Greetings, My 2004 XC90 2.4T AWD (244K miles) has a problem with the ABS. It activates when not necessary. I am told it's about $800 to fix by my indy mechanic. We tried pulling the fuse for ABS (#14 30amp), and the "brake system failure" warning was on. In addition, the odometer stopped working, so we need another solution.

I am trying to see if I can deactivate the ABS system (essentially drive the car with no ABS, which is fine with me) but without deactivating the odometer. We are trying to avoid putting money into the car unless it's absolutely necessary; it's probably on its last legs.

Does anyone know how we might do this?

For light money, you could

1. look at the wiring to the sensors at the wheels (I had a '90 744 TI that had wide wheels and one of the wires to the front wheels had a rub spot on it - I was able to move the wire through its mounting to bring it away from the wheel

2. Check the rings that the sensors use - they can get gunked up or deteriorated so that they do not work correctly.

3. Reset the computer in your car by disconnecting the battery for 10 minutes or so. I had a problem that caused my 2008 XC 70 to lock me out because I did not correct a low tire pressure. I had to use my emergency key to get into the car. My dealer, Volvo of North America, and this board had never heard of this problem. My son-in-law's father suggested that I disconnect the battery - issue cured!

My son-in law suggested that the wireless computer in Subarus ran both the tire sensors and the remote key!

Hi Kcookvt,

You don't want to be playing games with your brakes.

Please elaborate what the symptoms are, and what your mechanic wants to do for $800.

Do you get OBD codes for the brakes?
Go to any chain auto parts store and let them read your codes and post back.

Bill

Thank you for your reply. Basically, the issue is that the ABS system seems to kick in when not needed. That is, the brakes pulsate as though ABS is activated even during normal stopping. I am not sure whether that is dangerous, but I agree that it's not something to mess with.

My mechanic, an indy Volvo mechanic I trust completely, indicated that the simple solution was to disengage the ABS. He tried this by removing the fuse for the ABS, which means the car drives with no ABS. That would be fine (though the "brake failure" light would remain on, which is a little unnerving). However, removing this fuse also disengaged/disable the odometer, so we need another solution.

I asked what the alternative was, but this was at the end of the day Friday, when he was trying to wrap up his work for the holiday, and before we knew that the odometer wasn't working. The context of the question was basically "what if my wife would rather fix the ABS than drive a car without it?" His response that it would be about $800 to repair, but he did not specify why, as we both believed at that moment that we would not be interested in fixing it for that price.

The car has some rusting that makes this the last year the mechanic will allow it to pass inspection. Again, it runs well and is reliable, but the fact that it can't be inspected again makes us wish to avoid further expenses to the degree we can. If it is unsafe to drive, I imagine we would spend the money to fix it, as it would get us a year of use.

Hi Kevin, If I remember right, you posted an 850 before.

Go get those OBD codes and see what the ECU's tell us.

Rust? Did Volvo forget to galvanize your body parts?
Find another inspection station, one that doesn't sell cars, and
see if they're so pessimistic about your car passing inspection.

Bill

Hi Bill,

Thanks. I have posted about XC70 (we have three) and V70/V70AWD (we had/have one of each) along with XC90, but no 850. Volvo for life, or until rusty.

Yes, here in Vermont, they eventually rust.

Hi,

I have tried to follow you on the ABS problem just in case my 240 cars develop an issue like yours.

I think Bill has given you some good ideas about getting codes. I wonder if it can be specific?

Your car at least gives them. I’m not aware that the 240s are that sophisticated.
My cars are just past getting into the ABS but way ahead of the Flintstone mobile using the foot in the shoes for brakes.

I recently rented a Nissan Frontier truck (the cheapest vehicle they had for $400 week of driving) that probably had that ABS whistle installed but I never felt them engage.
On my 240s you must have to hammer the brakes to get them to work.

So I realize now how this similarity that you say is unnerving!

What I did feel was the engine to stop running at traffic lights. Trust me I thought I had gotten a defective rental seeing a feeling the engine shutter on take offs.
It took me a few times to realize it was the pressure applied to the brake pedal or the repetitive releasing of the brake that would keep the engine running.

So, in all of the dramatic lead up, I think you have only a bad sensor in the master cylinder system or at least one that is maladjusted on the brake pedal below.

I know not much of anything about ABS, my disclaimer!
There has to be a signal created to make the system start to work and how much.
Past that, it’s about wheel speed sensors getting dirty, of which is the first boogie boo, introduced by natural causes.

It’s interesting enough to note another phenomenon and it’s that $800 fee!
That was the same amount quoted to fix my sister-laws ABS light on a Range Rover, SHE HAD!

It appears to me that any vehicle past ten years old or 175K miles gets a “trade it in for new certification” from mechanics or dealerships as they do not want to deal with any liabilities.

Brakes are supposed to be well engineered to not fail and in so should be very reliable.
I too think $800 is ridiculous as that is about all that the car manufacturers pay for the whole system from vendors with patents cost included.
Remember the interval windshield wiper or the push button ratchet scandals?

The sentiment about rusted vehicles is another concern as todays cars are so “unbodied” (snapped together or use adhesives) that the labor cost for a “person” to fix them, makes a hand built roadster or an older 240 more valuable. IMHO.
Young people that are capable of using more than their thumbs will need more time consumer projects, like yours, to make up reasons to be scratching their heads.
Do you know some brilliant ones?

Is your ride getting run down a whole lot as having these kind of issues are what makes people get all starry eyed on dealership showroom floors.
I hear New Car Fever coming your way and the adages of taking two aspirins and sleeping it off may not work!

Phil

Hi Phil,

There's a bunch of Diagnostic Trouble Codes (DTC's) for 700/900 ABS at port A3.
Dunno about late model 240's. Maybe they have just Fuel and Ignition? A2 & A6.

I'm in agreement with you that new car fever is raging in VT.

Happy Thanksgiving & don't eat too much...no gobbling!

Bill