Rick's Free Auto Repair Advice

ABS light on, TRAC off, Stabilitrac

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

wheel bearing hub unit showing the magnetized speed sensor ring

Clean the Nitrile rubber ring

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 Muscoplat

Posted on by Rick Muscoplat

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