Midtronics Inc. 7000 Monroe Street Willowbrook, IL 60527
www.midtronics.com
19
Chapter 4: Cable Drop Test
EXP-1002
When starting or charging system test results indicate
there may be a problem, a Cable Drop Test can deter-
mine if it is due to worn cables or bad connections
between the battery and the alternator or starter.
Worn cables or bad connections create higher resistance,
which causes a drop across the circuit. The voltage drop
reduces current carrying capability that displays the same
symptoms as a weak alternator or starter and causes
premature battery failure.
There’s no need to run the engine. The Cable Drop Test sends
a signal through the circuit at the component under test. The
tester then simultaneously calculates voltage drop on the
positive (+) and negative (–) sides of any circuit as well as the
total voltage drop. The amperage range for each of the four
tests is 0 to 1000 A. When you change the setting from the
factory defaults, the tester will store your setting in memory
for your next test.
There are three preset tests:
•
BATTERY GROUND
•
STARTER CIRCUIT
•
ALTERNATOR CIRCUIT
A fourth test, OTHER CIRCUIT, tests other grounds and circuits
against your specified amperage capacity.
The test requires two test lead connections, as shown.
R
Battery
Battery Test Lead
DMM Test Lead
Component
Under
Test
1
R
2
+
–
Red
Red
Black
Black
•
Battery test leads at the component’s output lead (the B+
or output screw on the alternator) and the component’s
housing as ground
•
DMM test leads at the battery terminals
NOTE: The test requires a complete circuit. If
you’re testing a system with a remote solenoid,
you can test from the battery to the solenoid, but
not from the battery to the starter.
1. To begin, select the Cable Drop Test icon in the Main Menu
and follow the instructions on the display.
IMPORTANT: For accurate results the battery
should be good and fully charged before you
perform a test.
Performing A Test
The Battery Ground Test measures the voltage drop for the
ground strap.
2. Use
or
to select the circuit type and press NEXT to
continue, or press the corresponding number key.
1
BATTERY GROUND
2
STARTER CIRCUIT
3
ALT CIRCUIT
4
OTHER
3. Use
or
to select the rated amperage or output of
the circuit and press NEXT to continue, or press the cor-
responding number key. The default value will vary de-
pending on the circuit type selected.
80
A
4. Connect the main clamps (battery test leads) to the bat-
tery and ground: positive (+) clamp to the battery’s posi-
tive post; negative (–) clamp to the vehicle chassis.
5. Connect the DMM cable to the battery posts: positive (+)
clamp to the positive post; negative clamp (–) to the nega-
tive post.
For the next few seconds the tester will display the word
TESTING and a stopwatch while it evaluates the battery
ground.
Cable Drop Test Results
Voltage
drop across
negative
side of
circuit
Total
circuit
voltage
drop
Voltage
drop across
positive side
of circuit
If there is a problem, the decision is CLEAN AND RETEST OR
REPLACE. To print the results, align the tester’s IR transmitter
with the printer’s receiver, and select PRINT. To return to the
Main Menu, press END.
Chapter 4: Cable Drop Test
