Auto Service Professional

OCT 2017

Magazine for the auto service professional

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Page 33 of 77

32 | ASP October 2017 Technical command some steering input from the electric power steering (EPS) if equipped even before the driver has a change to recognize the need to do so. Repairing and replacing parts on an ESC-equipped vehicle An up-to-date information system is a must in diagnosing the ESC system and naturally a good scanner. Most ESC systems will provide trouble codes that will lead a tech into the area of concern, commonly involving ABS sensors, yaw or SAS issues. But even a misfire may turn on an ESC light due to the fact the ESC needs the engine to be running properly for it to function as designed. ABS sensor diagnostics and their replace- ment is going to be vehicle dependent. Many WSS are now incorporated in the wheel hub design and are not available separately. Understanding the type of WSS is critical for proper diagnostics. e use of a scan tool is going to be typical and most good generic scanners provide the ABS information needed for diagnosis. Most SAS require some sort of resetting or calibration after replacement, an alignment, steering wheel removal or service or whenever an ESC component is replaced, but don't be surprised if you must perform this even after a battery replacement. Many new alignment racks will now properly recalibrate the SAS after an alignment using proprietary software and the OBD-ll plug. Many newer SASs self-calibrate by requir- ing you to turn the steering wheel slowly lock to lock, and driving the vehicle over a certain mph and distance and will turn off the service light after an appropriate drive cycle. But frequently a scanner is going to be required. Again, I have found a good generic scanner will guide you through the various vehicle- specific SAS calibration procedures. Almost all G sensors (yaw, lateral, or roll rate) will need to be zeroed or initialized after replacement, to allow the ESC to recognize their neutral position. is usually requires the vehicle to be on a flat, level surface and generally in an unloaded state, with the wheels pointed forward. Yet again, a scanner will be required and the proper information on the procedure. Attention to fastener torque, proper sensor orientation and location mounting is impera- tive for proper operation of these sensors. If the ESC unit is going to be replaced, a factory scan tool may be required to install the flash or programming, but some are Even my generic scanner provided the information to help me diagnose this Subaru that needed a steering wheel angle sensor (it turned out it had broken wires).

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