Mastering Diagnostics #14-The Bypass Test

June 19, 2024
Technical Editor Brandon Steckler demonstrates how the bypass test can prove a diagnosis before committing to a repair or component replacement.

Welcome back to another episode of Mastering Diagnostics with Motor Age Magazine’s Technical Editor, Brandon Steckler. He’s back with another golden nugget to help you along on your path to diagnostic efficiency.

In this episode, Brandon troubleshoots a transmission concern on his 2006 Chevrolet Silverado. The vehicle’s “tow/haul” mode will not function. Brandon takes the time to reference service repair information for a system wiring diagram to first, gain an understanding of how the multiple components work together on a data bus to accomplish the goal of “tow/haul mode.”

He then uses the wiring diagram to identify the types of circuits he will be facing and where the components are located on the vehicle. Collectively, with this information in hand, Brandon sits comfortably at his kitchen table to come up with a diagnostic game plan.

As always, Brandon strives to be as efficient as possible. With that, work as little as possible. More time is spent at the computer than is actually spent disassembling the vehicle. It’s this mindset that prevents time from being wasted during the diagnostic process.

Using his DVOM and a few pierce probes, Brandon quickly determines what is functional in the system. He then employs a bypass test to prove the system will function when the prescribed repair is completed. All of this is determined with very little disassembly and only a small amount of time invested.

Stick with Brandon on this episode of Mastering Diagnostics and learn how the bypass test will take your diagnostic efficiency to the next level!

Due to factors beyond the control of Endeavor Business Media, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage, or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not Endeavor Business Media. The tool and/or equipment featured in this video was supplied by the manufacturer and may or may not be retained by the reviewer at no cost.

About the Author

Brandon Steckler | Motor Age Technical Editor

Brandon began his career in Northampton County Community College in Bethlehem, Pennsylvania, where he was a student of GM’s Automotive Service Educational program. In 2001, he graduated top of his class and earned the GM Leadership award for his efforts. He later began working as a technician at a Saturn dealership in Reading, Pennsylvania, where he quickly attained Master Technician status. He later transitioned to working with Hondas, where he aggressively worked to attain another Master Technician status.

Always having a passion for a full understanding of system/component functionality, he rapidly earned a reputation for deciphering strange failures at an efficient pace and became known as an information specialist among the staff and peers at the dealership. In search of new challenges, he transitioned away from the dealership and to the independent world, where he specialized in diagnostics and driveability. 

Today, he is an instructor with both Carquest Technical Institute and Worldpac Training Institute. Along with beta testing for Automotive Test Solutions, he develops curriculum/submits case studies for educational purposes. Through Steckler Automotive Technical Services, LLC., Brandon also provides telephone and live technical support, as well as private training, for technicians all across the world.

Brandon holds ASE certifications A1-A9 as well as C1 (Service Consultant). He is certified as an Advanced Level Specialist in L1 (Advanced Engine Performance), L2 (Advanced Diesel Engine Performance), L3 (Hybrid/EV Specialist), L4 (ADAS) and xEV-Level 2 (Technician electrical safety).

He contributes weekly to Facebook automotive chat groups, has authored several books and classes, and truly enjoys traveling across the globe to help other technicians attain a level of understanding that will serve them well throughout their careers.