So here's an 'interesting thing'! Have replaced my ignition switch see
here but today I notice that when I hit the start position 3 - bang, flashing IC lamps again!!!
OK, this time it must be the battery causing excessive voltage drop as the starter begins to turn. The initial current from starters under locked start condition is HUGE and so the voltage dips significantly. If your battery's a little tired then this drop is very significant and subsequently shutdown of all electronic modules is inevitable - the IC lamps extinguish.
When the volts fall below the operating point of the solenoid the starter stops pulling current and the volts begin to rise again, momentarily causing the IC to illuminate. Subsequently the solenoid clicks back in causing the starter to pull huge current again - then the whole oscillation process begins.
Today I find my bat is 9V just in position 2 with the IC on!!!
Here's some short video of the oscillation you may experience when you have battery issues or of course when the ignition switch fails and causes a similar poor connection.
Oscillation Video