How to install electronic ignition?

[Skunkworks Challenger]

I'm installing a Mopar performance electronic ignition in my 70 Challenger RT with a 440.  I'm a little confused by the instructions which say:  Find the hot wire (feed) from the ignition switch at the ballast resistor.  Splice on the light blue wire (with yellow tracer) that goes from the ECU  to the feed wire.  This means that line voltage(12 volts) is by-passing the ballast resistor and going directly to the ECU.  It also means that the wire on the output side of the ballast resistor is going to the positive pole on the coil.  The negative pole on the coil is fed from the ECU.  So, at start up the coil is getting full 12 volts then reverts to reduced voltage to run but the ECU is still getting full 12 volts anytime the key is on.  Is this a correct assumption?  I didn't expect that the ECU would get full voltage except at start-up.  PK

[Topcat]

Here's a drawing.

[Skunkworks Challenger]

Topcat, you are the man!  Pretty clear diagram.  Looks like the light blue wire with tracer just powers up the ECU while the coil is powered up the conventional way.  Thanks much!  PK

[Chryco Psycho]

the ECU is always 12v powered , only the coil drops voltage

[Skunkworks Challenger]

Mike and Neil, thanks for the help.  I have the unit installed and tested.  I didn't start the engine but put a timing light on # one plug wire and applied vacuum to the vacuum advance which gives me spark as the pick-up rotates back and forth past the reluctor. I've attached photos that show the installation.  Since my car is a 70 model and didn't originally have electronic ignition  I opted to install the ECU in an alternate location. I used my existing feed wire and start-up circuit to the coil and joined a new wire at the ballast resistor to the main ignition feed to supply the constant 12 volts to the ECU.  The supplied light blue wire with yellow tracer was not long enough due to my mounting location.  I shortened the two wires to the distributor and the black W/tracer to the coil negative post to fit the circumstances. Note the one picture in the instruction sheet showing the rotation direction of the big block distributor. The verbiage says it rotates counter clockwise which is correct and the way I set it up. PK

[Topcat]

Glad to hear it's coming along. I did look at your pictures. Nice work so far.

For pictures, I use Imageshack.

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