Guardian 4389 Repair Manual page 118

SECTION 4.4
DIAGNOSTIC TESTS
3. Connect one test lead to Wire N1 at the terminal strip in
the generator control panel. Connect the other test lead to
Wire N2. Utility line-to-line voltage should be measured.
RESULTS:
1. If voltage was measured in Step 3, go to Test 65.
2. If voltage was not measured in Step 3, go to Test 28.
TEST 72 - CHECK UTILITY SENSING VOLTAGE
AT THE CIRCUIT BOARD
DISCUSSION:
If the generator starts and transfer to STANDBY
occurs in the automatic mode, even though an
acceptable UTILITY source voltage is available from
the Transformer (TX), the next step is to determine if
that sensing voltage is reaching the circuit board.
PROCEDURE:
1. Set the AUTO-OFF-MANUAL switch to OFF.
2. Disconnect Connector J1 from the circuit board.
3. Set a VOM to measure AC voltage.
4. Connect one meter test lead to Pin Location J1-14
(Wire 225). Connect the other test lead to Pin Location
J1-15 (Wire 224). Approximately 14-16 VAC should be
measured.
RESULTS:
1. If voltage was measured in Step 4, replace the circuit
board.
2. If voltage was NOT measured in Step 4, repair or
replace Wire 224 and/or No. Wire 225 between
Transformer (TX) and Circuit Board Connector J1.
TEST 73 - TEST SET EXERCISE SWITCH
DISCUSSION:
If the Set Exercise Switch (SW2) fails closed, the unit
will start when in AUTO. In normal operation the
Normally Open contacts close when the switch is
depressed. This will ground Wire 351 and reset the
exercise time.
PROCEDURE:
1. Set a VOM to measure resistance.
2. Disconnect Wire 351 and Wire 0 from the Set Exercise
Switch (SW2).
3. Connect one meter test lead to one terminal of SW2.
Connect the other test lead to the remaining terminal of
SW2. The meter should read INFINITY.
Page 116
PART 4
4. With the meter test leads connected to SW2, depress
and hold the switch activated. The meter should read
CONTINUITY.
Figure 35. The Set Exercise Switch
5. Disconnect the five pin connector (J2) from the circuit
board.
6. Connect one meter test lead to Wire 351 (previously
removed from SW2). Connect the other meter test lead
to Pin Location J3 (Wire 351). CONTINUITY should be
measured.
7. Connect one meter test lead to Wire 351 (previously
removed from SW2). Connect the other meter test lead
to the ground terminal. INFINITY should be measured.
8. Connect one meter test lead to Wire 0 (previously
removed from SW2). Connect the other meter test lead to
the ground terminal. CONTINUITY should be measured.
RESULTS:
1. If the Set Exercise Switch (SW2) fails Step 3 or Step 4,
replace the switch.
2. If CONTINUITY was NOT measured in Step 6, OR if it
WAS measured in Step 7, repair or replace Wire 351
between SW2 and Connector J2.
3. If CONTINUITY was NOT measured in Step 8, repair or
replace Wire 0 between SW2 and the ground terminal.
TEST 74 - CHECK REMOTE START WIRING
(IF EQUIPPED)
DISCUSSION:
On some earlier models a remote start connection
was available. If these two wires are connected
together while the generator is in AUTO, the genera-
tor will start.
PROCEDURE:
1. Set the AUTO-OFF-MANUAL switch to OFF.
2. Set a VOM to measure resistance.
3. Disconnect the 17-pin connector (J1) from the circuit
board.
DC CONTROL
351
0