ABS module failure bad brake fluid

So I have an 07 hyundai Tucson with
about 60,000 miles on it. The other day
my ABS module failed and locked up my
brakes. This was a diagonal brake failure.
I took it to the dealer the next day and
they assessed that the ABS module had
failed due to bad brake fluid. There was
also a leak in the rear of the master cylinder.
They quoted me an entire brake system
overhaul including the ABS modules.
This was not what I wanted to hear.
The BIG problem is that 9 days prior
to this brake failure I had brought my
car in to the local mechanic to do an
inspection. I was experiencing sideways
pulling at high speeds. They did their
inspection and were unable to replicate
the issue. They said they visually checked
the brake fluid stating it looked good an
was at the appropriate level. They took
a picture from the side of the resevoir
but not of the brake fluid color.
In the picture of the resevoir the fluid
looks darker than it should. They gave a
report stating that the car was in great
shape and needed only a minor alignment
adjustment. I had the work done and
9 days later my brakes locked up.

What do I do?

Pay to have the brake system repaired.

Since the advent of ABS, brake fluid service on a recommended schedule is far cheaper than rebuilding the brake system.


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and find a new mechanic.

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They quoted me 4,900 to do the whole thing. That’s about what the car is worth now.

Brake fluid is tested for the amount of water in it with a tool. A tool your mechanic did not have. A cheap tool, actually. Less than $50.

A visual inspection is not enough.

Sorry, but brake fluid should be changed when the moisture level hits 3%. That takes about 3 years depending on where you live.


but he took a pretty picture. LOL

Yeah I contacted the customer service for the mechanic. I just want to determine whether the inspection I paid for includes testing the brake fluid or just looking at it.

It really won’t matter. The damage was done long ago. No mechanic can see the neglect inside your brake system.

So… they check my brake fluid. 9 days later its brown and has worked it’s way through the system. You’re saying they wouldn’t have known that when checking the brake fluid?

I am saying the damage was done long before they did any checking. And any checking they did would not uncover damage done from old wet brake fluid corroding the INside of the ABS unit. When the seal come apart internally, it makes a mess, internally and colors the fluid.

I think I understand now. Thanks a bunch for your help.

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It is pretty hard to tell just by looking at it . Brake fluid always looks dark inside the reservoir .

I’m not a car person. Everything I know about them was pretty much learned yesterday via hours of research. It just seems to me that when a multi point inspection claims to cover brakes, that should include the very simple, quick, and inexpensive test of the brake fluid. I mean… it seems kind of messed up if that’s not a standard in the industry.

What’s important isn’t how much the vehicle is worth on the open market. What’s important is how much it will cost to repair versus the alternative, which would be to junk it and buy something else. Obviously, you can get a different vehicle which runs for less than $5k, however you should be able to find a different shop which will do this repair for less than half the dealer’s quote.

Alternatively, you could purchase a remanufactured ABS module for your vehicle, or have the existing one rebuilt, and then take it somewhere to have the remaining brake work done if DIY is not an option. For example, here is a website which offers the service of rebuilding ABS modules, and specifically mentions your vehicle:


If you do get it fixed I suggest you also get the transmission fluid changed, not flushed, and every 30-60,000 miles going forward.
Trans and brake fluid are two things the car makers often don’t talk about maintaining, but should be changed periodically for long trouble free life.


You also don’t have to get these repairs done at a dealer. It’d be a lot cheaper at an independent shop.

If anyone ever tells you never get a transmission flushed, don’t listen to them.

Here’s why.


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Update: most commercial mechanics won’t do the ABS if I have it rebuilt. However, I can get it rebuilt and for a very reasonable price. Master cylinder is getting replaced along with the brake fluid flushed. I decided to take all your advice on the transmission fluid though it won’t be a flush due to the year of the car and the fact that the solvent used in the flush can be detrimental to the seals. Hopefully this solves my issues.

Wise move.

Rebuilt abs unit, new MC, brake fluid flush. Sounds like a plan.