Intermittent Brake Issue, TRD Off Road

Hhhhmmm probably no way around it but buy one huh? You would think that there would some type of better test to diagnose it or something

 

Yeah, but that test procedure for the code does not suggest an alternative. If it were just the accumulator that thing new shows for about $260ish but we as consumers do not have the luxury of just part swapping. I would feel much better if a hard code were set. That solenoid alone is $1+k through a discounter, and all the guts complete for a DIY around $1850ish from a discounter.

@Bishop84

I swapped a couple of PMs with you awhile back about the diagnosis for brake Code C1452 on a TRD OR. You stated that you had replaced a few of the solenoids. Question for you is was a hard code ever set or was the code transient?

 

I had this same feeling on my 2015 OR. I actually used to get a hissing sound while braking that was a little weird....reminded me of the air brakes on my last MRAP.

The only way I got rid of it was to have a buddy properly adjust the rear brakes (I don't know why but he said he needed to start with that), replace the calipers (they weren't leaking....but they weren't applying even pressure and the pads had really uneven wear), and then bled the whole system with the actual toyota tool. The end result is my brakes are great. While we were there we replaced the OEM brake lines with new OEM lines....because why not.

He used to work at a toyota dealer and had his own shop....not anymore thanks to Covid. I need to catch up with him and see what shop he went to....

 

In trying to research this issue I ran across that "hissing" sound described in other forums several times that seemed to be some type of precursor to issues. Not sure of the fixes because way too many do not follow up with any final resolutions

 

The hissing in my truck seems to have almost gone away completely so I am going to attribute it to air in the lines. To be honest I wish the brakes were like the last Chevy Colorado I rented....but thats about all from that truck I wanted.

 

hey really appreciate the tips and knowledge i dont have any experience with these power brakes ateac systems but i followed the procedure last night at my Accumulator pressure sensor was sitting at 3.4-3.5v this morning on my way to work it was between 3.5-3.7v at around 70ish mph

 

Hey TW. Hopping on this thread and forgive me if I am hijacking it but I thought it better to ask in this thread instead of starting a new one. Current system is working just fine. Going to be replacing front pads and rotors real soon and want to do a simple bleed just for fluid change. I have soul-searched through threads (see below) and the answer is still not clear. Can I simply bleed my brakes like any other normal vehicle or do I have to go through this oddball hold the "pedal down and depress the pad" gyrations?

The DIY thread below kicks me to ToyotaNation and I read that thread. It made sense but then the followup thread banter made it sound like it was a different operation for the TRD OffRoad. Someone school me please!

https://www.tacomaworld.com/threads/2nd-gen-diy-maintenance-quick-reference-guide.438945/

https://www.tacomaworld.com/threads/brake-bleed-question-advice.713661/

https://www.tacomaworld.com/threads/pressure-bleed-brakes-with-vsc.355367/

 

I just did this on my 2012 TRD-OR. For the rear, simply hold the brake pedal down but on the fronts you'll need to pump the brake.

 

Hmm. Those values seem to be low or beneath the minimum per normal range like mine. Have you let it sit for a while, even overnight, and checked without starting and driving to see the pressure displayed?

 

Alrighty. I will give it a try. What's the worst that can happen?

 

Ill do it in the morning before work and see… last night i reset by removing negative cable gor a couple hrs then monitored the accumulator sensor was around 3.8v and no drag feeling what so ever. But im sure it wont last long usually doesnt

 

While you are in the Data List, take a peek at one more pressure on that same Data List. There is another pressure related to the same Master Cylinder Solenoid that I am also keeping an eye on. It is the Master Cylinder Pressure.

0410051.pdf

This relates to a code but see on Page BC-210, the second page, midway in part 2 is the test procedure for the Master Cylinder Pressure. On the same Data List of my Techstream it is listed as MAS CTL PRS 1.
The Normal Range is supposed to be 0.3v to 1.9v for a leg pressure of 11 ft.lbs. I just kind of guess the pressure of my leg pushing on the pedal and watch the value change.

 

I wanted to chime back in with two things:

- I did have a "hiss" when starting to apply brakes on my 2013 TRDOR automatic (I bought used with 40k miles)
- My 2021 TRDOR manual has the same braking system and is alot better (go figure), so I imagine some improvement can be made with rear brake adjustment and brake bleeding

My issue could have been just simply "less than stellar" braking and in need of some sprucing.

 

Alright so this morning did the procedure before starting and when i keyed on and pulled up techstream accumulator pressure was 3.54v i watched it drop slowly until it stopped at 3.33v truck off not running master cylinder sensor pedal not being touched is .49v depressing around 11ftlb id say around .8v give or take… started truck and accumulator sensor jumped up to 3.52v still little low but really confusing this sucks lol..

 

I see the OP visited again and commented on him having the "hissing" others have reported. Thank you OP!

Mine does not hiss, for the time being at least.

Did you get the C1452 Code back?

I think I will keep an eye on those those two pressures by running the exact procedures for the accumulator pressure and master cylinder pressure again. Too cold now so tomorrow.

Oh, I ordered the master cylinder/solenoid/brake fluid section (#2) of the unit. There are four basic sections:

(#1) - Entire Unit
(#2) - Master Cylinder/Fluid Reservoir/Master Cylinder Solenoid
(#3) - Master Cylinder Solenoid
(#4) - Accumulator/Pump.

Here is a rub. The Master Cylinder Solenoid itself (#3) pricing is near or above the cost for the entire #2 sub-unit. Go figure.

Part I ordered is #2

 

That seems way low. Are you following the exact procedure for C1452 doing 40+ pumps, key on/of, wait 99 seconds, etc. etc?

 

Did the following key off pumped brakes 40+ times…. Note: probably 15th time or so brake went soft/spongy like inhad depleted the accumulator but continued on stopped after 40 times foor off brake and keyed on truck waited 99seconds also connecting techstream and watching data which were the numbers i gave in my prior post… does that sound right??

 

Yes you are depleting the accumulator like you say.

I resorted to printing the thing and have to have it in hand when I do the procedure because I don't want to kick myself if I leave something obvious out. Done that before on other stuff. But its not that hard and sounds like your memory is much better than mine, ha.

I swapped a PM with a tech on this forum who has dealt with this problem. He responded by stating he has changed only 2 or 3 solenoids and the issue was usually with older 4runners and sequoias. Said it appearing after a brake job when the pedal is pressed to build up pressure again.

As for the consistently low accumulator pressures I noted, he said he thought it was giving warning signs of failure. He recommended bleeding it (again) and make sure the calipers are free and the rear drums adjusted properly.

 

Im going to give that a whirl this weekend flush old brake fluid and put new fresh fluid bleed the brakes pull the drums back off and try and find a picture of how they are set up in case maybe i put a spring on backwards or something when i did the brakes, check the front calipers and see what happens...
You happen to have a electrical schematic of the master cylinder/ accumulator sensor wiring diagram of which wire goes where and what voltages are supposed to be?

Did he say which solenoids? Wonder how that happens change brakes and now solenoid just doesnt want to work hhhhmmmm

 

1. Here is everything on the rear brakes. The files are in order of page groupings. The complete assembled diagrams for LH and RH are found on Page Br-74 of the second file.
04201010.pdf
04201.pdf
042010.pdf

2. Yes, I have the electrical for the pin outs. It will take a while to put together and so I will have to send later.

3. BTW, Have you done a zero point calibration with your TS? If not, its real easy and quick but you will need to use the TS to first erase the old calibration and then reset. Does it affect the accumulator pressure? Who knows but everything is interrelated on that unit......