[Diy_efi] Key-On Power for 7730

[Van Setten, Tim @ ACSSD]

Use the diodes on the control coil side of a relay.  This way, the
switched part of the relay is supplying 100% power from the battery to
the ECM (no voltage drops).  The mechanical delay of the relay should be
fine between the two sources on the control side.  One could always put
a cap on the control side of the relay to increase this "Hold"
time......Tim.