Guardian 4389 Diagnostic Repair Manual page 101

SECTION 4.4
DIAGNOSTIC TESTS
a. An average reading of 1.260 indicates the
battery is 100% charged.
b. An average reading of 1.230 means the
battery is 75% charged.
c. An average reading of 1.200 means the
battery is 50% charged.
d. An average reading of 1.170 indicates the
battery is 25% charged.
C. Test Battery Condition:
1. If the difference between the highest and lowest
reading cells is greater than 0.050 (50 points),
battery condition has deteriorated and the
battery should be replaced.
2. However, if the highest reading cell has a
specific gravity of less than 1.230, the test for
condition is questionable. Recharge the battery
to a 100 percent state of charge, then repeat the
test for condition.
RESULTS:
1. Remove the battery and recharge with an automotive
battery charger, if necessary.
2. If battery condition is bad, replace the battery with a
new one.
TEST 47 - CHECK WIRE 56 VOLTAGE
DISCUSSION:
During an automatic start or when starting manually, a
crank relay (K1) on the circuit board should energize.
Each time the crank relay energizes, the circuit board
should deliver 12 volts DC to a starter contactor
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
delivering 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-
MANUAL 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
Page 4.4-4
PART 4
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.
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
contactor 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.
TEST 48- TEST STARTER CONTACTOR
RELAY (V-T T WIN ONLY)
DISCUSSION:
The starter contactor relay (SCR) located in the
control panel must be energized for cranking to occur.
Once the SCR is energized, it s normally open
contacts will close and battery voltage will be
available to Wire 16 and to the starter contactor (SC).
DC CONTROL