Cadillac Wheel Speed Sensors
This bulletin applies to 2013-2014 Cadillac ATS, 2008-2014 CTS, 2010-2016 SRX and 2013-2017 XTS vehicles. Customers may comment on any of the following:
The ABS. Service Traction Control System and/or Service Stabilitrak telltale lights are on. During an initial scan for EBCM module diagnostic codes, the technician may find one or more DTCs (C0035-C0050) with specific symptom bytes 18, 5A, DF.
A brief and intermittent noise, click, ratchet, grind or ABS pump motor noises typically heard from inside the vehicle at parking lot speeds.
A flashing Traction Control or Stabilitrak warning at low speeds.
For vehicle equipped with electric power steering, the operator may also notice a Service Steering message displayed and will experience heavier steering feel at low speed. This will be accompanied by the power steering control module setting DTC U0415. This is a normal default action with the loss of a wheel speed sensor signal. If DTC U0416 remains after removal of the wheel speed sensor debris, refer to published diagnostics.
These conditions may be caused by single or multiple pieces of ferrous metal debris stuck to the wheel speed sensor magnetic encoder ring. Inspect and clean as necessary. Note that this does not apply to capped wheel bearings.
This is a magnetic encode ring.
Some new models have begun to use a different type of wheel speed sensor encode ring (tone wheel). Instead of a traditional mechanical type tooth tone wheel, the wheel speed sensor tone wheel is now made of a magnetized nitrile rubber ring, typically brown in color. This magnetic encoder consists of multiple North and South pole pairs surrounding the outer circumference. When this magnetic encoder ring rotates and passes by the wheel speed sensor head, it generates a sign wave in the wheel speed sensor. The wheel speed sensor converts an analog signal to a digital square wave and typical digital signal values switch between 7mA (low) and 14mA (high) DC current.
This is a newer magnetic encoder ring used in newer bearing designs feature North/South poles.