ACtion Magazine - April 2016 - (Page 14)
For diagnostics, being well grounded in the fundamentals is the key to success.
Contributed in part by Bob Chabot, ManicMedia LLC
Pete Meier / Motor Age Magazine
In addition, he provided a number of A/C and cooling system
case studies to demonstrate real world problem solving. Here are
some of the key insights he shared.
Current has to be in spec for an electrical circuit to operate
"In the real world, it is unwanted resistance, not
changes in voltage, that causes most electrical problems," Pete Meier shared.
Every day electrical troubleshooting
"Expert mobile diagnosticians tell me that more than 80 percent of what they do everyday ought to be able to be done by
any shop technician with good fundamentals," noted Pete Meier,
whose Mastering Electrical Troubleshooting seminar at the
Mobile Air Conditioning Society's 2016 annual trade show and
training event helped shop owners, technicians and educators
get a grip on the know-how required to troubleshoot A/C and
other issues effectively and efficiently.
"That's the good news. It's also the bad news. Getting and
keeping a sound understanding of those fundamentals is an increasing problem in modern shops, as vehicles continue to become more electrical in nature and driven by software." Meier's
lengthy presentation (now available on the MACS website) covered the resources required to be competent and remain current.
ACTION * April 2016
"Anything that alters the ability of current to flow as designed can be
considered an 'unwanted' source of resistance," Meier explained. "Examples include an open circuit, shorts to ground, electronic control module parasitic drains and others. Remember that there are also switches
and connectors between the two and they have some, but not a great deal
of resistance, compared to loads such as motors.
"But checking power and grounds on a problematic circuit statically
can be a waste of time that will lead you down the rabbit hole," Meier
added. "If you cannot perform dynamic voltage drop tests in today's
shop, you aren't going to be able to solve an increasing amount of vehicle
problems. For example, some automakers are designing-in voltage drops
to control operation." To help attendees assimilate the knowledge, Meier
described two different ways to perform voltage drop troubleshooting
tests, along with a number of case studies with walk-through discussion
Diagnosing electrical concerns goes beyond current testing
"A complete diagnosis is not limited to just current testing," Meier
continued. "Understanding the factors that influence current demand can
help you identify and locate a variety of problems, especially in circuits
utilizing electric motors or dependent on the strength of a magnetic field
- typical in many air conditioning applications."
"Many technicians I talk to say parasitic battery drains are more
common than they used to be; in particular, drains in circuits controlled
by a relay in an Electronic Control Unit (ECU). These components can
be difficult to test directly. Examples include A/C compressors mounted
in hard to reach areas or fuel pumps immersed inside fuel tanks." Meier
showed attendees a test procedure to quickly isolate where the problem
Table of Contents for the Digital Edition of ACtion Magazine - April 2016
ACtion Magazine - April 2016
Training is key offering at 2016 MACS
Networking at MACS
By the Numbers
New Products and Services
ACtion Magazine - April 2016