if you have any ideas. I've had a dealer and independent mech tell me everything is fine. I have no idea if they did anything more than a test drive.

Thanks

 

Are your calipers rusty? Last time brake pads we're changed? I've had to clean up my calipers a couple times. Rust can make the pads stick.

 

Yup, make sure things are free moving up front and things are adjusted properly out back.

Do yourself a favor. With the key out of the ignition, Pull as much old brake fluid out of the master cylinder as you can (but not to the point of air at the inlet of the master cylinder), and replace with fresh Dot 3.

With the key out of the ignition, depress the brake pedal multiple times to deplete the stored pressure in the master cylinder accumulator (being an 09+ TRD OR 4x4 you have an electric boosted master cylinder). You will feel the pedal completely change feel once the pressure is depleted.

Turn your key on but dont start the truck, you will hear the pump in the master cylinder run for 20ish seconds. Let it run till it stops. Turn the key off and take it out. Repeat the step above a time or two more. This will move a good amount of fluid through the master cylinder and flush out anything causing issues.

With the key out of the ignition, and pressure depleted again, pull a front wheel. Use a piece of wood to wedge between the pedal and front seat to keep the pedal depressed good (this is to make it so fluid cant flow back up to the master cylinder). Pop a tube on the bleeder for the front caliper. get some channel locks / big pliers that will work to grab the ears of the pads. Crack the bleeder and grab the pad on one side and compress the pistons to push old fluid out of that side of the caliper (i start with the side closest to the bleeder), Keep holding the pad compressed with the pliers and close the bleeder. Get back in the seat still with the key off and slowly pump the brakes till it gets hard again (to push the pad back against the rotor). Replace the piece of wood to hold the pedal down. Repeat the process for the other pad / pistons on that side.

Do the same process with the other caliper and during all this make sure you keep an eye on fluid level, top off when necessary.

With both tires still off the truck, and pedal pumped so that pads are back in contact with the rotor turn the truck on (no need to start) and let the accumulator build pressure. Top off fluid. Leave the keys on, and replace your piece of wood to depress the pedal.

Go and crack one of the bleeders that you have a tube / catch can on. Watch out, fluid will foceably start coming out due to the electric boosted master. WATCH FLUID LEVEL in the rez. Just do this long enough to flush the lines. Repeat for the other side.


BOOM, you have successfully completed a front brake fluid flush by yourself on your truck.

 

OK, thanks for that information. I definitely plan on getting to that when the weather improves. Does anyone have any good advice or rules of thumb to check for caliper or rear brake "sticking" without getting into bleeding just yet?

I'm thinking when I rotate my tires, there might be some good checks to perform.

I can see that I have pad material on the front and sorta smooth rotors (I'm certainly inexperienced).

I'd love to be able to refine the problem in small steps, steadily getting more familiar with what's right/wrong.

 

Instead of the whole process listed above, you can do just a push of the pistons in (after depleted the pressure in the accumulator, put a piece of wood to hold the brakes, crack the bleeder and push the pistons in via the pad, hold the pad tight and close the bleeder, pump brakes to push pistons back out, repeat for other pad) You wont need much brake fluid but doing a full cycle of the pistons will free things up for sure. Just make sure you use someone or something to hold the brake pedal down, you DO NOT want to allow fluid to flow back up to the master cylinder.


Also note, because you have the electric boosted master cylinder it can feel grabby like you are describing, depending on where the accumulator is at for pressure it can bite hard when you start pushing the pedal then all of the sudden it goes, shit i need more pressure and the pump kicks in.

 

Gotcha, thanks. I suppose that might explain why, in a single drive, the upper feel of the pedal is different. The accumulator may be at it's "bottom." And the pump will kick back in and make it stiff again.

Have you noticed different feeling, particularly at the initial touch of the brake, throughout a single drive?

I would certainly say, after repeated braking (traffic), make brake feel is really bad.

Also, just for a note, I have not gotten any codes at all.

I wonder if my pump/accumulator might be faulty.

 

There is definitely times of different pedal feel for sure. But nothing drastic.

OP do you use your parking brake?

 

Yes, I do use my parking brake. I push it down as hard as I can each park.

It seems to release OK. I haven't had issue being stuck or anything.

If anything, I think my braking and acceleration first thing in the morning are best.

 

If you do a full fluid flush, make sure you keep the level high in the MC. You don’t want to mess w air in the ABS system. There’s a recent resurrection of a thread here where air in the ABS system was the culprit. Specific procedures needed to resolve.

https://www.tacomaworld.com/threads/911-brake-gurus-needed.498289/

 

acceleration makes sense, nothing is heat soaked after a day of driving or sitting in the sun.

 

Did you find a resolution to your problem len i an having a similar issues on my 2012 tacoma offroad but mine is intermittent and feels like brakes are not releasing/drag slow acceleration and when i get out and put a temp gun to the front brakes there hot 150-190deg sometimes hotter. All parts are brand new brake rotors,calipers, and pads and stainless brake lines from wheelers, im at a loss of what it could be. Sometimes its perfect for multiple days other times it is worse..

 

I never got a real resolution to the issue, unfortunately. I believe it was functioning correctly, but was just an unfortunate symptom of the computer's programming. I believe the truck needs you to romp on it alot more to behave well. I hated that. I actually sold it and bought a 2021 manual. It was a good truck, I just got fed up with the programming. Thankfully, it held it's value incredibly well.

Sorry I'm not more help. As far as the brake temperatures, I don't know what is normal, but 190F doesn't seem hot at all. Steel doesn't start getting blue until much higher temperatures, so I'd imagine that temp is normal. I'll let others chime in.

 

Yea im at a loss to the issue as well… just have to much money into my truxk to get rid of it…

 

Do you have the hydraulic boost control for the brakes that is found on the TRD off road (or ATRAC) or the more typical vacuum assist found on other 4WD models?

 

I have the atrac hydraulic boost control and have no experience with these at all

 

Funny thing. I have a '14 and am also having issues. I am getting an occasional C1452 code when scanned with Techstream. That code indicates the accumulator pressure is low. But it does not trigger a MIL. The Data List in Techstream seems to always show the accumulator pressure being near the lower end of the acceptable range.
C1452-1.pdf

Diagnosis of the code takes me to the master cylinder solenoid, a particularly expensive part rather than the accumulator itself.

The '12 - '15 models are using a hodge-podge of part numbers for all that hydraulic boost stuff: the differences being a partial mid-'12 change, truck being manual or automatic, and factory tow package.

 

Funny because i get that code randomly with techstream as well and never throws mil either. Ill see what i can maybe find out about that code as well just kind of brushed it off figured it threw rhe code when i was messing with beake pedal checking the booster and what not

 

Follow the procedure I posted and then check the data list while in tech stream and see what the accumulator pressure is doing. Mine likes to be around about 3.54v to 3.6v, and as you see from that procedure, those are at the lower most part of the range from the "normal" of 3.58v - 5v. So you see mine sometimes dips below the lower end of normal.

I'm working on the idea that something is indeed not normal. As you can see, the diagnosis of that code leads to them stating to replace the solenoid.

 

Hey thanks i will check that out tonight or tomorrow and see what my accumulator pressures are and may give us a better idea… Also where is this solenoid located anyway?

 

Its attached to the LH side (driver's) of that big booster assembly, down low, and has some 30+ wires feeding into it.

It generally has a black plastic cover and the word Advics along with a 10-digit Toyota-looking part number; it is not a retail spare-part number though but appears to be for assembly to certain models during manufacture. It is actually the ECU that is a combination of the brake ECU and some sensors for fluid pressure.

There supposedly were noted failures on 4Runners and Sequoias at one time and I am hoping that the numerous part numbers appearing from 2012-15 are not some indication of reliability as the component costs are simply ghastly.