Dear fellow gen1'ers...Our 2012 is about 6-1/2 years old now and has ~90k miles. It lives in a cold climate with salted roads. We bought new, no wrecks or suspension damage. Here is an admittedly long post on my recent experience with failed front hubs.
A few weeks ago, the passenger front ABS tone ring disintegrated. I was driving at sustained highway speeds when the car seemed to lurch slightly (it did feel like the ABS actuated momentarily) and then everything went back to normal but I got some warning chimes, a Low Traction message for moment, and then a few dashboard MILs thrown: "Service Stabilitrak", "Service Brake Assist" driver information system messages, accompanied by the ABS and Traction Control yellow lamps.
Once home I read the codes and got C1226 (passenger front, excessive wheel speed variation). I cleared them and drove the car a few hundred yards, there was significant rhythmic ABS activity on each wheel rotation until it gives up and set the codes again. Sounded like a crunching noise.
Since it was cheap, I replaced the ABS wheel sensor but that didn't help. I took it to my shop and they confirmed the passenger hub assembly ABS tone ring had failed. They replaced it.
The first attached image is what the old passenger hub assy looked like. The problem is visible as chunks missing from that brown ring...that's the tone ring, or what's left of it.
Part 2: The car was then fine for only a few days (<200 miles) until the same symptoms occurred. Once the car was back home I read the codes again, but then it was C1225 (driver front, excessive wheel speed variation). And just as before, if cleared the codes would set again once the car was driven any distance, and there was ABS activity while it determines the fault. Back to the shop where they confirmed that the driver ABS tone ring had similarly disintegrated.
The second attached image is the driver side old hub assy. In this case most of the tone ring is gone, only a small arc remains.
I am perplexed that both tone rings would fail so close in mileage/age. An errant piece of gravel is not to blame here. YonderGod mentions something very similar in https://gm-volt.com/forum/showthread.php?325299-Wheel-Speed-Sensor-DIY-repair
I wonder how many of you have had issues with the ABS/Intellitrak system due to ASB tone rings/hubs?
-russella
A note on the the symptoms and driveability of the car once these faults are detected: ABS is not active, no traction control or stability (of course). After cycling ignition, the Check Engine light will be added to the mix of other lights in the instrument cluster. Hitting the regular service brake won't use any electrical regen...only friction brakes (you do get regen in L though). If you try to use the parking brake to slow the vehicle when moving it will also turn on the the parking brake yellow warning light and set a code (I don't recall which), and parking brake stopping distance is much larger than normal. Finally there is some subtle hunting/surging that occurs at cruising speeds, especially on a slight downhill (no idea why.)
Box for the new pass hub lists GM# 1358-5466, and box for driver side lists 1350-7016.
Another note on the tone ring: My auto-component knowledge is a bit outdated so when looked down into the hole of the sensor, I was surprised not to see a toothed wheel, which I hoped to inspect or clean. The new systems use a thermo-set plastic with magnets or ferro-magnetic buttons embedded inside. https://patents.google.com/patent/US8020676 It's pretty hard to see much down the bore hole for the sensor anyway.
A few weeks ago, the passenger front ABS tone ring disintegrated. I was driving at sustained highway speeds when the car seemed to lurch slightly (it did feel like the ABS actuated momentarily) and then everything went back to normal but I got some warning chimes, a Low Traction message for moment, and then a few dashboard MILs thrown: "Service Stabilitrak", "Service Brake Assist" driver information system messages, accompanied by the ABS and Traction Control yellow lamps.
Once home I read the codes and got C1226 (passenger front, excessive wheel speed variation). I cleared them and drove the car a few hundred yards, there was significant rhythmic ABS activity on each wheel rotation until it gives up and set the codes again. Sounded like a crunching noise.
Since it was cheap, I replaced the ABS wheel sensor but that didn't help. I took it to my shop and they confirmed the passenger hub assembly ABS tone ring had failed. They replaced it.
The first attached image is what the old passenger hub assy looked like. The problem is visible as chunks missing from that brown ring...that's the tone ring, or what's left of it.
Part 2: The car was then fine for only a few days (<200 miles) until the same symptoms occurred. Once the car was back home I read the codes again, but then it was C1225 (driver front, excessive wheel speed variation). And just as before, if cleared the codes would set again once the car was driven any distance, and there was ABS activity while it determines the fault. Back to the shop where they confirmed that the driver ABS tone ring had similarly disintegrated.
The second attached image is the driver side old hub assy. In this case most of the tone ring is gone, only a small arc remains.
I am perplexed that both tone rings would fail so close in mileage/age. An errant piece of gravel is not to blame here. YonderGod mentions something very similar in https://gm-volt.com/forum/showthread.php?325299-Wheel-Speed-Sensor-DIY-repair
I wonder how many of you have had issues with the ABS/Intellitrak system due to ASB tone rings/hubs?
-russella
A note on the the symptoms and driveability of the car once these faults are detected: ABS is not active, no traction control or stability (of course). After cycling ignition, the Check Engine light will be added to the mix of other lights in the instrument cluster. Hitting the regular service brake won't use any electrical regen...only friction brakes (you do get regen in L though). If you try to use the parking brake to slow the vehicle when moving it will also turn on the the parking brake yellow warning light and set a code (I don't recall which), and parking brake stopping distance is much larger than normal. Finally there is some subtle hunting/surging that occurs at cruising speeds, especially on a slight downhill (no idea why.)
Box for the new pass hub lists GM# 1358-5466, and box for driver side lists 1350-7016.
Another note on the tone ring: My auto-component knowledge is a bit outdated so when looked down into the hole of the sensor, I was surprised not to see a toothed wheel, which I hoped to inspect or clean. The new systems use a thermo-set plastic with magnets or ferro-magnetic buttons embedded inside. https://patents.google.com/patent/US8020676 It's pretty hard to see much down the bore hole for the sensor anyway.
