MEFI Fuel Injection
Ignition Control Module - Cranking
The picture above describes IC operation during cranking. To help understand how the circuit operates, a relay with a double set of of contacts is shown inside the IC module. Actually solid state circuitry is used, but for illustration purposes a relay makes it easier to visualize and explain. Module Mode (cranking mode) During cranking, the relay is de-energized, allowing a set of contacts to connect the pick-up coil to the base of the transistor. When the pick-up coil applies a positive voltage the transistor turns “on”, when voltage is removed the transistor turns “off”. When it is off the primary current stops and a spark is developed. Cranking is defined as RPM below 400, at this time the ECM has grounded the IC line at terminal “E” and has no voltage applied to the by-pass line at terminal “B”. At this point the IC module has ignition control. A small amount of advance is built into the IC module, in case the engine remains or defaults to module mode.
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