Generac Power Systems GP Series Diagnostic Repair Manual page 11

Electronic Engine Control
Section 2
Engine Control Components
Engine Control Module
See Figure 2-9. The Generac 816cc engine is a 2-
cylinder, internal combustion, spark-ignited engine. The
engine is controlled by an engine control module (ECM).
The ECM controls the combustion process to maintain
optimal engine performance. It does this by reading
values from multiple sensors located on various engine
components, interpreting the data, and adjusting engine
fuel flow, timing and intake air flow to maintain proper
speed, performance and emissions characteristics.
Figure 2-9. Engine Control Module
The ECM sends control signals to:
• Main Power Relay
•
Field Boost Relay
•
Fuel pump
• Starter relay
• Throttle body with electronic throttle controller
•
Fuel injectors
• Ignition coils
The ECM receives and monitors signals from:
• Throttle position, intake air temperature, and
manifold air pressure integrated into one sensor
• Crankshaft position sensor
• Engine head temperature sensor
• Oxygen sensor
• Oil pressure switch
• CO monitor
• Current transducer
See Figure 2-10. The ECM is located on the right side of
the generator frame when looking at the unit from the
front. A large single connector connects the ECM to the
generator main control panel and to the engine harness.
Diagnostic Repair Manual
Figure 2-10. ECM Location
Wiring Harness
The wiring harness connects the ECM directly to the
control panel and to the various engine sensors and
controllers.
Main Power Relay
See Figure 2-11. The main power relay (MPR), located
inside the control panel, supplies 12 VDC to:
• Key start switch
014990
• Field boost relay
• Fuel pump
• Starter contactor
• Malfunction indicator lamp
Figure 2-11. Main Power Relay
Starter Relay
See Figure 2-12. The starter relay (STR) is located
inside the control panel. The STR receives a signal from
the ECM to activate the starter motor.
608
14B
87
15
86
15
87a
85
30
56
16
87 14C
86
14C
87a
85
30
Figure 2-12. Starter Relay
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014992
014993
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