Need advice: Brake, (!), ABS, VSC lights on

Would appreciate some advice from the community on this.

2006 Prius (package #7)
190,886 miles

At the beginning of December, our Prius had been sitting around a lot due to COVID. Got in the car to move it and 4 warning lights on the dashboard lit up: BRAKE, (!), ABS, and VSC. Using my BlueDriver OBD scanner, there were 2 codes: P3102 Transmission control ECU malfunction and P2799 Immobiliser malfunction. Odometer was at 190,700.

There was no other unusual behavior while driving it, including brakes feeling normal, except a few days prior there was a high pitched beep that warbled a bit. This reminded me of the last time my 12V battery got low, when I got a warbled high pitched beep and a bunch of codes on the OBD scanner.

However, I replaced the battery in March 2020 at 186,300 miles, so with less than 9 months on the battery, I didn't think it should have gone bad, even though the car's been sitting a lot. Measured the 12V battery in the trunk directly — it was 12.23V at rest, 11.8V in ready mode, 11.1V under load, 14.0V with ignition on.

Just to be sure, I removed the battery from the car and charged/reconditioned it with a battery desulfator/conditioner for 3 days. It went from 12.4V to 13.1V at rest.

I reinstalled the 12V battery. Scanned again with BlueDriver, and there were no codes. The 4 warning lights were still on. The inverter pump appears to be working, as fluid was moving in the reservoir.

I jumped wires on the OBD plug to show diagnostics and got the following readouts from the blinking lights:
(!): 57, 69
ABS: 42
VSC: 45

Since the brakes felt normal, I was hoping this wasn't an indication of a brake actuator problem and just a random glitch from the 12V battery getting a bit too low. I pumped the brakes 8 times in diagnostics mode to clear the warning lights.

Drove the car another 200 miles over 3 weeks without incident. Yesterday, the 4 warning lights came back on — BRAKE, (!), ABS, and VSC. BlueDriver OBD scan shows no fault codes. 12V battery reads 12.46V at rest, 12.04V in ready mode, 11.83V under load, 14.11V with ignition on. Diagnostic mode blinking lights show the same 57, 69, 42, and 45 codes as before. When I turned on the ignition for about the 4th time today, the car made that high pitched beeping sound again. It beeped for a little while then stopped. This time it wasn't warbled though.

Brakes still feel normal, and there's no brake-related fault codes.

1) What do the 57, 69, 42, and 45 codes mean?
2) What does that high pitched beep mean?
3) Do you guys think my brake actuator is a ticking time bomb?
4) What do you guys think I should do? What else should I look into?

The interior's in good shape but the paint is pretty ugly now. Would hate to sink a lot of $$ into the car at this point. Appreciate any advice, thanks!

 

Thank you for the info, @dolj and @ChapmanF! I triple-checked my video footage and it is indeed 42 on ABS and 45 on VSC.

The ECB codes are pointing toward that cursed brake actuator. This morning, I moved the car a little bit — right after startup, the brakes required way more pedal pressure than normal for a very brief period (maybe just a couple seconds during which I pumped the brakes twice after putting in drive so the car didn't lurch forward too far). After that, the brake feel returned to normal. Combined with previous PriusChat threads, unfortunately this leads me to believe that I'll need to replace the brake actuator.

Does anyone have other symptoms or tests that I should perform? Or is this pretty clearly a brake actuator problem? Thanks!

 

Ahh... good point, thanks @ChapmanF. Now that you mention it, there have been a handful of times that I can remember over the years where I had to mash on the brakes right after starting the car and moving right away. That makes sense. I guess it makes me feel better that my brake actuator probably isn't totally garbage yet... but probably is on its way out.

Guess I need to price it all out to figure out the best course of action. Thanks again.

 

@dolj @ChapmanF or anyone else,
Do you know the part number I should look for? Is one of these part numbers a better, more recent revision?

I've found references to at least 4 part numbers:
44510-47050
04003-44647
44500-47141
44500-47090

And I found someone posted this:


Thanks so much!

 

@ChapmanF @Elektroingenieur Thanks for the great information, yeah I'm CA. I did a bunch of research on the R&R and found another PriusChat member who posted a DIY method that avoids completely removing the inverter and water pump, hopefully that can make the process easier. So, to keep costs down, I just snagged a reman unit with a warranty off eBay from a seller who has good feedback on previous listings, and will tackle the work myself. Thanks again!

 

This eBay reman part route may have been a false economy...

I spent about 8 hours today removing and replacing the brake actuator with the eBay unit. It was too dark and I was too tired to work on bleeding the brakes tonight, so I powered up the car to see what would happen. The car immediately started beeping as long as the car was on. Even if the car was off, touching the brake pedal would set off the beeping noise. Clearly it thought something was wrong with the brakes. There was no power brakes at all, it was pure manual brakes, though I haven't bled the brakes yet.

I went in diagnostic mode. In addition to the same blink codes shown above, I had two more codes:
(!) >> 54, 61

@dolj Would you be able to look up these new codes for me? Thanks so much!

I have a PDF set of the service manuals, but I can't find any table that translates blink codes into DTC codes. Are they in the service manuals somewhere?

I also found a chart of specified resistance readings. On the eBay part, I measured 1300 ohms on BM2-GND1 and BM2-BM1, and 850 ohms on BM2-MTT and BM1-MTT!! I wish I had been smart enough to take these measurements before I tore my car apart and installed the eBay part!


This makes me believe that, regardless of brake bleeding, the eBay part is no good, since those readings are way out of spec. Which would mean that I'll have to find another replacement part and R&R the actuator yet again. And seek a refund.

After a couple of R&Rs, paying for a new part looks better and better.

dolj @ChapmanF @Elektroingenieur If you guys have any thoughts, I'd appreciate it!

BTW, my OEM part was 44510-47050, as was the eBay replacement.

@LaCajun 25 The worst part of the job is removing the actuator. It's a big, heavy part on a large bracket with a heavy weight hanging off the bottom, and you have to yank it out of a tight space in the back of the engine compartment. You can't get good leverage, so your body and arms are stretched out trying to deal with it. Getting it back in is easier than removing it, but getting it back on the threaded studs was difficult. It took 8 hours today, I think I can do it faster the 2nd time around. But I'm not happy about it!

 

Thanks @ChapmanF !! I didn't realize the slash number is the blink code! I searched for <slash>blink code and found these entries in addition to my previous codes. The manual also lists INF codes, but I'm not sure how to pull those codes (I don't have Techstream).

ETA: I found /42 and /45 in the 2nd gen manuals. /42 shows up twice:

	Warning Light	System	Blink Code	DTC	Fortune Cookie Message	Trouble Area
1	(!)	ECB	57	C1256	Accumulator Low Pressure	Brake actuator assembly (accumulator pressure; accumulator pressure sensor; pump motor)
2	(!)	ECB	69	C1391	Accumulator Leak Malfunction	Fluid leakage Brake actuator assembly
3	ABS	-	42	N/A
4	VSC	-	45	N/A

	Blink code	DTC code	Description	Trouble Area
1	54	C1365	Accumulator Pressure Sensor Malfunction	Brake actuator assembly (accumulator pressure sensor) Skid control ECU
2	61	C1364	Wheel Cylinder Pressure Sensor Malfunction	Brake actuator assembly Skid control ECU Harness and connector

 

Thanks @ChapmanF. I edited my last post, as I found /42 and /45 in the 2nd gen manuals. /42 shows up twice! Not sure about those entries. The actuator-related ones seem the most pressing.

Good point about the pressure sensor readings.

What do you think about the resistance readings on the eBay actuator's connector pins? That would suggest that Toyota immediately deems the part "No Go."

I measured the resistance on my original part, and all are within spec (about 1 ohm) except the MTT readings, which are 500 ohms (spec is 33 ohms).

 

@ChapmanF Ahhh!! Thanks for catching my mistake. I didn’t notice/realize that the codes are categorized in that fashion. That makes sense. I’ll go back and fix my table.

Actually, I’ll need to double check if I picked up the correct DTC for the two new blink codes too.

 

Looping back on my thread with an update...

I ended up returning the eBay "refurb" unit, but I didn't have another replacement part to put in. So I R&R the original brake actuator. Since I knew I would have to R&R it yet again, I removed the big heavy damper from the bottom of the actuator. That made it so much easier to reinstall the actuator. It took less than 4 hours this time. For S&Gs, I tried to do a quick Techstream-less brake bleed to see if I could temporarily drive the car around with the original actuator. Nope... it didn't work, the brake system was completely whacko.

I eventually decided to just buy a brand new brake actuator. It came with a matching resistor. My son helped me install it; his skinny long arms allowed him to R&R the resistor from the driver's footwell without having to remove the entire instrument panel. The mechanical portion of the job of replacing the parts took about 4 hours, and getting the actuator in and out (even with the damper installed) was definitely easier with 2 people.

However, the rest of the job was even more time-consuming. I figured since I bought a new actuator, I might as well do things the right way. So I got a Techstream compatible cable off Amazon and installed an old version of Techstream in a VM (using this awesome DIY that even includes a VM image: How-To: TechStream In 5 Minutes | IH8MUD Forum). I followed the service manual, doing a zero down procedure before removing the actuator, then the full brake bleed process afterwards.

I kept having failure screens popping up in the middle of the Techstream brake bleed procedure. The car started acting strange too, with messages about transmission problems and not going into Park. I kept trying over and over, with failures always cutting it short. Eventually, I realized that the 12V battery had drained too low while working on the car, which was seemingly causing the problems.

I gave up for the night, and recharged my 12V battery over the next several days.

Today, we tried again. To be extra sure, I also connected a second 12V battery from one of my other cars, and attached a Battery Tender for good measure as well. Even then, the battery drew down from 12.9V to 12.2V from beginning to end.

It worked though, with Techstream successfully completing the brake actuator replacement bleeding procedure (which is quite long and consumes a lot of brake fluid).

But then I needed to initialize the brake system. This ended up requiring me to repeat the process (Linear Valve Offset) 4 times, including yanking the battery to reset the vehicle, before it finally succeeded.

Brakes finally are back to normal! Success!

Unfortunately, this managed to lose the yaw control/deceleration sensor zero point calibration, so there's a VSC code (C1336). However, I found the procedure to reset the zero point in the Service Manual, which requires a level surface and Techstream yet again. Perhaps it got thrown off because my driveway has a sizable slope. Either way, I'll find a flat lot and reprogram the zero point, then I should be done!

Thanks all for the help!