When evaluating intermittent ABS activation without DTCs, which of the following should be checked first?

• A. Brake fluid levels
• B. Tone wheel teeth condition
• C. Wheel speed sensor alignment
• D. Brake line integrity

Answer: (B)

In the context of diagnosing intermittent ABS (Anti-lock Braking System) activation issues, examining the condition of the tone wheel teeth should be the first step. The tone wheel, often referred to as a reluctor ring, plays a critical role in the operation of the ABS by providing the wheel speed sensors with the necessary information to determine if the wheels are locking up during braking. Any damage, misalignment, or foreign material affecting the tone wheel teeth can lead to inaccurate readings from the wheel speed sensors. This can result in false ABS activation or intermittent issues because the ABS module relies on this data to function properly.

Getting a clear and accurate signal from the tone wheel is essential for the uninterrupted performance of the ABS system; variability due to wear or damage could easily result in malfunction. Addressing this first offers a direct path to identifying potential causes of the ABS activation anomalies without delving into other potential issues that might not be the root of the problem.