Guardian 4389 Repair Manual page 102

SECTION 4.4
DIAGNOSTIC TESTS
TEST 47 - CHECK WIRE 56 VOLTAGE
DISCUSSION:
During an automatic start or when starting manually,
a crank relay (K1) on the circuit board should ener-
gize. Each time the crank relay energizes, the circuit
board should deliver 12 volts DC to a starter contac-
tor relay (SCR) and the engine should crank. This test
will verify (a) that the crank relay on the circuit board
is energizing, and (b) that circuit board action is deliv-
ering 12 volts DC to the starter contactor relay.
PROCEDURE:
1. Connect the positive (+) test probe of a DC voltmeter (or
VOM) to the Wire 56 connector of the starter contactor
relay (SCR, on models with v-twin engines) or the starter
contactor (SC, on models with single cylinder engines).
Connect the common (-) test probe to frame ground.
2. Observe the meter. Then, actuate the AUTO-OFF-MAN-
UAL switch to MANUAL position.
a. The circuit board crank and run relays should
energize.
b. The meter should indicate battery voltage.
3. Insert the positive (+) meter test lead into Pin 5 of the
circuit board connector J1. Connect the common (-) test
lead to a clean frame ground. Then, repeat Step 2.
a. The circuit board's crank and run relays should
energize.
b. The meter should read battery voltage.
+12 VDC
FIELD
BOOST
RESISTOR
DIODE
CRANK
FIELD
RELAY K1
BOOST
BASE
DIODE
TRANSISTOR
CIRCUIT BOARD
Figure 4. The Wire 56 Circuit
RESULTS:
1. If battery voltage is indicated in Step 3, but NOT in Step
2, Wire 56 (between the circuit board and starter con-
tactor relay or starter contactor) is open. Repair or
replace this wire as required.
2. If battery voltage is NOT indicated in Step 3, go to Test 43.
3. If battery voltage is indicated in both Steps 2 and 3, but
engine does NOT crank, go on to Test 49.
Page 100
13
PIN 5
TO
56
STARTER
PIN 1
STARTER
4
CONTACTOR
FIELD
BOOST
TO
ROTOR
PART 4
TEST 48- TEST STARTER CONTACTOR RELAY
(V-TWIN ONLY)
DISCUSSION:
The starter contactor relay (SCR) located in the con-
trol panel must be energized for cranking to occur.
Once the SCR is energized, it's normally open con-
tacts will close and battery voltage will be available to
Wire 16 and to the starter contactor (SC).
16
13*
56
0
(*OR 15 IF EQUIPPED)
Figure 5. The Starter Contactor Relay
PROCEDURE:
1. Set a VOM to measure DC voltage.
2. Remove Wire 13 from the Starter Contactor Relay (or
Wire 15 if so equipped).
3. Connect the positive (+) meter test lead to the Wire 13
connector. Connect the negative (-) meter test lead to a
clean frame ground. Battery voltage should be measured.
4. Reconnect Wire 13 (or 15) to the SCR.
5. Remove Wire 16 from the SCR. Connect the positive (+)
meter test lead to the SCR terminal from which Wire 16
was removed. Connect the negative(-) meter test lead to
a clean frame ground.
6. Set the AUTO-OFF-MANUAL switch to MANUAL.
Observe the meter reading. Battery voltage should
measured. If battery voltage is NOT measured, proceed
to Step 5.
7. Set the VOM to it's "R x 1" scale to measure ohms.
8. Connect one test lead to the Wire 0 connector. Connect
the other test lead to a clean frame ground. CONTINU-
ITY should be measured.
RESULTS:
1. If battery voltage is NOT measured in Step 3, repair or
replace wiring between starter contactor relay and fuse
(F2).
2. If battery voltage is NOT measured in Step 6 and CON-
DC CONTROL
13/15
16
COM NO
56 0