Engine Cranking - Guardian 5240 Diagnostic Repair Manual

SECTION 4.2
OPERATIONAL ANALYSIS
• After ten (10) seconds and when the circuit board's 10-second timer has timed out, if utility voltage is still below
65 percent of nominal, circuit board action will energize the circuit board's crank and run relays simultaneously.
• Printed circuit board action delivers 12 volts DC to a starter contactor relay (SCR), via Wire 56. When the SCR
energizes, its contacts close and battery power is delivered to a starter contactor (SC). When the SC energizes,
its contacts close and battery power is delivered to the starter motor (SM).The engine cranks.
0 3
2
1
BATTERY
CHARGER
13
0
0
SCR
56
ELECTRONIC
VOLTAGE
REGULATOR
MANUAL
194
194
15
15
J2
CONTROL
PRINTED CIRCUIT
BOARD
Page 86
UTILITY VOLTAGE DROPOUT AND ENGINE CRANKING
= 12 VDC ALWAYS PRESENT
= AC VOLTAGE
= GROUND FOR CONTROL PURPOSES
224B
1
225B
2
13
0
15
16
56
11
22
4
4
0
6
2
GOVERNOR
ACTUATOR
AUTO
194
15A
15A
15A
SW1
239
239
15
SW2
15B
1 15A
J1
2 4
3 23
4 86
5 18
6
7
8 LC1
9 56
10 224
11 239
12 85
13
14
15 LC2
16 14
17 225
18
19 15B
20 0
21
22
23 90
0
0
16 0
22 11
4 56 15
194
0
F1
15
14
14
CS 14
PART 4
DC CONTROL
= 12 VDC DURING CRANKING ONLY
= 12 VDC DURING ENGINE RUN CONDITION
224B
13 225B 18 86
13
23 18 86 LC1
14
18
86
85
85
4
13
6
2
16
14
0
0
11
22
LC1
LC2
0
23
194
225B
224B
85 LC2 0
224
14
225