2004 xc70 front hub ABS

[aPpYe]

2004 Volvo XC70 Automatic ...

About a month ago, I bought this vehicle and replaced the right-front cv shaft and hub/wheel bearing assemblies. About a week (and perhaps 400 miles) later, I was getting the ABS light, the little orange triangle with an exclamation point in the middle, and a message about ABS and anti-skid system. I don’t remember the exact verbiage of the message, as I don’t have the car with me at the moment. I also noticed some pulsing and grabbing of the brakes at low speeds, especially when coming to a stop. The AWD system would also come on and off, mostly during hard turns at low speed. I pulled the wheel and found the center axle bolt had backed completely out. Either I did not torque it at all or did not torque it enough. I torqued it down nice and tight with some thread locker, and cleaned a small amount of soot and grease from the sensor. I reassembled it and the symptoms went away. All was good the dash had no warnings...

A week later, the same exact symptoms showed up. I pulled the wheel again. This time, I double checked that the bolt was tight, which it was. I tightened it a little more for good measure. I pulled the sensor again and blew out everything in and even remotely around the hub with compressed air until no more dust came away. I then sprayed some brake cleaner down into the sensor hole while rotating the hub to make sure the nibs that the sensor are supposed to see were squeaky clean. I reassembled and all the issues went away.

Another week later, the same symptoms came right back. This time I made sure to get a brand new axle bolt from Volvo (p/n 30640878) and torqued it to spec, 35Nm plus 90 degrees. I did not pull the wheel or the sensor this time. I drove the car and everything went away again, but only for about fifteen minutes before the symptoms reappeared, same AWD thing coming up, same occasional grab/pulse of the breaks when coming to a stop, same lights and the same warning on the dashboard.

Besides having a weekly ritual of wiping down the sensor, does anyone have any ideas on what I can do here? I am completely out of ideas ...

[Xfingers]

Something you can quickly check...Are all 4 of your tires the same brand, the same size, with an equal amount of tread wear? I'm not sure if it's as much of a factor with the MY04-07XCs, but apparently with the 2001-02, the pre-Haldex AWD system is sensitive to differences in tread wear. The owner's manual warns that damage to the AWD can result.

What you're really gonna have to do is get the codes read, preferably using Volvo VIDA/DiCE diagnostic software running on a laptop and hooked into your car's OBDII port. You can find a lot of info on this site and the internet if you search. The software is a bit cumbersome to install and use.
This worked for me: https://forums.swedespeed.com/showth...-Download-Link
General info: https://forums.swedespeed.com/forumd...ine-Management

Or you can go to the Volvo dealership or a good independent Volvo shop and have the codes read for $$.

[Astro14]

Correlation is not causality...

So, while your axle bolt may have loosened twice, your problem may be elsewhere in the system, for example, an ABS controller or, perhaps CEM fault, or just the sensor itself.

Time to hook it up to VIDA and start looking at what the car sees, not what you see...

[aPpYe]

same tires and wear level all around... I will check tire pressures. It is odd that cleaning off the sensor fixed it twice for a solid week each time. I will drive the car for the afternoon before doing it again, just to make sure the system continues to complain with the new bolt in place before pulling the sensor and wiping it off again...

I will also look into the VIDA/DiCE thing ... It is nice to see that the software is freely available in that post you linked. I have not thoroughly read through the links, but I am assuming the hardware to plug into the car is not free ...

[Xfingers]

The DiCE unit can be found on Ebay for around $100. There are many vendors. If you order from China, it'll take longer to receive it.

[billr99]

If the sensor is the original, I'm betting the sensor. I had somewhat similar circumstances a few months ago on my XC and a new sensor sorted it. But with that said, I also had VIDA to pinpoint the issue. Interestingly, it appeared that a small pebble had gotten caught in the teeth of the tone ring which then proceeded to wear or break off the end of the sensor. Sensor's resistance was the same as a new one so I concluded that the ABS error came as a result of two much gap between the ring and the sensor. Weird deal though.

Cheers,

Bill

[nickbw]

Yes, I know this is an old thread but I thought it might be helpful to know that if you have a Memo Scanner U380 car diagnostic tool (which is quite cheap) it will both read and clear ABS faults and is much less of an effort than making a working Vida/Dice system, plugging it in and navigating the not very clear software interface.
You may find that it takes multiple attempts for the fault code to actually clear. It always takes a second attempt for me before it works.

[vtl]

Check the ABS tone ring on your new axle. Is the axle Volvo/GKN or aftermarket?

[nickbw]

look under the hood and find the sensor wire coming up from the hub into a position near the fire wall. There are wiring harness on both sides at this point (inside plastic covers) and there will be a connector attached. No need to detach from harness cover (easily broken) but unplug (small latch button to depress) and use a multi-meter to read the resistance. Set to lowest value on Ohms scale. Then move to the other side of the car and do the same. This will confirm the sensor is good if you get the same reading from both sensors ( i get 62-63ohms) and indicates to need to remove the road wheel, brake disk, brake caliper, disconnect the steering knuckle and ball joint. Push the drive shaft/hub and inspect the tone ring. Clean off the CV joint after removing tone ring. Heat up new ring in oven, then fit making sure it is uniformly seated (use old ring to drift it). Remove 10msor to m bolt holding wheel sensor to bearing carrier USE penetrating fluid and a small wooden drift from below to ease out the sensor. Clean out its seating with brake cleaner and the sensor itself so that it seats properly in close proximity to the tone ring. These cost under £14 including delivery in the UK. After reassembly take the car for a short run to test no ABS warning returns.