20581875 Volvo.Penta Pipe

Illustration 1 g06594056ECM (6) is mounted on the engine. The ECM must be programmed for the installation to control the ignition. Cat ET (7) is used to program the ECM. Either electronic service tool can be connected to remote control panel (1) or junction box (2).Note: For information on the programmable parameters, refer to Systems Operation, "Electronic Control System Parameters". For information on the monitoring system, refer to Systems Operation, "Engine Monitoring System".Two switches affect the ignition system: the engine control switch (ECS) and the switch for fuel selection.When the ECS on remote control panel (1) is switched to MANUAL START, the ECM operates the ignition system.If the switch for fuel selection is in the NATURAL GAS position, the ECM control module will use the desired timing that is programmed. If the switch for fuel selection is in the PROPANE position, the ECM retards the timing by 6 degrees.The ECM uses engine speed/timing sensor (3), manifold air pressure sensor (4), and detonation sensors (5) to monitor engine operation. The ECM determines the ignition timing. The module initiates the timing via ignition transformer (9) and spark plug (10).Information from the ECM is sent to engine-mounted junction box (2) and the remote control panel. If a problem with the electronic system is detected, a diagnostic code is generated. The diagnostic code can be monitored with the remote control panel or with an electronic service tool.Note: If the engine has air/fuel ratio control, the control module communicates with the ECM via the Cat Data Link.The ECM has several internal components that perform different functions. The components and the functions are listed in Table 1.
Table 1
Internal Components and Functions of the Control Module
Component Function
Ignition control Receive input from the engine control switch, the switch for fuel selection, and the DDT.
Provide information on engine status and diagnostics to electronic service tools.
Provide desired timing and voltage to the ignition transformer control.
Receive input from the interpreters and the filter.
Ignition transformer control Receive input from the ignition control.
Provide voltage to the transformers.
Provide input to the interpreter of diagnostics for the transformers.
Interpreter of diagnostics for the transformers Receive input from the ignition transformers control.
Provide input to the ignition control.
Interpreter for the signal from the engine speed/timing sensor Receive input from the engine speed/timing sensor.
Provide input to the ignition control.
Interpreter for the signal from the manifold air pressure sensor Receive input from the manifold air pressure sensor.
Provide input to the ignition control.
Filter for the detonation sensors Receive input from the detonation sensors.
Provide input to the ignition control. The relationships of the ECM, the sensors, and the transformers are described below.Distribution Panel
Illustration 2 g06597855An optional distribution panel (1) may be attached to ECM (3). Conduit (2) is used from the distribution panel to the engine block for the primary circuit for the transformers. The distribution panel is used for engines that are configured for Canadian Standards Association (CSA) requirements.Engine Speed/Timing Sensor
The engine speed/timing sensor provides information about engine speed and the position of the crankshaft to the ECM.
Illustration 3 g06597856
(1) Engine speed/timing sensorA timing wheel is mounted on the rear of the left camshaft. Engine speed/timing sensor (1) is installed in the cover. The sensor is a magnetic pickup. The ECM supplies approximately 13 VDC to the sensor. As the teeth of the timing wheel rotate past the sensor, the sensor generates a signal that matches the pattern of the teeth. The signal is sent to an interpreter for the ECM.
Illustration 4 g02721036
Engine speed/timing sensor and timing wheel
The timing wheel has a special tooth pattern that indicates the position of the camshaft and the direction of rotation. The timing wheel has 24 slots in the outer diameter. Twenty-one of the slots are narrow. Three of the slots are about 2.5 times wider than the rest of the slots. When the engine rotates in the normal direction, the slots pass the engine speed/timing sensor in the following order:
one wide slot
three narrow slots
two wide slots
18 narrow slotsThe number one cylinder is at the top center position when the edge of the third narrow slot passes the center of the sensor. All 24 teeth pass the sensor during one revolution of the camshaft or two revolutions of the crankshaft.With information from the engine speed/timing sensor, the ECM is able to calculate the positions of the pistons in the cylinders. According to the ignition timing that is selected, the ECM sends voltage pulses to the transformers for firing of the spark plugs.The engine speed/timing sensor also monitors engine speed. If a speed sensitive timing map is selected, the ECM adjusts the ignition timing according to the engine rpm.The ECM will shut down the engine if problems with the engine speed/timing sensor electrical circuit are detected. The corresponding diagnostic code is generated.Manifold Air Pressure Sensor
Illustration 5 g00309908
Previous design of the manifold air pressure sensor