4. Reconnect first set of batteries and disconnect
second set.
5. Repeat steps 2 and 3 for first set of cables.
6. Replace cables or repair circuits with excessive
voltage drop.
3-12. TEST COMPLETION.
If temporary 12 volt test
connections were made for 24 volt system, reconnect
batteries to vehicle specifications for 24 volt operation
before starting vehicle. However, if the tests following
are to be performed, keep the temporary 12 volt hook-up.
3-13. STARTER SOLENOID CIRCUIT
TEST
The starter shifting in and out, or not pulling in, is
often caused by high resistance in the starter solenoid
circuit. When the solenoid circuit has excessive voltage
loss, the starter pinion may not engage the flywheel. If
it does engage, it may drop out too soon when battery
voltage lowers. The solenoid circuit usually consists of
a magnetic switch with leads to and from the starter
solenoid. Some vehicles use only a pushbutton switch
to control the starter solenoid and this same test applies.
NOTICE
For starters with an integral magnetic
switch, use the test procedures specific to
those starters.
NOTICE
When testing 24 volt systems, use the same
temporary 12 volt connection as for Battery
Cable Test, paragraph 3-7.
3-14. SOLENOID CIRCUIT VOLTAGE LOSS TEST
(See Figure 3-5).
Disconnect
1. Lead to “S” terminal on starter solenoid.
Connect
1. Carbon pile to switch wire lead and to starter
ground terminal (a small clamp or jumper wire may be
helpful).
2. Positive lead of digital voltmeter set on low scale
to solenoid “BAT” terminal.
3. Negative lead of voltmeter to switch wire lead
to which carbon pile is connected. Meter will show
battery voltage.
NOTICE
In the following step, if the magnetic switch
does not close on a 12 volt vehicle, perform
Magnetic Switch Circuit Test, paragraph 3-
18, then return to this point in the Starter
Solenoid Circuit Test.
NOTICE
In the following step, on a 24 volt vehicle, if
the temporary 12 volt system will not close
the magnetic switch, bypass it with a heavy
jumper connected between the two large
studs on the magnetic switch. electrically
this does the same thing as pushing the
button and closing the switch.
With no
button to release,
the jumper must be
disconnected after each voltage reading.
Test
1. Have assistant push starter button with key
on. Listen for sound of magnetic switch closing.
Voltmeter reading should be zero.
2. Turn on and adjust carbon pile to 100 amp load
(60 amp if 24 volt system).
3. Read and record voltage (V6) on voltmeter.
4. Voltage loss shall not exceed:
12 volt system - 1.0 volt
24 volt system - 2.0 volt
5. If circuit voltage loss is less than maximum,
solenoid circuit is OK, Turn off and disconnect carbon
pile and proceed to Magnetic Switch Circuit Test,
paragraph 3-18. If voltage loss exceeds maximum, loss
is excessive. This may be caused by loose terminals,
corrosion, too small wire, switch located too far from
starter, or worn out magnetic switch. Perform Wiring
Test, paragraph 3-15 and Magnetic Switch Contactor
Test, paragraph 3-16 to isolate the problem.
3-4
CARBON PILE
FIRST SET
SECOND SET
NEGATIVE
VOLTAGE
LOSS
Figure 3-4. Battery Cable Test - Typical Dual
Box 12 Volt System
POSITIVE
VOLTAGE
LOSS
DP-1022
new diagnostic manual 4/5/05 9:48 AM Page 3-4
This document, and more, is available for download from Martin's Marine Engineering Page - www.dieselduck.net
