C.E. Niehoff & Co. C130/C131/C132 Inst/Parts Rep/TG Combo Guide - Manual (Page 12)

Page 12 SM40A
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Dealer, please contact us at:
C.E. Niehoff & Co.
2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada •
TEL: 847.866.6030 outside USA and Canada •
FAX: 847.492.1242 •
E-mail us: [email protected]
Visit our Web site: www.CENiehoff.com
Testing Electrical Components
Testing Guidelines
Professional service technicians rely on these
guidelines when testing electrical components.
Voltage testing:
• Set meter to proper scale and type (AC or DC).
• Be sure to zero the meter scale or identify the
meter burden by touching meter leads together.
Meter burden must be subtracted from final
reading
obtained.
• Be sure the meter leads touch source area only.
Prevent short circuit damage to test leads or
source by not allowing meter leads to touch other
pins or exposed wires in test area.
Resistance (ohm) testing:
• Set meter to proper scale.
• Be sure to zero the meter scale or identify the
meter burden by touching meter leads together.
Meter burden must be subtracted from final
reading
obtained.
• Be sure the meter leads touch source area only.
Prevent altering the reading by not allowing fingers
or body parts to touch meter leads or source
during
reading.
• Be sure reading is taken when source is at 70ºF.
Readings taken at higher temperatures will
increase the reading. Conversely, readings taken at
lower temperatures will decrease the reading.
• Be sure to test directly at the source, testing
through extended harnesses or cable extensions
may increase the reading.
Voltage drop testing:
• Measure voltage between B+ on alternator or
source and B- (ground) on alternator or source.
Record obtained reading. Move to batteries or
other source and measure again between B+ and
B- terminals on battery or other source. Difference
between the two readings represents voltage lost
within the circuit due to but not limited to inade-
quate cable gage or faulty connections.
• Voltage drop measurements must be taken with
all electrical loads or source operating.
Dynamic/Live testing:
• Definition: Connecting power and ground to a
component to test operation/function out of circuit.
• Be sure to directly and securely jumper leads to
source terminals of the component being tested.
• Be sure to touch the contact end of jumper leads
only to the power supply or battery terminals.
Touching a contact end to component terminals
may create an arc and damage component terminals.