Cartwaveforms > ignition > eco tec ecm to amplifier signals > Vauxhall ECOTEC ECM to Coil
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Vauxhall ECOTEC ECM to Coil Waveform Notes
The double ended coil in this particular case, differs from many other systems as it has the ignition amplifier built into the coil pack. The coil/amplifier pack will have 4 electrical connections. The pack receives a 12 volt supply from the ignition switch, has an independent earth return and the remaining two connections are in the form of a 5 volt 'squarewave' digital signal from the Electronic Control Module (ECM). The ECM will receive information from the engines sensors and calculates the point of ignition by the ECM from its internal pre-set parameter. At the designated point, the 5 volt supply drops to zero volts, signaling the amplifier to remove the earth path on the coil primary, firing the coil.
The coil/amplifier pack has two separate sides (one for cylinders 1 + 4 and the other for cylinders 2 + 3). Using an oscilloscope with dual trace both circuits can be monitored and it can be seen that the coils are fired alternately, as the example shows.
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