Generac Power Systems 53187 - Manual (Page 139)

PARTS
ENGINE ELECTRICAL SYSTEM
1
Test 20- Test Control Relay CR2 (Contin­
ued)
PROCEDURE (CONT’D);
To test run relay CR2, proceed as follow s:
1. Disconnect all w ires from the relay term inals except
W ire 0 (ground). W ire 0 m ust rem ain connected to relay
term inal A.
2. Set a VOM to its "Rx1“ scale and zero the m eter.
3. Connect one VOM test lead to relay term inal #7, the
other test lead to relay term inal #4. W ith the relay
de-energized, the m eter should read "infinity".
4. W ire 15 w as previously disconnected from relay
term inal #7. This w ire is electrically hot. Connect W ire
15 to relay term inal #B.
a. The relay should energize and its norm ally-open
contacts should close.
b. The VOM connected in Step 3 should read "con­
tinuity".
RESULTS;
1. Replace the run relay if it is defective.
2. If the relay tests good, go to Test 21.
Test 21- Test Engine Control Circuit
Board
DISCUSSION;
The engine control circuit board cannot be repaired
in the field. If the board is defective, it m ust be replaced.
PROCEDURE;
To test the engine control circuit board, proceed as
follow s:
1. Set a VOM to read battery voltage (12 VDC).
2. Type 1 DC Control System ; Check that DC pow er
is available to the circuit board as follow s:
a. Connect the m eter’s positive (+) test lead to Ter­
m inal #1 of the circuit board; the com m on {-) test lead
to Term inal #2 (ground).
b. Hold the start/slop sw itch at "Start". The m eter
should read battery voltage (indicating that crank
relay CR1 has energized).
c. If the engine starts, release the start/stop sw itch.
The VOM should still read battery voltaoe (indicating
that run relay CR2 has energized and Is holding the
pow er supply to the board).
Type 2 & 3 DC Control System : Check that DC pow er
is available to the circuit board as follow s:
a. Connect the m eter’s positive {+) test lead to Ter­
m inal #1 of the circuit board; the com m on (-) test lead
to Term inal #2 (ground).
b. The m eter should read battery voltage, indicating
that fused battery voltage Is available to the circuit
board.
3. Now , connect the VOM positive (+) test lead to circuit
board Term inal #7, to w hich W ire 56 connects; the
com m on (-) test lead to Term inal #2 (ground). Set the
start/stop sw itch to "Start" and the m eter should read
battery voltage.
SECTION 5.9
TROUBLESHOOTING TEST PROCEDURES
4. Connect the positive (•»■ ) VOM test lead to circuit
board Term inal #9; the com m on VOM test lead to
Term inal #2 (ground). Set the start/stop sw itch to
"Start" and battery voltage should be indicated. Re­
lease the start/stop sw itch and battery voltage should
still be indicated.
5. Repeat Step 4 w ith the positive (-t-) VOM test lead
connected to circuit board term inal #10; the com m on
(-) test lead connected to Term inal #2. Expect the sam e
results as in Step 4.
6. Repeat Step 4 w ith the positive (+) VOM test lead
connected to circuit board Term inal #11; the com m on
test lead at Term inal #2. Expect the sam e results.
Figure 7. Engine Control Circuit Board
RESULTS:
1. Replace the engine control circuit board if defective.
2. If the engine cranks, starts and then shuts dow n
w hen the start/stop sw itch is released, but the circuit
board tests good, go to Test 22.
Test 22- Test Low Oil Pressure Switch
DISCUSSION;
If the engine cranks, starts and then shuts dow n
w hen the start/stop sw itch is released, one possible
cause of the problem is a defective low oil pressure
sw itch. The sw itch is norm ally-closed, but is held open
by engine oil pressure during cranking and running.
Closure of the sw itch contacts w ill result in engine
shutdow n.
PROCEDURE;
If the engine w ill not start, unplug the connector
from the low oil pressure sw itch term inal. Then, try a
start. If engine starts w ith w ire disconnected from
sw itch term inal, but w ill not start w hen w ire is con­
nected, the low oil pressure sw itch m ust be defective.
Another w ay to test the pressure sw itch is w ith a
volt-ohm -m illiam m efer (VOM). Test the sw itch w ith a
VOM as follow s:
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