I have been testing my wiring harness from the EC2.  I found a behavior that I did not expect.  The manual drawing (EC2 manual) show a single injector supply that splits at the Injector primary and secondary disable switches.  On my installation, I have 2 separate feeder circuits, supply Primary comes from battery 1, and supply Secondary comes from battery 2.  I did this for redundancy.  If I had a failure such as a short to ground in either circuit, its related overload should trip, but the other circuit should remain active. 

While testing the injector circuits, I noticed what I would term an abnormality.  With both injector disable switches in the enable position, I turned on the power for the primary circuit (I have LED indicators on all circuits that annunciate power present) and the secondary circuit also showed power present even though the power switch for the secondary circuit was off.  The same is true when the secondary circuit is engaged and the primary is off. 

Initially this led me to think I had miss wired something in the circuit.  After checking out the wiring, I found no issues.  So I took a closer look at the wiring diagram in the manual.  It turns out the power was being back feed through the injectors to the opposite circuit.  On the 20B version of the EC2, the injector control lines for each rotors injectors are junctioned going into the EC2.  For example the Rotor 1 Primary and Secondary control lines are junctioned into a single input point at the EC2. 

I can see several situations where this may lead to undesirable operation.  For example, if the Primary circuit had a hard short to ground, it would take out the primary circuit's overload (CB or Fuse.)  Since the primary and secondary circuits are electrically connected on the control line, the other circuit would also trip.  Another situation that could occur is a medium to high resistance short.  Current would then flow uncontrolled through the unaffected circuit's injector to the affected circuit's injector then to the resistance short.  This could keep both injectors on 100%.  While this situation is unlikely, it seems possible.

I believe the 13B version uses separate control lines for each injector, so this in not likely to be an issue on the 13B version.

It appears that isolation diodes are needed to prevent these possible problems.  Before making any changes I have to look the circuit over more closely, as well as a call to Tracy on the next service day.  My question to the group, especially anyone with a 20B, is am I looking at this wrong?

Thanks,

Joe