ABS light on, TRAC off, Stabilitrac off – What does it mean?
If you own one of the GM vehicles listed below and have any of these warnings: ABS light on, TRAC off, Service Traction Control System light on, Service Stabilitrak light and/or have the following trouble codes stored; C0035, C0040, C0045, C0050, on you should read this service bulletin #PIC5248E from GM.
C0035 Left Front Wheel Speed Sensor Circuit
C0040 Right Front Wheel Speed Sensor Circuit
C0045 Left Rear Wheel Speed Sensor Circuit
C0050 Right Rear Wheel Speed Sensor Circuit Plausibility Failure
Other ABS stabilitrac symptoms
In addition to the warning lights, you may also hear a brief and intermittent noise, click, ratchet, grind, or ABS pump motor noises from the inside of the vehicle at parking lot speeds when braking. Or, if your vehicles is equipped with Electric Power Steering you may also notice a Service Steering Message displaying in the Driver Information Center (DIC). You will most likely experience heavier steering feel at low speed or static steering maneuvers when this happens. This condition is normal when the vehicle loses signal from a wheel speed sensor.
Vehicles affected by this service bulletin
2008-2013 Buick Enclave
2010-2013 Buick LaCrosse
2011-2013 Buick Regal
2012-2013 Buick Verano
2008-2013 Cadillac CTS/CTS-V
2010-2013 Cadillac CTS Wagon
2011 2013 Cadillac CTS/CTS-V Coupe
2010-2013 Cadillac SRX
2013 Cadillac XTS – FWD Models (rear non-driven wheel bearings only)
2010-2013 Chevrolet Camaro
2011-2013 Chevrolet Camaro Convertible
2009-2012 Chevrolet Colorado
2011-2013 Chevrolet Cruze, Volt
2010-2013 Chevrolet Equinox
2014 Chevrolet Impala (New Body Style)
2013 Chevrolet Malibu
2009-2013 Chevrolet Traverse
2009-2012 GMC Canyon
2007-2013 GMC Acadia
2010-2013 GMC Terrain
2007-2010 Saturn Outlook
The cause of these trouble codes and braking noise is debris accumulation on the magnetic “tone” wheel built into the wheel bearing. You do NOT have to replace the wheel bearing to correct this problem. Here’s why:
Older ABS braking systems used a steel toothed ring and a magnetized wheel speed sensor. As rust accumulated on the tone ring it would throw debris onto the magnetic sensor and that debris would interfere with the signal, causing the ABS to activate prematurely.
GM changed the wheel speed sensor and tone rings in these vehicles. Now, instead of a steel tone ring, it is a rubberized ring with magnetic North and South poles molded into the nitrile rubber (like a magnetic business card). The wheel speed sensor is inside the wheel bearing and the tone ring is mounted on the outside of the like a seal in a sealed bearing. Great idea but bad execution on GM’s part. GM figured that the elimination of the steel tone ring would stop the accumulation of metallic debris. That’s partially true. But there’s enough metallic debris on the road that any accumulation on the magnetized rubber ring can throw off the wheel speed sensor.
Fix the wheel bearing
Inspect the wheel bearing associated with the trouble code. Look for debris build up on the magnetized ring. Wipe it off with a dry nylon bristle brush. If that doesn’t
remove all the debris, wash the ring with mild soap detergent. Then clear the trouble codes and test drive.
In some severe cases, you may have to remove the wheel bearing to remove all the debris.
If the codes are still present and the ring is clean, proceed with normal diagnostic procedures.
©, 2015 Rick MuscoplatPosted on by Rick Muscoplat