Generac Power Systems CorePower Repair Manual page 80

Section 4.5
Diagnostic Tests
Procedure
1. Disconnect Wire 18 at the bullet connector. See Figure 61.
2. Connect a jumper wire from the stud to which Wire 56 is
connected on the Starter Contactor (SC) and 12 VDC Wire
15B at TB1 (Customer Connection). The generator will
start cranking. As it is cranking, repeat Test 70.
3. If spark now occurs with Wire 18 removed, check for
a short to ground. Remove the J1 Connector from the
circuit board.
4. Set a VOM to measure resistance. Connect one test lead
to Wire 18 (disconnected in Step 1). Connect the other
test lead to a clean frame ground. INFINITY should be
measured.
5. Reconnect the J1 Connector to the controller.
Results
1. If INFINITY was not measured in Step 4, repair or replace
shorted ground Wire 18 between the J1 Connector from
the controller to the bullet connector.
2. If INFINITY was measured in Step 4, replace the controller
and retest for spark.
3. If ignition spark still has not occurred, proceed to Test 67.
Page 78
PART 4
ENGINE/DC CONTROL