87121-ZW0-000 Honda MARK, RR. (BF75) (Honda Code 4900486).

Electronic Controls
Electronic Control Module
The ECM consists of two main components, the control computer (hardware) and the flash file (software). The control computer consists of a microprocessor and electronic circuitry. The flash file contains the engine operational characteristics. The operating maps influence the engine performance.Engine Governor
The engine ECM governs engine speed. The engine ECM and the flash file work together by controlling the amount of fuel that is delivered by the injectors. Desired engine rpm is determined by the throttle position sensor signal and certain sensor readings. Diagnostic codes may derate the engine. Actual engine rpm is measured by the engine speed/timing signal.Fuel Injection
The engine ECM controls the timing and the duration of the fuel that is injected. The engine ECM varies the signals to the fuel injectors. Fuel is injected only while an injector solenoid is energized by a 105 V signal from the engine ECM. The timing of the injection signal determines the engine timing. The length of the injection signal determines engine speed. By controlling the timing and duration of the 105 V signal, the ECM controls the engine speed.Injection timing depends on the following conditions: desired engine rpm and load. The ECM detects the top center of each cylinder. The ECM sends an injection signal at the desired time.Cold Mode Operation
The engine ECM uses cold mode operation in order to reduce white smoke during engine warm-up. The engine ECM cuts out the injectors one at a time in order to determine if the cylinder is firing. If the cylinder is firing correctly, the engine ECM leaves the injector on. If the cylinder is not firing, the engine ECM will leave the injector turned off. This action will increase startability and this action will reduce warm-up time.Cold mode is activated whenever the engine coolant temperature falls below a predetermined value. Cold mode remains active until the engine has warmed or a time limit is exceeded.FRC Limit
The flash file inside the engine ECM sets certain limits on the amount of fuel that can be injected. The FRC limit is a limit that is based on the boost pressure. The boost pressure is calculated as the difference in pressure between atmospheric pressure and turbocharger outlet pressure. The FRC limit is used to control the air/fuel ratio for control of emissions. When the engine ECM senses a higher boost pressure, the engine ECM increases the FRC limit. A higher boost pressure indicates that there is more air in the cylinder. When the engine ECM increases the FRC limit, the engine ECM allows more fuel into the cylinder.Rated Fuel Position
The rated fuel position is a limit that is based on the power rating of the engine. The rated fuel position is similar to the rack stops and the torque spring on a mechanically governed engine. The rated fuel position determines maximum power and torque values for a specific engine family and a specific rating. The rated fuel position is programmed into the flash file at the factory.Electronic Governor
Illustration 1 g01214361Engine Wiring Diagram
Illustration 2 g03322163Location of the Engine Sensors
Illustration 3 g01217417
Left side view
(1) Coolant temperature sensor
(2) Electronic monitoring system
(3) Left air shutoff
(4) Left exhaust temperature sensor
(5) "Connector "A""
(6) "Connector "B""
(7) Service tool connector
(8) Customer connector (40 pin)
(9) Customer connector (24 pin)
(10) Crankcase pressure sensor
(11) Ether starting aid
(12) Starting motors
(13) Engine speed/timing sensor
Illustration 4 g01217418
Right side view
(14) Right exhaust temperature sensor
(15) Right air shutoff
(16) Filtered engine oil pressure sensor
(17) Filtered fuel pressure sensor
(18) Unfiltered fuel pressure sensor
(19) Air start solenoid
(20) Prelube pump motor
Illustration 5 g01217419
Front and rear view
(21) Unfiltered engine oil pressure sensor
(22) Turbocharger compressor outlet pressure sensor
(23) Atmospheric pressure sensor
(24) Left turbocharger inlet pressure sensor
(25) Right turbocharger inlet pressure sensor
(26) J1/P1 ECM connector
(27) ECM
(28) J2/P2 ECM connector Engine Starting and Stopping Procedures
Engine Starting Sequence
The generator control module will receive one of the following start signals:
The operator places the control in the RUN mode.
The operator places the control in the AUTO mode and the remote initiate input becomes active.
The operator places the control in the AUTO mode and a start command is sent via Data Link.
The generator control module performs the following system checks:
No system faults are present
All previous shutdown faults have been reset
The engine is not already running
If the prelube is not complete, the generator control module will not crank the engine.
The generator control module begins the following cranking sequence:
Activate the Starting Motor Relay (SMR)
A start signal is sent to the engine ECM via the Cat Data Link and the fuel control relay is activated.
The generator control enables cranking the engine until the cycle crank time reaches the setpoint for total crank time or until the engine starts.
The generator control module deactivates the SMR when the engine speed reaches the setpoint for crank terminate speed. Engine Stopping Procedure
The generator control module receives one of the following engine stop signals:
The operator places the control in the STOP mode.
The operator places the control in the AUTO mode and the remote initiate input becomes inactive.
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