Test 57 - Check Wire 56 Voltage; Test 58 - Test Starter Contactor - Generac Power Systems CorePower Repair Manual

ENGINE/DC CONTROL
5. Test Battery Condition:
a. 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.
b. 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, and 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 with a new battery.
TEST 57 – CHECK WIRE 56 VOLTAGE
Discussion
During an automatic start or when starting manually, a crank
relay on the controller should energize. Each time the crank
relay energizes, the controller should deliver 12 VDC to the
starter contactor (SC), and the engine should crank. This test
will verify (a) that the crank relay on the controller is energizing,
and (b) that controller action is delivering 12 VDC to the starter
contactor.
Procedure
1. Set a VOM to measure DC voltage.
2. Connect the positive (+) test probe of a DC voltmeter
(or VOM) to the Wire 56 connector of the star ter
contactor the star ter contactor (SC). Connect the
common (-) test probe to frame ground.
3. Observe the meter. Then, set the AUTO-OFF-MANUAL
switch to the MANUAL position. The meter should
indicate battery voltage. If battery voltage is measured,
stop testing and refer back to flow chart.
4. Set a VOM to measure resistance.
Note: Remove 7.5 amp fuse before disconnecting J1 con-
nector.
5. Remove Wire 56 from the starter contactor. Connect one
meter test lead to disconnected Wire 56. Remove the J2
Connector from the controller. Connect the other test lead
to J2-11 (Wire 56). CONTINUITY should be measured. If
CONTINUITY is not measured, repair or replace Wire 56.
Results
1. If battery voltage is indicated in Step 3 refer back to flow
chart.
PART 4
TEST 58 – TEST STARTER CONTACTOR
Discussion
The starter contactor (SC) must energize and its heavy duty
contacts must close or the engine will not crank. This test will
determine if the starter contactor is in working order.
Procedure
Carefully inspect the starter motor cable that runs from the
battery to the starter motor. Cable connections must be clean
and tight. If connections are dirty or corroded, remove the cable
and clean cable terminals and terminal studs. Replace any
cable that is defective or badly corroded.
Use a DC voltmeter (or a VOM) to perform this test. Test the
starter contactor as follows:
1. Connect the positive (+) meter test lead to the starter
contactor stud (Test Point 1). Connect the common (-)
meter test lead to a clean frame ground. Battery voltage
(12 VDC) should be indicated.
2. Connect the positive (+) meter test lead to the starter
contactor stud to which the starter motor cable attaches
(Test Point 2). Connect the common (-) test lead to frame
ground.
a. No voltage should be indicated initially.
b. Set the AUTO-OFF-MANUAL switch to MANUAL. The
meter should now indicate battery voltage as the starter
contactor energizes.
56
TO CONTROLLER
0
TO GROUND
TO BATTERY
Figure 40. The Starter Contactor
Results
1. If battery voltage was indicated in Step 1, but NOT in Step
2b, replace the starter contactor.
2. If battery voltage was indicated in Step 2b, but the engine
did NOT crank, refer back to flow chart.
Section 4.5
Diagnostic Tests
16
TO STARTER
TEST POINT 2
TEST POINT 1
13
TO FUSE (F1)
13
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