The Electronic Control Module (ECM) contains the logic and the outputs for control of starting and of shutdown. The ECM responds to signals from the following components: engine control, emergency stop switch, remote start, data link, and driven equipment.
The following Steps describe the electronic control system start/stop sequencing:
- The ECM receives one of the following signals for start-up:
- The engine control is set to the "START" mode.
- The engine control is in the "AUTO" mode and the remote start/stop initiate contact closes.
- After receiving a signal for start-up, the ECM waits for the programmable "Driven Equipment Delay Time" prior to cranking.
The ECM will not start the engine until the input for driven equipment is grounded.
If the driven equipment input circuit is opened during engine operation, the engine will shut down.
- After input for the driven equipment is grounded, the ECM supplies +Battery voltage to the solenoid for the starting motor. The starting motor cranks the engine without fuel and without ignition until the "Engine Purge Cycle Time" has elapsed.
The "Engine Purge Cycle Time" allows any unburned fuel to exit through the exhaust system prior to ignition. The cycle helps prevent combustion in the exhaust system.
Note: The "Engine Purge Cycle Time" must be activated with a factory password by the customer. The parameter can be turned off and on, and the time interval can be adjusted.
- After the "Engine Purge Cycle Time" has elapsed, the ECM verifies that the engine rpm is greater than 100.
The engine has an energize-to-run type of GSOV. This means that the GSOV must be energized in order to open. When the GSOV is open, fuel is allowed to flow to the engine.
If the engine rpm is greater than 100, the Gas Shutoff Valve (GSOV) is energized. The GSOV may be energized by the ECM, or by the customer equipment. The ECM energizes the ignition transformers. The ECM sends a fuel command to the fuel metering valve in order to supply sufficient fuel for a combustible air/fuel mixture. The ECM also sends a throttle command to the throttle actuator.
If the engine rpm is not greater than 100, the GSOV will not be energized. The engine cannot start.
- After the engine starts and the programmable crank terminate speed is achieved, the ECM removes the voltage from the starting motor solenoid. The pinion of the starting motor disengages from the flywheel ring gear.
- The engine runs until the ECM receives a shutdown signal.
The following conditions cause a shutdown signal:
- The remote start/stop initiate contact opens when the engine control switch is in the "AUTO" position.
- The engine control is in the "COOLDOWN /STOP" mode.
- The "EMERGENCY STOP" button is pressed.
- The ECM senses an undesirable operating condition and an engine shutdown is initiated.
The engine control "OFF/RESET" is not recommended for normal shutdown. The "EMERGENCY STOP" is not recommended for normal shutdown. Only the "EMERGENCY STOP" and an overspeed condition will cause both the fuel and the ignition to be stopped immediately. The cool down cycle will not operate.
Any shutdown that is initiated by the ECM is the result of a condition that is undesirable and/or unplanned.
One of the following conditions initiates a normal shutdown:
- The engine control switch is turned to the "COOLDOWN/STOP" position.
- The engine control switch is in the "AUTO" position and the remote start/stop initiate contact opens.
- The engine operates for the programmable cool down period before the engine stops. After the cool down period, the ECM removes the +Battery voltage from the solenoid for the GSOV and the fuel flow is stopped.
- The ignition continues to operate without a fuel supply until the engine speed is less than 40 rpm. Then, the ECM terminates the ignition. The engine coasts to a stop.
If the engine speed is not reduced below 100 rpm during the programmable "Engine Speed Drop Time", the ECM terminates the ignition. The ECM activates an emergency stop.