Introduction; Test 13 - Check Fuse; Test 14 - Check Battery And Cables - Generac Power Systems GP Series Diagnostic Repair Manual

Introduction

Perform the Diagnostic Tests in this section in
conjunction with the
Diagnostic Flow
numbers in this chapter correspond to numbered tests in
the flow charts.
NOTE:
Test procedures in this manual are not
necessarily the only methods for diagnosing the condition
of components and circuits. All possible methods that
might be used for system diagnosis have not been
evaluated. If any diagnostic method is used other than
the method presented in this manual, the technician must
be sure that neither personal safety nor product safety,
will be endangered by the procedure or method selected.
Test 13 – Check Fuse
General Theory
See Figure 4-1. The fuse protects the wiring and battery
charger from a short circuit.
Figure 4-1. Typical Fuse
Procedure
Push in fuse holder cap and turn counterclockwise.
Remove cap with fuse. Inspect fuse.
Results
If fuse element melted open, replace fuse with an
identical size fuse. If fuse is good, refer to flow chart.
NOTE: Fuse may be an in-line wire style.
Test 14 – Check Battery and Cables
General Theory
Battery power is used to (a) crank the engine and (b) to
power the circuit board. Low or no battery voltage can
result in failure of the engine to crank and the controller to
blank out and restart in either MANUAL or AUTO modes
of operation. As well, if there is a loose connection or
corrosion associated with a wire (positive or negative),
battery voltage may be present, but because of the high
resistance, will not allow current to flow.
Electrical voltage drop varies according to current flow.
Unless the circuit is operated so current flows through it,
voltage drop cannot be measured. To properly measure
voltage drop, a crank attempt will need to be performed.
This test will determine whether the battery, battery
cables, or both are at fault.
Diagnostic Repair Manual
Procedure A. Inspect Battery Cables, Terminals,
and Connections
Inspect battery cables and battery posts.
1.
Charts. Test
If cable clamps or terminals are corroded, clean
2.
away all corrosion.
NOTE: If corrosion cannot be cleaned or eliminated,
replace the component in question.
Verify all cable clamps are tight. The red battery
3.
cable from the starter contactor (SC) must be
securely attached to the positive (+) battery post.
The black cable from the frame ground stud must
be tightly attached to the negative (-) battery post.
If the above inspection points have been verified
4.
satisfactory, proceed to Procedure B.
Procedure B. Perform a Battery Open Circuit
Voltage Test
Set a DMM to measure DC voltage.
1.
Connect the red meter test lead to the positive
2.
battery post and connect the black meter test lead
to the negative battery post.
Measure and record the open circuit voltage
3.
(OCV).
a. If battery voltage is between 12.1 VDC and 9.0
003971
b. If battery voltage is 12.2 VDC or above and the
Procedure C. Perform a Conductance Test with
a Conductance Type Battery Tester
IMPORTANT NOTE: To properly load test a battery
when using a resistance type load tester, the battery
must be completely full of electrolyte, fully charged and
the load applied must be 1/2 of the battery's CCA Rating.
(e.g. 540/2=270A) For this reason, a resistance type load
tester is not recommended.
Figure 1-2. Conductance Type Battery Tester
Verify the generator is OFF and battery is not being
1.
charged from any source.
Section 4 Engine Diagnostic Tests
VDC, or if engine does not crank (turn over),
proceed to Procedure C.
engine does or does not crank, proceed to
Procedure D.
013030
25