Service manual

90-898303

4-13

Electronic Control Module (ECM)

The ECM is continually monitoring various engine conditions (engine

temperature, engine detonation control , engine throttle opening and climate

conditions (induction air temperature, barometric pressure and altitude level)

needed to calculate fuel delivery (pulse width length) of injectors. The pulse

width is constantly adjusted (rich/lean conditions) to compensate for operating

conditions, such as cranking, cold starting, climate conditions, altitude,

acceleration and deceleration, allowing the outboard to operate efficiently at

all engine speeds.

12 Volt Battery - The 12 volt battery provides power to the ECM through the

main power relay.

IMPORTANT: When disassembling EFI System DISCONNECT BATTERY

CABLES.

The ECM requires 8 VDC minimum to operate. If the ECM should fail, the

engine will stop running.

The inputs to the ECM can be monitored and tested by the Digital Diagnostic

Terminal 91-823686A2 using adaptor harness 84-822560A5.

The ECM performs the following functions:

• Calculates the precise fuel and ignition timing requirements based on

engine speed, throttle position, manifold pressure and coolant

temperature.

• Controls fuel injectors for each cylinder and ignition for each cylinder.

• Controls all alarm horn functions.

• Supplies tachometer signal to gauge.

• Controls RPM limit function.

• Contains detonation control circuitry.

• Records engine running information.

c) Electronic Control Module (ECM)

Notes

_______________________