Mastering Diagnostics No. 32: Capturing Intermittent Parasitic Drains with a Lab Scope
In this episode of Mastering Diagnostics, Motor Age’s Brandon Steckler takes on one of the most frustrating challenges in modern automotive diagnostics: intermittent parasitic battery drains. When a vehicle arrives with a dead battery but shows no measurable drain during testing, traditional diagnostic methods can leave even seasoned technicians at a loss.
Steckler explains how today’s layered vehicle networks play a major role in these elusive failures. Modern CAN systems operate at varying speeds depending on their function. While high-speed networks support mission-critical systems like airbags and ADAS, medium-speed networks often manage comfort and security features. Many of these systems “sleep with one eye open,” remaining partially active to monitor for disturbances while conserving battery power.
Rather than relying solely on static current measurements, Steckler demonstrates a strategic approach: leveraging the PicoScope 4425A to capture network activity over time. By recording and analyzing these intermittent wake-up events, technicians can correlate network disturbances to battery drain and pinpoint the root cause with confidence.
If you’ve ever faced a “no problem found” parasitic drain only to see the vehicle return weeks later, this episode of Mastering Diagnostics will help you rethink your strategy and eliminate the guesswork. Click here to learn more about the PicoScope 4425A.
About the Author
Brandon Steckler
Technical Editor | Motor Age
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.