Generac Power Systems GP Series Diagnostic Repair Manual page 43

b. 0.10-0.20 VDC on a ground connection.
c. 0.20-0.30 VDC across a wire or cable (V1, V2).
d. 0.20-0.30 VDC across a switch or starter
contactor (V3).
e. 0.40-0.50 VDC across the entire circuit
B
A. V1
B. V2
C. V3
Figure 5-64. Starter Circuit Voltage Drop Test
Connections
D. V4
Figure 5-65. Starter Circuit Voltage Drop Test
Connections
If voltage drop is greater than the above, based on
7.
the circuit or component, clean or replace the failed
connection or component. If voltage drop test
results are within the above, based on the circuit or
component, refer back to the flowchart.
Test 13 – Testing Key Start Switch
(KSS)
General Theory
The key start switch (KSS) activates the system (ECM,
fuel pump, etc.) when set to the ON position. When
moved to the START position, the starter contactor circuit
is completed to ground. If the KSS is not operating
properly, the system may fail to activate, or the engine
may fail to start.
Procedure
Remove the control panel faceplate screws and
1.
pull the control panel back on the left side to
access the engine switch.
Disconnect the KSS.
2.
Set DMM to measure resistance/continuity.
3.
Set the KSS to the OFF position.
4.
Diagnostic Repair Manual
A
C
D
a. No continuity should be measured between
terminals.
Set the KSS to the ON position.
5.
a. Continuity should be measured between the
brown (BAT) and the white (PS) wires.
Hold the KSS in the START position.
6.
a. Continuity should be measured between the
brown (BAT) and the white (PS) wires and
between the red/brown (ST) and the red (E)
wires.
If continuity is different than what is stated in Steps
7.
5 and 6, replace the KSS.
Wire 14A
Terminal PS
OFF
ON
002399
START
Test 14 – Check Starter Motor (SM)
The following conditions affect starter motor (SM)
performance:
• Binding or seizing in starter motor bearings.
•
A shorted, open, or grounded armature.
– Shorted, armature (wire insulation worn and
004741
wires touching), indicated by low or no RPM.
– Open armature (wire broken), indicated by low
or no RPM and excessive current draw.
–
Grounded armature (wire insulation worn and
wire touching armature lamination or shaft),
indicated by excessive current draw or no
RPM.
• A defective key start switch (KSS).
• Broken, damaged or weak magnets.
• Starter drive dirty or binding.
• Continually blowing 10A fuse (F2) on startup.
Figure 5-66. Starter Motor (SM)
Section 5 Engine Diagnostic Tests
15 183
BAT ST
14B
E
015039
37