I'm in the same boat. Just bought an '03 V8 RWD with a known abs pump issue. I've been trying to figure out if it's the pump or accumulator that is to blame. Is there any definitive way to diagnose which is the cause of the problem? I hear my pump engaging all the time while driving around. No lights on the dash or problems with brake function.

I just wonder if the pump motor is weak or if the accumulator is not holding the pressure. I've been looking at a reman pump on ebay, but don't want to pull the trigger if it ends up being the accumulator. I suppose the safest bet is getting a whole refurbished assembly.

Any tips for the diagnosing the culprit here?

As a small update, I actually work at a independent shop with 5-6 Toyota/Lexus master techs. I got the Toyota shop foreman to take a look at the abs pump for me this afternoon. He thinks that since my pump cycles on way more often than it should even without applying the brakes it’s likely the accumulator isn’t holding pressure well anymore.

Before asking his opinion, I was going back and forth in my mind about getting a reman pump from eBay or possibly getting the pump off and refurbishing the brushes and commutators inside. My foreman thinks we should first replace the accumulator and see if that fixes it. If it doesn’t, we’ll look at cleaning the pump.

Post updates I'm dealing with this as well

Hey guys. I have dealt with the squealing accumulator before.

Always relieve the pressure at the brake booster assy by turning off ignition and pumping the brake pedal until it go`s slack. ( about 15 pumps) . Then you can proceed with accumulator removal. Also there is a spring and accumulator tube that may or may not come out upon removal. just go slow and easy.

Before you go and spend 400 Bucks on the whole accumulator, Buy the O-ring for it from a dealer. Remove the accumulator, replace O-ring, lubricate O-ring slightly , then re install accumulator. It is so simple that it is worth it to try replacing the O-ring first.

I wound up having to replace my Accumulator, and I have not had any issues since.

By the way, I did not bleed the system afterward, and had no apparent issues.

yeah, my problem is pointing towards an accumulator leak, as if am in stop n go traffic, the pump cant keep up, and the brake alarm goes off with lights on the dash etc. keeping the car idling in park for a few minutes usually resolves the problem as the pump is able to repressurize the system..

do you have a video of this accumulator oring fix?..
whats the oring size?

the O-ring isnt really a fix, but an option to try. Never remove the accumulator without a backup O-ring. If the O- ring is damaged you will be screwed if you dont have one readily available.

O-ring Size? no, just order it from Toyota to be safe.

I think I'll replace this oring before I buy the accumulator. If the oring doesn't make a difference, I'll try the accumulator next. Last resort will be taking the pump off and seeing if the internals can be cleaned up.

My Toyota master tech here at work is putting his money on the accumulator being the problem. The pump is running way more often than it should. He believes the accumulator isn't holding pressure anymore, so the pump just continues to try and build up pressure over and over. I assume if this goes on long enough the pump motor might fail from overuse.

Keep us updated until you solve the problem, I think I will be facing this issue sooner or later.
TIA

Good news, I replaced the accumulator and o-ring and all my brake noise has gone away! My pump motor is only running occasionally like it is supposed to, and there are no more chirping noises at all. Looks like the problem was as my shop foreman deduced, the pump was working fine but the accumulator was not able to hold pressure. Fingers crossed, but I think I just fixed this with a $175 OE accumulator from partsgeek.com. The Toyota accumulator lists for $447.88 (part number 47950-30010).

Hope this helps someone else and prevents them from spending $2000+ on a new abs pump assembly from Toyota when all they need is an accumulator.

did you watch videos to help in the fix?, i believe i have a similar issue, and am a bit clueless on where to start

I had a very similar issue.

at 180K miles I started hearing feedback and chirping from under the master cylinder.

Turns out that the ABS motor connects to your hydraulic brake pump and is wearing out. (just like most motors do)

It is a simple RC type motor that can be removed from the master cylinder and replaced or you can attempt to take your abs motor apart and try to clean/ refurbish it.

I bought a refurbished ABS Motor unit from ebay and swapped it out for my old one without detaching the brake lines or removing the master cylinder. It took about 25 minutes to complete overall and cost me $250 for the replacement motor after I mailed back my burnt out core.
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2003 4.0L v6 Sport

I finally had enough of the chirping and near constant running of the p mp. I purchased a rebuilt pump and accumulator from a guy on eBay and had my buddy install it and flush the entire brake system. I had him do it cause he has a lift and techstream software to properly cycle everything and ensure a proper bleed at the accumulator. The difference is night and day. The pump is almost silent and seldom cycles unlike before. A well spent 500 bucks.

i'm new to the forum, but i've been reading the posts for some time now. I've been particularly interested in this thread, as i've have had the issue with the squeaking ABS unit for about 6 months now. The noise is intermittent and seems to be most common when the car is cold. Based on what i've researched my mechanic has tried 2 repairs to remedy this problem.

1) replaced ABS pump motor with rebuilt unit. -> Did NOT solve the issue
2) just replaced the entire actuator assembly (#47050-60081) with a refurbished unit from eBay. -> Did NOT solve the issue

Needless to say, i'm a bit frustrated and confused. Any ideas as what to try next?

btw, i have not had any warning lights or brake pedal issues to date.

03 Limited V8 4wd, 172000 miles

Not sure if anyone is still following this thread, I use the cigarette jack to charge my phone, every once in a while the ABS will engage. I unplug the charging plug and it goes away.

Could it be janky charging plugs somehow short circuiting it?

Heck I have driven a 700 mile trip with the phone charging the whole time and nothing. very random.

Looking for help here or ideas.

2003 4runner SR5 4wd

Wen to O'Rileys and the code reader showed C1210 & C1234

Wich rebuilder are you guys having good luck with?