Hi I'm bill. I have an '04 xc70 that I've owned since '07. Love the car. The car has about 200k km on it. My first and only volvo so far.

I do all my own maintenance. I have a vida clone system on my notebook.

So I just redid the rear brakes. All was fine. A couple of days later, I felt a slight grinding in the brakes, and the ABS light went on. I don't know if the brake job was a coincidence, or cause.

On startup, the ABS warning is off. Some meters of driving later, the traction warning light comes on briefly, and then you get the ABS light, which flashes continuously.

I got a BCM-0032 which is rear left brake mechanical error.

Because they're cheap, I replaced the rear sensor without doing much thinking about it. It was a trivial job after having disassembled the new connector and pulling it through with the old wire with the sensor snipped off.

Nothing changed. I hooked vida back up, and drove around. The sensor works, but what you see in the vida display is that the speed reading of the offending wheel drops briefly during every wheel revolution. I'm guessing it's the reluctor ring, but I understand it's in the hub.

Is replacing the hub the only option? It's only been in there a few years

Cheers!

 

The most common errors with ABS systems - is the control unit. Usually they will start giving bad wheel sensor codes. As you found out - it's not the wheel sensor. I've never replaced a reluctor ring. (or a sensor that didn't have broken wiring) Here in the south they just don't rust out - even though i've heard of ring problems in other climates.

The ABS control unit develop cracks in solder joints inside - Your ABS control unit is probably "coded" to the VIN of your car, so usually a used part won't work.

A company such as xemodex can fix yours or sell you a fixed one "coded" to your vin. And they are in CA also! Check their flow chart for ABS control units And I'm certain you have seen what comes up when you click that code in VIDA - suggesting the control unit is not the problem. (pictured below)

https://xemodex.com/us/bcm-diagnosti...-s60-s80-xc90/

https://xemodex.com/us/products-for-volvo/

 

I'm pretty sure it's a mechanical issue, since the there is a pulse drop in the speed as seen in vida, once per revolution of the wheel. No electronic fault could look like that

So I know the sensor is good.

Is the reluctor ring actually in the hub? how could it be damaged? anyone ever take one apart?

 

Must be - the front axles have a ring on them, the rears don't

 

any possibility it's in the axle shaft itself?