Generac Power Systems Quietpact 75 - Manual (Page 62)

S Se ec cttiio on n 7 7
D DIIA AG GN NO OS ST TIIC C T TE ES ST TS S
Page 60
3. If Step 1 produced spark and Step 2 tested good, set the VOM
to measure DC voltage. Connect one test lead to Wire 15 (J3
Terminal) on ECB. Connect the other test lead to frame
ground. Battery voltage should be measured. Verify that Wire
15 is connected to J3 and that Wire 14 is connected to J2; if
reversed the unit will produce no spark.
4. Rotate the flywheel until the magnet is under the module
(armature) laminations (see Figure 7-37).
5. Place a 0.012-0.015 inch thickness gauge between the fly-
wheel magnet and the module laminations.
6. Loosen the mounting screws and let the magnet pull the mag-
neto down against the thickness gauge.
7. Tighten both mounting screws.
8. To remove the thickness gauge, rotate the flywheel.
9. Repeat the above procedure for the second magneto.
Figure 7-37. – Setting Ignition Magneto
(Armature) Air Gap
10. Repeat Test 55 and check for spark across the spark tester
gap.
11. If air gap was not out of adjustment, test ground wires.
12. Set the VOM to the diode test position. The meter will display
forward voltage drop across the diode. If the voltage drop is
less than 0.7 volts, the meter will “Beep” once as well as dis-
play the voltage drop. A continuous tone indicates “Continuity”
(shorted diode). An incomplete circuit (open diode) will be dis-
played as “OL.”
13. Disconnect the engine ground harness from the ignition mag-
netos and stud connector (see Figure 7-38).
Figure 7-38. – Engine Ground Harness
Figure 7-39. – Diode Failure Diagnosis
14. Connect the positive (+) test lead to Connector ”A” (as shown in
Figure 7-40). Connect the negative (-) test lead to Connector “B.”
a. If meter “Beeps” once and displays voltage
drop, then the diode is good.
b. If the meter makes a continuous tone, the diode
is bad (shorted) and the harness must be
replaced.
c. If the meter displays “OL,” the diode is defective
(open) and the harness must be replaced.
d. Now repeat Steps 14a through 14c with the
negative meter test lead connected to
Connector “C” (Figure 7-40).
15. If the ground harness tested good, check Wire 18A between
the insulated terminal stud and the J1 Connector for a short to
ground. Set a VOM to measure resistance The ground harness
should still be disconnected from the ignition magnetos.
Connect one meter test lead to Wire 18A which is still removed
from the J1 Connector. Connect the other meter test lead to
frame ground. “Infinity” should be measured.
RESULTS:
1. If “Infinity” was not measured in Step 2b, replace the Engine
Control Board.
Note: If VOM was set to Diode test, a reading of
0.5 volts would be observed when the Start-Stop
Switch is set to STOP. If the VOM was set to resis-
tance, a reading of 0.5 to 1.5M ohms would be