Test 12 - Check Stepper Motor Control - Generac Power Systems 7 kW NG Repair Manual

Section 2.4
Diagnostic Tests
Tools Required
• A meter that is capable of measuring AC frequency
Procedure
1. See Figure 46, connect an accurate AC frequency meter
across the Wires 11 and 44 Terminals of the generator
main line circuit breaker (MLCB)
2. Set the AUTO-OFF-MANUAL to the MANUAL position.
3. Let engine stabilize. Measure and record the frequency.
Results
1. If the meter indicated 59-61 Hertz, refer back to flow
chart
2. If the meter indicated a value outside the accepted range,
refer back to flow chart.
TEST 12 – CHECK STEPPER MOTOR
CONTROL
Procedure: V-Twin
1. Remove air cleaner cover to access Stepper motor.
2. Physically move the throttle and verify the Stepper motor,
linkage and throttle do not bind in any way, if any binding
is felt repair or replace components as needed. The
Stepper motor will have resistance as it moves through its
travel.
3. Physically move the throttle to the closed position by
pulling the Stepper motor arm towards the idle stop. See
Figure 55 for 8kW units, Figure 56 for 10kW units, and
Figure 57 for 12-20kW units.
4. Set the AUTO-OFF-MANUAL switch to the MANUAL
position.
5. Observe record the Stepper motors movement.
6. Set the AUTO-OFF-MANUAL switch to the OFF position.
STEPPER MOTOR
PULL ARM THIS
DIRECTION TO
CLOSE THROTTLE
Figure 55. Throttle Positions 8kW Units
Page 56
PART 2
PULL ARM THIS
DIRECTION TO
CLOSE THROTTLE
Figure 56. Throttle Positions 9/10kW Units
PULL ARM THIS
DIRECTION TO
CLOSE THROTTLE
STEPPER MOTOR
STEPPER MOTOR ARM
Figure 57. Throttle Positions 12-20kW Units
7. Physically move the throttle to the open position by pulling
the Stepper motor arm away from the idle stop.
8. Set the AUTO-OFF-MANUAL switch to the MANUAL
position.
9. Observe and record the Stepper motors movement.
10. Set the AUTO-OFF-MANUAL switch to the OFF position.
11. If no movement was seen in Step 5 or 6 remove the
controller and verify the six pin connector on the controller
is seated properly, remove the connector and then replace
it and test again. If problems persist, proceed to Step 12.
12. Set Volt-Ohm-Milliammeter (VOM) to measure resistance.
Note: Press down with the meter leads on the connectors
exposed terminals, do not probe into the connector.
13. Connect the meter test leads across points A and B as
shown in Table 15 and compare to the specified value.
See Figure 58 for pin locations.
AC GENERATORS
STEPPER MOTOR
STEPPER MOTOR ARM