also, looks like a useful document: Error Codes TOYOTA & SELF-DIAGNOSTICS - Wiring Diagrams

That makes sense. All those codes relate to the master cylinder pressure sensor and master cylinder pressure control sensor. So you would want to test that circuit and the sensors.

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are those replaceable parts? jus,ped on a toyota part site and came up empty. bad feeling they are imbedded in the master cylinder assembly.

They are inside the abs control valve/pump assembly, unfortunately. I've never rebuilt one myself but I'm sure that's an option. There could be a problem in the actual wiring/circuit outside of the abs assembly. (Short circuit, open ground, loose connector pin) That's what I would hope for. If you feel like it you can test the circuitry to make sure you're getting a signal from the pressure sensor to see if it's working or if the stop lamp circuit is out of whack.

My aplogies for not reading the entire thread but I can add something. I picked up an used unit from a buddy who owns a 100 series LC and it matches mine. The only thing that wears out, from what I can tell, is the motor brushes and bearing. The motor is constantly pressurizing the brake system so it makes sense that those two items would wear out. I suppose the solenoid valve is also an wear item but they're not operating on a continuous duty cycle. Besides, they're just stupid on/off valves which aren't typically known to fail. Perhaps a piece of debris in the brake fluid would prevent a valve from closing shut completely but that's a stretch.

I took apart the spare unit and noticed the brushes weren't that worn down. You might recall that the motor sits vertically and the bearing that sits at the bottom had way more crud fell on top of it. Someday, I may replace both bearings and brushes, clean up the commutator then put it back on the shelf as a spare but good unit.

I'm disappointed that I didn't more pics but I have a pic of the actual motor shaft bearing for future reference.

I guess the moral of the story is if you have your spare motor, take it apart and see what's up. The chances of an electronic part like an ECU going bad is close to zero. Toyota simply makes robust parts that lives a long time.

I hope this helps!

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This is a VERY interesting statement. While I was wheeling with my daughter who was behind me, she did say that the brake lights were coming on when ATRAC was doing its thing. I asked her on the radio if they were coming on and she confirmed it.

Now I know how the system knew when to activate the rear brake lights.

Thank you for this!

so, if you are a betting man, it sounds like you would put your money on needing to replace the complete unit (master cylinder/module), which is what was done at 111k miles with a used unit w/85k? that would put me back to the beginning, and basically back to the dealer diagnostic of abs module failure. the module being $800 and the whole unit being $1200, they say they typically just replace the whole thing.

that puts me back to hunting for a low mileage unit that either an independent or dealer would install (i've had luck labor matching). looking at $700-$800.

Yeah, it sucks bud, that vicious cycle. I don't know anything about dealing with a mechanic or labor costs.. after confirming it's 100% not something simple in the circuitry it's a tough call for you.

well, i'm no worse off in a way. the issue is not affecting my drivability. but needs to be fixed. i'll shop for a good used unit first. there may be some decent resale value in mine to offset that expense.

good news, i don't have a car payment, so that saves $3-400/month.

need new tires, pre-mature wear. called the place i purchased from (discount tire direct). they, without question, helped me achieve a nearly $100/tire credit, so ordered new set for $400. so that saves some $$.

front brakes and outside CV axle on the list.

also, for the past several days the acceleration hesitation has not appeared. not sure if it has anything to do with topping off the fuel tank for the first time in a long time. thoughts on that?

Not sure if you read my reply up above but see if it's the motor that's the issue. Perhaps the brushes have worn down too much?

Anyway, I feel your frustrations amigo.

hello,

yes, i did see your contribution. i'm not sure what you are suggesting. it looks like the alternator? does this have something to do with the master cylinder unit and brake lights?

No sir, that pic is of the actual ABS motor! I took my spare one apart and made the observations I listed in the post.

Anyway, might be worth a shot!

So I was driving and all of a sudden the ABS and brake lights came on along with a high pitched alarm (my VSC trac light has also been for a minute) . I pulled off the road and when backing up so tow truck driver could pick up the vehicle the brakes got super stiff like I was driving a car from the 70s. My question is should I just have the whole ABS brake pump/motor/module replaced because it seems more like a headache to try to figure out what the individual problem is within the system?

If you can swing the expense just replace the entire unit and be done with it. I'm telling ya now, if you have never flushed the brake fluid or the fluid is dirty then the brake booster assembly is going to fail. The accumulator and it's accompanying o-ring doesn't like dirty brake fluid.

As a side note a few years ago i was getting all kinds of ABS/TRAC etc codes. I went thru every diagnostic procedure from Toyota several times over the few months and every time it all passed. I ended up replacing my brake light switch and I'll be damn I have never had the issue again. Thankfully this was on my personal vehicle and not a customers vehicle. I have replaced many of these booster assemblies over the years and i disassemble each defective unit. I always will find some type of contaminates inside the unit. There are very small passage ways that the fluid travels thru and it doesn't take much for it to get clogged. Once a part of the system gets clogged or such it wreaks havoc on that entire unit.

I have a repair shop in which 90% of my work is Toyota/Lexus vehicles. My UPS driver came to me one day and said his mom's Solara has an issue to where she will be driving it and it will just start to come to a crawl like the brakes are being applied. No pattern to when it would do it, just out of the blue. Of course this is not something you want your car to do and she got to the point that she didn't want to drive it anymore. She had taken it to several dealers and independent shops with all different kind of repairs but nothing fixed the issue. I ended up buying that car for an extremely good price as she was very frustrated with it. It was a convertible and in mint shape. I went on several test drives and finally it acted up with me. That damn thing would literally start slowing down like the brakes were being applied until it would not move at all. When my tow guy got to me it moved just fine while we loaded it up. I got back to the shop and ordered a new booster assembly and it never did it again. I sold that car and made some good money on it but I regret selling it. It would have been a great loaner car for my customers. Sorry for the long winded post but it just explains how this part will do some crazy things. The crazy part is that it never threw a code at all.